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• YouTube Scalability Lessons

  - by Bertrand Matthelié

  @font-face { font-family: "Arial"; }@font-face { font-family: "Courier New"; }@font-face { font-family: "Wingdings"; }@font-face { font-family: "Calibri"; }@font-face { font-family: "Cambria"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: "Times New Roman"; }h2 { margin: 12pt 0cm 3pt; page-break-after: avoid; font-size: 14pt; font-family: "Times New Roman"; font-style: italic; }a:link, span.MsoHyperlink { color: blue; text-decoration: underline; }a:visited, span.MsoHyperlinkFollowed { color: purple; text-decoration: underline; }span.Heading2Char { font-family: Calibri; font-weight: bold; font-style: italic; }div.Section1 { page: Section1; }ol { margin-bottom: 0cm; }ul { margin-bottom: 0cm; } Very interesting blog post by Todd Hoff at highscalability.com presenting “7 Years of YouTube Scalability Lessons in 30 min” based on a presentation from Mike Solomon, one of the original engineers at YouTube: …. The key takeaway away of the talk for me was doing a lot with really simple tools. While many teams are moving on to more complex ecosystems, YouTube really does keep it simple. They program primarily in Python, use MySQL as their database, they’ve stuck with Apache, and even new features for such a massive site start as a very simple Python program. That doesn’t mean YouTube doesn’t do cool stuff, they do, but what makes everything work together is more a philosophy or a way of doing things than technological hocus pocus. What made YouTube into one of the world’s largest websites? Read on and see... Stats @font-face { font-family: "Arial"; }@font-face { font-family: "Cambria"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: "Times New Roman"; }div.Section1 { page: Section1; } 4 billion Views a day 60 hours of video is uploaded every minute 350+ million devices are YouTube enabled Revenue double in 2010 The number of videos has gone up 9 orders of magnitude and the number of developers has only gone up two orders of magnitude. 1 million lines of Python code Stack @font-face { font-family: "Arial"; }@font-face { font-family: "Cambria"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: "Times New Roman"; }div.Section1 { page: Section1; } Python - most of the lines of code for YouTube are still in Python. Everytime you watch a YouTube video you are executing a bunch of Python code. Apache - when you think you need to get rid of it, you don’t. Apache is a real rockstar technology at YouTube because they keep it simple. Every request goes through Apache. Linux - the benefit of Linux is there’s always a way to get in and see how your system is behaving. No matter how bad your app is behaving, you can take a look at it with Linux tools like strace and tcpdump. MySQL - is used a lot. When you watch a video you are getting data from MySQL. Sometime it’s used a relational database or a blob store. It’s about tuning and making choices about how you organize your data. Vitess- a  new project released by YouTube, written in Go, it’s a frontend to MySQL. It does a lot of optimization on the fly, it rewrites queries and acts as a proxy. Currently it serves every YouTube database request. It’s RPC based. Zookeeper - a distributed lock server. It’s used for configuration. Really interesting piece of technology. Hard to use correctly so read the manual Wiseguy - a CGI servlet container. Spitfire - a templating system. It has an abstract syntax tree that let’s them do transformations to make things go faster. Serialization formats - no matter which one you use, they are all expensive. Measure. Don’t use pickle. Not a good choice. Found protocol buffers slow. They wrote their own BSON implementation, which is 10-15 time faster than the one you can download. ...Contiues. Read the blog Watch the video

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• Breaking 1NF to model subset constraints. Does this sound sane?

  - by Chris Travers

  My first question here. Appologize if it is in the wrong forum but this seems pretty conceptual. I am looking at doing something that goes against conventional wisdom and want to get some feedback as to whether this is totally insane or will result in problems, so critique away! I am on PostgreSQL 9.1 but may be moving to 9.2 for this part of this project. To re-iterate: Does it seem sane to break 1NF in this way? I am not looking for debugging code so much as where people see problems that this might lead. The Problem In double entry accounting, financial transactions are journal entries with an arbitrary number of lines. Each line has either a left value (debit) or a right value (credit) which can be modelled as a single value with negatives as debits and positives as credits or vice versa. The sum of all debits and credits must equal zero (so if we go with a single amount field, sum(amount) must equal zero for each financial journal entry). SQL-based databases, pretty much required for this sort of work, have no way to express this sort of constraint natively and so any approach to enforcing it in the database seems rather complex. The Write Model The journal entries are append only. There is a possibility we will add a delete model but it will be subject to a different set of restrictions and so is not applicable here. If and when we allow deletes, we will probably do them using a simple ON DELETE CASCADE designation on the foreign key, and require that deletes go through a dedicated stored procedure which can enforce the other constraints. So inserts and selects have to be accommodated but updates and deletes do not for this task. My Proposed Solution My proposed solution is to break first normal form and model constraints on arrays of tuples, with a trigger that breaks the rows out into another table. CREATE TABLE journal_line ( entry_id bigserial primary key, account_id int not null references account(id), journal_entry_id bigint not null, -- adding references later amount numeric not null ); I would then add "table methods" to extract debits and credits for reporting purposes: CREATE OR REPLACE FUNCTION debits(journal_line) RETURNS numeric LANGUAGE sql IMMUTABLE AS $$ SELECT CASE WHEN $1.amount < 0 THEN $1.amount * -1 ELSE NULL END; $$; CREATE OR REPLACE FUNCTION credits(journal_line) RETURNS numeric LANGUAGE sql IMMUTABLE AS $$ SELECT CASE WHEN $1.amount > 0 THEN $1.amount ELSE NULL END; $$; Then the journal entry table (simplified for this example): CREATE TABLE journal_entry ( entry_id bigserial primary key, -- no natural keys :-( journal_id int not null references journal(id), date_posted date not null, reference text not null, description text not null, journal_lines journal_line[] not null ); Then a table method and and check constraints: CREATE OR REPLACE FUNCTION running_total(journal_entry) returns numeric language sql immutable as $$ SELECT sum(amount) FROM unnest($1.journal_lines); $$; ALTER TABLE journal_entry ADD CONSTRAINT CHECK (((journal_entry.running_total) = 0)); ALTER TABLE journal_line ADD FOREIGN KEY journal_entry_id REFERENCES journal_entry(entry_id); And finally we'd have a breakout trigger: CREATE OR REPLACE FUNCTION je_breakout() RETURNS TRIGGER LANGUAGE PLPGSQL AS $$ BEGIN IF TG_OP = 'INSERT' THEN INSERT INTO journal_line (journal_entry_id, account_id, amount) SELECT NEW.id, account_id, amount FROM unnest(NEW.journal_lines); RETURN NEW; ELSE RAISE EXCEPTION 'Operation Not Allowed'; END IF; END; $$; And finally CREATE TRIGGER AFTER INSERT OR UPDATE OR DELETE ON journal_entry FOR EACH ROW EXECUTE_PROCEDURE je_breaout(); Of course the example above is simplified. There will be a status table that will track approval status allowing for separation of duties, etc. However the goal here is to prevent unbalanced transactions. Any feedback? Does this sound entirely insane? Standard Solutions? In getting to this point I have to say I have looked at four different current ERP solutions to this problems: Represent every line item as a debit and a credit against different accounts. Use of foreign keys against the line item table to enforce an eventual running total of 0 Use of constraint triggers in PostgreSQL Forcing all validation here solely through the app logic. My concerns are that #1 is pretty limiting and very hard to audit internally. It's not programmer transparent and so it strikes me as being difficult to work with in the future. The second strikes me as being very complex and required a series of contraints and foreign keys against self to make work, and therefore it strikes me as complex, hard to sort out at least in my mind, and thus hard to work with. The fourth could be done as we force all access through stored procedures anyway and this is the most common solution (have the app total things up and throw an error otherwise). However, I think proof that a constraint is followed is superior to test cases, and so the question becomes whether this in fact generates insert anomilies rather than solving them. If this is a solved problem it isn't the case that everyone agrees on the solution....

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• #OOW 2012 : IaaS, Private Cloud, Multitenant Database, and X3H2M2

  - by Eric Bezille

  The title of this post is a summary of the 4 announcements made by Larry Ellison today, during the opening session of Oracle Open World 2012... To know what's behind X3H2M2, you will have to wait a little, as I will go in order, beginning with the IaaS - Infrastructure as a Service - announcement. Oracle IaaS goes Public... and Private... Starting in 2004 with Fusion development, Oracle Cloud was launch last year to provide not only SaaS Application, based on standard development, but also the underlying PaaS, required to build the specifics, and required interconnections between applications, in and outside of the Cloud. Still, to cover the end-to-end Cloud  Services spectrum, we had to provide an Infrastructure as a Service, leveraging our Servers, Storage, OS, and Virtualization Technologies, all "Engineered Together". This Cloud Infrastructure, was already available for our customers to build rapidly their own Private Cloud either on SPARC/Solaris or x86/Linux... The second announcement made today bring that proposition a big step further : for cautious customers (like Banks, or sensible industries) who would like to benefits from the Cloud value of "as a Service", but don't want their Data out in the Cloud... We propose to them to operate the same systems, Exadata, Exalogic & SuperCluster, that are providing our Public Cloud Infrastructure, behind their firewall, in a Private Cloud model. Oracle 12c Multitenant Database This is also a major announcement made today, on what's coming with Oracle Database 12c : the ability to consolidate multiple databases with no extra additional  cost especially in terms of memory needed on the server node, which is often THE consolidation limiting factor. The principle could be compare to Solaris Zones, where, you will have a Database Container, who is "owning" the memory and Database background processes, and "Pluggable" Database in this Database Container. This particular feature is a strong compelling event to evaluate rapidly Oracle Database 12c once it will be available, as this is major step forward into true Database consolidation with Multitenancy on a shared (optimized) infrastructure. X3H2M2, enabling the new Exadata X3 in-Memory Database Here we are :  X3H2M2 stands for X3 (the new version of Exadata announced also today) Heuristic Hierarchical Mass Memory, providing the capability to keep most if not all the Data in the memory cache hierarchy. Of course, this is the major software enhancement of the new X3 Exadata machine, but as this is a software, our current customers would be able to benefit from it on their existing systems by upgrading to the new release. But that' not the only thing that we did with X3, at the same time we have upgraded everything : the CPUs, adding more cores per server node (16 vs. 12, with the arrival of Intel E5 / Sandy Bridge), the memory with 512GB memory as well per node,  and the new Flash Fire card, bringing now up to 22 TB of Flash cache. All of this 4TB of RAM + 22TB of Flash being use cleverly not only for read but also for write by the X3H2M2 algorithm... making a very big difference compare to traditional storage flash extension. But what does those extra performances brings to you on an already very efficient system: double your performances compare to the fastest storage array on the market today (including flash) and divide you storage price x10 at the same time... Something to consider closely this days... Especially that we also announced the availability of a new Exadata X3-2 8th rack : a good starting point. As you have seen a major opening for this year again with true innovation. But that was not the only thing that we saw today, as before Larry's talk, Fujitsu did introduce more in deep the up coming new SPARC processor, that they are co-developing with us. And as such Andrew Mendelsohn - Senior Vice President Database Server Technologies came on stage to explain that the next step after I/O optimization for Database with Exadata, was to accelerate the Database at execution level by bringing functions in the SPARC processor silicium. All in all, to process more and more Data... The big theme of the day... and of the Oracle User Groups Conferences that were also happening today and where I had the opportunity to attend some interesting sessions on practical use cases of Big Data one in Finances and Fraud profiling and the other one on practical deployment of Oracle Exalytics for Data Analytics. In conclusion, one picture to try to size Oracle Open World ... and you can understand why, with such a rich content... and this only the first day !

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• Is your dream an international experience?

  - by Maria Sandu

  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-family:"Calibri","sans-serif"; mso-ascii- mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi- mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Studying in Poland, having two summer jobs in England, doing one internship in India, working in Thailand for half a year and now working in Prague. Does it seem an adventure? Well it is and I will tell you how I came to have this international experience. Dzien Dobry! My name is Wojciech Jurojc, I am Polish and I am currently a Business Development Consultant within Oracle, based in Prague. I joined Oracle on the 1st of August 2011. I graduated in 2010 and obtained 2 Masters Degrees in Political Science and Economics. I would like to tell you more about my past and how I joined Oracle. In 2005 I began studying at the Faculty of Political Sciences Gdansk University. In 2008, I obtained a Bachelors Degree. During these three years I had the opportunity to go to England twice, where I worked as a Bartender, first in Blackpool and then in Manchester. This allowed me to improve my language skills and become more confident. In the meantime, I joined the International Student Organization-AIESEC, where I was organized conferences and conducted student projects. Also I met a mass of interesting people from around the world. After graduation in 2008, I was able to get an Internship within a big company in Poland. I worked there as an Intern in the Purchase Department. That was my first adventure within a corporate environment. I learnt a lot about purchasing processes and negotiations. In September 2008, I started studying two Masters Faculties: Political Science and Economics. It was very difficult, but it was not impossible. Over the next two years of studying I was able to go on a three month internship to India where I worked as a Marketing Assistant in an NGO. I was travelling around northern India and did presentations to the academic community about green energy and environmental projects. I had the opportunity to visit Nepal and walked in the Himalayas. That was a huge experience as well as a cultural shock. It taught me how to deal with many problems and to appreciate what I have. At the end of 2009 I was working as a Marketing Assistant for a Leasing company, where I learnt useful sales knowledge and improved my objection handling skills. In July 2010, I graduated with a double Masters and found a job in Thailand as Sales Representative in an IT company. I worked in Thailand until the end of January 2011. Besides that, I was working in an International company with interesting people and I had the opportunity to travel around Thailand and visit Cambodia. After this adventure I started looking for jobs in Europe where I could further develop my sales skills. I found Oracle and I don’t regret this decision which I made. I am currently working in Prague in an international Hardware team and I know that is not the end of my adventures. At this moment, I am working in a team of 12 members. Ten of them are based in Prague and 2 others are based in Russia. We come from different countries such as: Czech Republic, Russia, Ukraine, Turkey, Slovakia and Kazakhstan. I am working on the Polish market, cooperating with our Hardware customers and partners. What do I enjoy the most about my job? I enjoy every challenge that I face in my daily activities as there are always new experiences for me and new things that I learn. As part of Oracle, I gain international exposure and therefore more career opportunities to explore. I have planned my next step for the career path I dream of and I am currently working on it. I recommend you check our Career Page if you’re looking for an international career. If you want to find out more about our job opportunities, follow us on https://campus.oracle.com .

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• Understanding the 'High Performance' meaning in Extreme Transaction Processing

  - by kyap

  Despite my previous blogs entries on SOA/BPM and Identity Management, the domain where I'm the most passionated is definitely the Extreme Transaction Processing, commonly called XTP.I came across XTP back to 2007 while I was still FMW Product Manager in EMEA. At that time Oracle acquired a company called Tangosol, which owned an unique product called Coherence that we renamed to Oracle Coherence. Beside this innovative renaming of the product, to be honest, I didn't know much about it, except being a "distributed in-memory cache for Extreme Transaction Processing"... not very helpful still.In general when people doesn't fully understand a technology or a concept, they tend to find some shortcuts, either correct or not, to justify their lack-of understanding... and of course I was part of this category of individuals. And the shortcut was "Oracle Coherence Cache helps to improve Performance". Excellent marketing slogan... but not very meaningful still. By chance I was able to get away quickly from that group in July 2007* at Thames Valley Park (UK), after I attended one of the most interesting workshops, in my 10 years career in Oracle, delivered by Brian Oliver. The biggest mistake I made was to assume that performance improvement with Coherence was related to the response time. Which can be considered as legitimus at that time, because after-all caches help to reduce latency on cached data access, hence reduce the response-time. But like all caches, you need to define caching and expiration policies, thinking about the cache-missed strategy, and most of the time you have to re-write partially your application in order to work with the cache. At a result, the expected benefit vanishes... so, not very useful then?The key mistake I made was my perception or obsession on how performance improvement should be driven, but I strongly believe this is still a common problem to most of the developers. In fact we all know the that the performance of a system is generally presented by the Capacity (or Throughput), with the 2 important dimensions Speed (response-time) and Volume (load) :Capacity (TPS) = Volume (T) / Speed (S)To increase the Capacity, we can either reduce the Speed(in terms of response-time), or to increase the Volume. However we tend to only focus on reducing the Speed dimension, perhaps it is more concrete and tangible to measure, and nicer to present to our management because there's a direct impact onto the end-users experience. On the other hand, we assume the Volume can be addressed by the underlying hardware or software stack, so if we need more capacity (scale out), we just add more hardware or software. Unfortunately, the reality proves that IT is never as ideal as we assume...The challenge with Speed improvement approach is that it is generally difficult and costly to make things already fast... faster. And by adding Coherence will not necessarily help either. Even though we manage to do so, the Capacity can not increase forever because... the Speed can be influenced by the Volume. For all system, we always have a performance illustration as follow: In all traditional system, the increase of Volume (Transaction) will also increase the Speed (Response-Time) as some point. The reason is simple: most of the time the Application logics were not designed to scale. As an example, if you have a while-loop in your application, it is natural to conceive that parsing 200 entries will require double execution-time compared to 100 entries. If you need to "Speed-up" the execution, you can only upgrade your hardware (scale-up) with faster CPU and/or network to reduce network latency. It is technically limited and economically inefficient. And this is exactly where XTP and Coherence kick in. The primary objective of XTP is about designing applications which can scale-out for increasing the Volume, by applying coding techniques to keep the execution-time as constant as possible, independently of the number of runtime data being manipulated. It is actually not just about having an application running as fast as possible, but about having a much more predictable system, with constant response-time and linearly scale, so we can easily increase throughput by adding more hardwares in parallel. It is in general combined with the Low Latency Programming model, where we tried to optimize the network usage as much as possible, either from the programmatic angle (less network-hoops to complete a task), and/or from a hardware angle (faster network equipments). In this picture, Oracle Coherence can be considered as software-level XTP enabler, via the Distributed-Cache because it can guarantee: - Constant Data Objects access time, independently from the number of Objects and the Coherence Cluster size - Data Objects Distribution by Affinity for in-memory data grouping - In-place Data Processing for parallel executionTo summarize, Oracle Coherence is indeed useful to improve your application performance, just not in the way we commonly think. It's not about the Speed itself, but about the overall Capacity with Extreme Load while keeping consistant Speed. In the future I will keep adding new blog entries around this topic, with some sample codes experiences sharing that I capture in the last few years. In the meanwhile if you want to know more how Oracle Coherence, I strongly suggest you to start with checking how our worldwide customers are using Oracle Coherence first, then you can start playing with the product through our tutorial.Have Fun !

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• Thinking differently about BI delivery

  - by jamiet

  My day job involves implementing Business Intelligence (BI) solutions which, as I have said before, is simply about giving people the information they need to do their jobs. I’m always interested in learning about new ways of achieving that aim and that is my motivation for writing blog entries that are not concerned with SQL or SQL Server per se. Implementing BI systems usually involves hacking together a bunch third party products with some in-house “glue” and delivering information using some shiny, expensive web-based front-end tool; the list of vendors that supply such tools is big and ever-growing. No doubt these tools have their place and of late I have started to wonder whether they can be supplemented with different ways of delivering information. The problem I have with these separate web-based tools is exactly that – they are separate web-based tools. What’s the problem with that you might ask? I’ll explain! They force the information worker to go somewhere unfamiliar in order to get the information they need to do their jobs. Would it not be better if we could deliver information into the tools that those information workers are already using and not force them to go somewhere else? I look at the rise of blogging over recent years and I realise that what made them popular is that people can subscribe to RSS feeds and have information pushed to them in their tool of choice rather than them having to go and find the information for themselves in a tool that has been foisted upon them. Would it not be a good idea to adopt the principle of subscription for the benefit of delivering BI information as well? I think it would and in the rest of this blog entry I’ll outline such a scenario where the power of subscription could be used to enhance the delivery of information to information workers. Typical questions that information workers ask might be: What are my year-on-year sales figures? What was my footfall yesterday? How many widgets have I sold so far today? Each of those questions includes a time element and that shouldn’t surprise us, any BI system that I have worked on includes the dimension of time. Now, what do people use to view and organise their time-oriented information? Its not a trick question, they use a calendar and in the enterprise space more often than not that calendar is managed using Outlook. Given then that information workers are already looking at their calendar in Outlook anyway would it not make sense then to deliver information into that same calendar? Of course it would. Calendars are a great way of visualising information such as sales figures. Observe: Just in this single screenshot I have managed to convey a multitude of information. The information worker can see, at a glance, information about hourly/daily/weekly/monthly sales and, moreover, he/she is viewing that information right inside the tool that they use every day. There is no effort on the part of him/her, the information just appears hour after hour, day after day. Taking the idea further, each one of those calendar items could be a mini-dashboard in its own right. Double-clicking on an item could show a plethora of other information about that time slot such as breaking the sales down per region or year-over-year comparisons. Perhaps the title could employ a sparkline? Loads of possibilities. The point is that calendars are a completely natural way to visualise information; we should make more use of them! The real beauty of delivering information using calendars for us BI developers is that it should be so easy. In the case of Outlook we don’t need to write complicated VBA code that can go and manipulate a person’s calendar, simply publishing data in a format that Outlook can understand is sufficient and happily such formats already exist; iCalendar is the accepted format and the even more flexible xCalendar is hopefully on its way as well.   I’d like to make one last point and this one is with my SQL Server hat on. Reporting Services 2008 R2 introduced the ability to publish data as subscribable Atom feeds so it seems logical that it could also be a vehicle for delivering calendar feeds too. If you think this would be a good idea go and vote for it at Publish data as iCalendar feeds and please please please add some comments (especially if you vote it down). Work smarter, not harder! @Jamiet Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Lessons learnt in implementing Scrum in a Large Organization that has traditional values

  - by MarkPearl

  I recently had the experience of being involved in a “test” scrum implementation in a large organization that was used to a traditional project management approach. Here are some lessons that I learnt from it. Don’t let the Project Manager be the Product Owner First lesson learnt is to identify the correct product owner – in this instance the product manager assumed the role of the product owner which was a mistake. The product owner is the one who has the most to loose if the project fails. With a methodology that advocates removing the role of the project manager from the process then it is not in the interests of the person who is employed as a project manager to be the product owner – in fact they have the most to gain should the project fail. Know the time commitments of team members to the Project Second lesson learnt is to get a firm time commitment of the members on a team for the sprint and to hold them to it. In this project instance many of the issues we faced were with team members having to double up on supporting existing projects/systems and the scrum project. In many situations they just didn’t get round to doing any work on the scrum project for several days while they tried to meet other commitments. Initially this was not made transparent to the team – in stand up team members would say that had done some work but would be very vague on how much time they had actually spent using the blackhole of their other legacy projects as an excuse – putting up a time burn down chart made time allocations transparent and easy to hold the team to. In addition, how can you plan for a sprint without knowing the actual time available of the members – when I mean actual time, the exercise of getting them to go through all their appointments and lunch times and breaks and removing them from their time commitment helps get you to a realistic time that they can dedicate. Make sure you meet your minimum team sizes In a recent post I wrote about the difference between a partnership and a team. If you are going to do scrum in a large organization make sure you have a minimum team size of at least 3 developers. My experience with larger organizations is that people have a tendency to be sick more, take more leave and generally not be around – if you have a team size of two it is so easy to loose momentum on the project – the more people you have in the team (up to about 9) the more the momentum the project will have when people are not around. Swapping from one methodology to another can seem as waste to the customer It sounds bad, but most customers don’t care what methodology you use. Often they have bought into the “big plan upfront”. If you can, avoid taking a project on midstream from a traditional approach unless the customer has not bought into the process – with this particular project they had a detailed upfront planning breakaway with the customer using the traditional approach and then before the project started we moved onto a scrum implementation – this seemed as waste to the customer. We should have managed the customers expectation properly. Don’t play the role of the scrum master if you can’t be the scrum master With this particular implementation I was the “scrum master”. But all I did was go through the process of the formal meetings of scrum – I attended stand up, retrospectives and planning – but I was not hands on the ground. I was not performing the most important role of removing blockages – and by the end of the project there were a number of blockages “cropping up”. What could have been a better approach was to take someone on the team and train them to be the scrum master and be present to coach them. Alternatively actually be on the team on a fulltime basis and be the scrum master. By just going through the meetings of scrum didn’t mean we were doing scrum. So we failed with this one, if you fail look at it from an agile perspective As this particular project drew to a close and it became more and more apparent that it was not going to succeed the failure of it became depressing. Emotions were expressed by various people on the team that we not encouraging and enforced the failure. Embracing the failure and looking at it for what it is instead of taking it as the end of the world can change how you grow from the experience. Acknowledging that it failed and then focussing on learning from why and how to avoid the failure in the future can change how you feel emotionally about the team, the project and the organization.

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• Multithreading in lwjgl getting rid of sleep.

  - by pangaea

  I'm trying to use multithreading in my game. However, I can't seem to get rid of the sleep. If I don't it's a blank screen, as there is no time for the computer to actually render the triangleMob as it can't access getArrayList(), in my main class I have a TriangleMob arraylist. If I delay it, then it can access the previousMob and it renders. If I don't, then it's blank screen. Can I get rid of the delay? Also, is this a bad way to multithread? Surely, this should be fast. I need multithreading so can you please not suggest not using it. public class TriangleMob extends Thread implements Runnable { private static int count=0; private int objectDisplayList; private static ArrayList<TriangleMob> previousMob = new ArrayList<TriangleMob>(); private static ArrayList<TriangleMob> currentMob = new ArrayList<TriangleMob>(); private static ArrayList<TriangleMob> laterMob = new ArrayList<TriangleMob>(); private Vector3f position = new Vector3f(0f,0f,0f); private Vector3f movement = new Vector3f(0f,0f,0f); public TriangleMob() { // Create the display list CreateDisplayList(); count++; } public TriangleMob(Vector3f position) { // Create the display list CreateDisplayList(); this.position = position; count++; } private void CreateDisplayList() { objectDisplayList = glGenLists(1); glNewList(objectDisplayList, GL_COMPILE); { double topPoint = 0.75; glBegin(GL_TRIANGLES); glColor4f(1, 1, 0, 1f); glVertex3d(0, topPoint, -5); glColor4f(0, 0, 1, 1f); glVertex3d(-1, -0.75, -4); glColor4f(0, 0, 1, 1f); glVertex3d(1, -.75, -4); glColor4f(1, 1, 0, 1f); glVertex3d(0, topPoint, -5); glColor4f(0, 0, 1, 1f); glVertex3d(1, -0.75, -4); glColor4f(0, 0, 1, 1f); glVertex3d(1, -0.75, -6); glColor4f(1, 1, 0, 1f); glVertex3d(0, topPoint, -5); glColor4f(0, 0, 1, 1f); glVertex3d(1, -0.75, -6); glColor4f(0, 0, 1, 1f); glVertex3d(-1, -.75, -6); glColor4f(1, 1, 0, 1f); glVertex3d(0, topPoint, -5); glColor4f(0, 0, 1, 1f); glVertex3d(-1, -0.75, -6); glColor4f(0, 0, 1, 1f); glVertex3d(-1, -.75, -4); glEnd(); glColor4f(1, 1, 1, 1); } glEndList(); } public static int getCount() { return count; } public Vector3f getMovement() { return movement; } public Vector3f getPosition() { return position; } public synchronized int getObjectList() { return objectDisplayList; } public synchronized static ArrayList<TriangleMob> getArrayList(){ if(previousMob != null) { return previousMob; } previousMob.add(new TriangleMob()); return previousMob; } public synchronized void move(Vector3f movement) { // If you want to move in all 3 axis position.x += movement.x; position.y += movement.y; position.z += movement.z; } public synchronized void render() { glPushMatrix(); glTranslatef(-position.x, -position.y, -position.z); glCallList(objectDisplayList); glPopMatrix(); } public synchronized static void setTriangleMob(ArrayList<TriangleMob> triangleMobSet) { laterMob = triangleMobSet; } private synchronized void setPreTriangleMob(ArrayList<TriangleMob> currentMob2) { previousMob = currentMob2; } public void run(){ while(true) { if(laterMob == null) { currentMob = laterMob; System.out.println("Copying"); } for(int i=0; i<currentMob.size(); i++) { currentMob.get(i).move(new Vector3f(0.1f,0.01f,0.01f)); } setPreTriangleMob(currentMob); try { sleep(1L); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }

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• The sign of a true manager is delegation (C# style)

  - by MarkPearl

  Today I thought I would write a bit about delegates in C#. Up till recently I have managed to side step any real understanding of what delegates do and why they are useful – I mean, I know roughly what they do and have used them a lot, but I have never really got down dirty with them and mucked about. Recently however with my renewed interest in Silverlight delegates came up again as a possible solution to a particular problem, and suddenly I found myself opening a bland little console application to just see exactly how far I could take delegates with my limited knowledge. So, let’s first look at the MSDN definition of delegates… A delegate declaration defines a reference type that can be used to encapsulate a method with a specific signature. A delegate instance encapsulates a static or an instance method. Delegates are roughly similar to function pointers in C++; however, delegates are type-safe and secure. Well, don’t you love MSDN for such a useful definition. I must give it credit though… later on it really explains it a bit better by saying “A delegate lets you pass a function as a parameter. The type safety of delegates requires the function you pass as a delegate to have the same signature as the delegate declaration.” A little more reading up on delegates mentions that delegates are similar to interfaces in that they enable the separation of specification and implementation. A delegate declares a single method, while an interface declares a group of methods. So enough reading - lets look at some code and see a basic example of a delegate… Let’s assume we have a console application with a simple delegate declared called AdjustValue like below… class Program { private delegate int AdjustValue(int val); static void Main(string[] args) { } } In a sense, all we have said is that we will be creating one or more methods that follow the same pattern as AdjustValue – i.e. they will take one input value of type int and return an integer. We could then expand our code to have various methods that match the structure of our delegate AdjustValue (remember the structure is int xxx (int xxx)) class Program { private delegate int AdjustValue(int val); private static int Dbl(int val) { return val * 2; } private static int AlwaysOne(int val) { return 1; } static void Main(string[] args) { } }  Above I have expanded my project to have two methods, one called Dbl and the other AlwaysOne. Dbl always returns double the input val and AlwaysOne always returns 1. I could now declare a variable and assign it to be one of those functions, like the following… class Program { private delegate int AdjustValue(int val); private static int Dbl(int val) { return val * 2; } private static int AlwaysOne(int val) { return 1; } static void Main(string[] args) { AdjustValue myDelegate; myDelegate = Dbl; Console.WriteLine(myDelegate(1).ToString()); Console.ReadLine(); } } In this instance I have declared an instance of the AdjustValue delegate called myDelegate; I have then told myDelegate to point to the method Dbl, and then called myDelegate(1). What would the result be? Yes, in this instance it would be exactly the same as me calling the following code… static void Main(string[] args) { Console.WriteLine(Dbl(1).ToString()); Console.ReadLine(); }   So why all the extra work for delegates when we could just do what we did above and call the method directly? Well… that separation of specification to implementation comes to mind. So, this all seems pretty simple. Let’s take a slightly more complicated variation to the console application. Assume that my project is the same as the one previously except that my main method is adjusted as follows… static void Main(string[] args) { AdjustValue myDelegate; myDelegate = Dbl; myDelegate = AlwaysOne; Console.WriteLine(myDelegate(1).ToString()); Console.ReadLine(); } What would happen in this scenario? Quite simply “1” would be written to the console, the reason being that myDelegate was last pointing to the AlwaysOne method before it was called. Make sense? In a way, the myDelegate is a variable method that can be swapped and changed when needed. Let’s make the code a little more confusing by using a delegate in the declaration of another delegate as shown below… class Program { private delegate int AdjustValue(InputValue val); private delegate int InputValue(); private static int Dbl(InputValue val) { return val()*2; } private static int GetInputVal() { Console.WriteLine("Enter a whole number : "); return Convert.ToInt32(Console.ReadLine()); } static void Main(string[] args) { AdjustValue myDelegate; myDelegate = Dbl; Console.WriteLine(myDelegate(GetInputVal).ToString()); Console.ReadLine(); } }   Now it gets really interesting because it looks like we have passed a method into a function in the main method by declaring… Console.WriteLine(myDelegate(GetInputVal).ToString()); So, what it the output? Well, try take a guess on what will happen – then copy the code and see if you got it right. Well that brings me to the end of this short explanation of Delegates. Hopefully it made sense!

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• Processing Text and Binary (Blob, ArrayBuffer, ArrayBufferView) Payload in WebSocket - (TOTD #185)

  - by arungupta

  The WebSocket API defines different send(xxx) methods that can be used to send text and binary data. This Tip Of The Day (TOTD) will show how to send and receive text and binary data using WebSocket. TOTD #183 explains how to get started with a WebSocket endpoint using GlassFish 4. A simple endpoint from that blog looks like: @WebSocketEndpoint("/endpoint") public class MyEndpoint { public void receiveTextMessage(String message) { . . . } } A message with the first parameter of the type String is invoked when a text payload is received. The payload of the incoming WebSocket frame is mapped to this first parameter. An optional second parameter, Session, can be specified to map to the "other end" of this conversation. For example: public void receiveTextMessage(String message, Session session) {     . . . } The return type is void and that means no response is returned to the client that invoked this endpoint. A response may be returned to the client in two different ways. First, set the return type to the expected type, such as: public String receiveTextMessage(String message) { String response = . . . . . . return response; } In this case a text payload is returned back to the invoking endpoint. The second way to send a response back is to use the mapped session to send response using one of the sendXXX methods in Session, when and if needed. public void receiveTextMessage(String message, Session session) {     . . .     RemoteEndpoint remote = session.getRemote();     remote.sendString(...);     . . .     remote.sendString(...);    . . .    remote.sendString(...); } This shows how duplex and asynchronous communication between the two endpoints can be achieved. This can be used to define different message exchange patterns between the client and server. The WebSocket client can send the message as: websocket.send(myTextField.value); where myTextField is a text field in the web page. Binary payload in the incoming WebSocket frame can be received if ByteBuffer is used as the first parameter of the method signature. The endpoint method signature in that case would look like: public void receiveBinaryMessage(ByteBuffer message) {     . . . } From the client side, the binary data can be sent using Blob, ArrayBuffer, and ArrayBufferView. Blob is a just raw data and the actual interpretation is left to the application. ArrayBuffer and ArrayBufferView are defined in the TypedArray specification and are designed to send binary data using WebSocket. In short, ArrayBuffer is a fixed-length binary buffer with no format and no mechanism for accessing its contents. These buffers are manipulated using one of the views defined by one of the subclasses of ArrayBufferView listed below: Int8Array (signed 8-bit integer or char) Uint8Array (unsigned 8-bit integer or unsigned char) Int16Array (signed 16-bit integer or short) Uint16Array (unsigned 16-bit integer or unsigned short) Int32Array (signed 32-bit integer or int) Uint32Array (unsigned 16-bit integer or unsigned int) Float32Array (signed 32-bit float or float) Float64Array (signed 64-bit float or double) WebSocket can send binary data using ArrayBuffer with a view defined by a subclass of ArrayBufferView or a subclass of ArrayBufferView itself. The WebSocket client can send the message using Blob as: blob = new Blob([myField2.value]);websocket.send(blob); where myField2 is a text field in the web page. The WebSocket client can send the message using ArrayBuffer as: var buffer = new ArrayBuffer(10);var bytes = new Uint8Array(buffer);for (var i=0; i<bytes.length; i++) { bytes[i] = i;}websocket.send(buffer); A concrete implementation of receiving the binary message may look like: @WebSocketMessagepublic void echoBinary(ByteBuffer data, Session session) throws IOException {    System.out.println("echoBinary: " + data);    for (byte b : data.array()) {        System.out.print(b);    }    session.getRemote().sendBytes(data);} This method is just printing the binary data for verification but you may actually be storing it in a database or converting to an image or something more meaningful. Be aware of TYRUS-51 if you are trying to send binary data from server to client using method return type. Here are some references for you: JSR 356: Java API for WebSocket - Specification (Early Draft) and Implementation (already integrated in GlassFish 4 promoted builds) TOTD #183 - Getting Started with WebSocket in GlassFish TOTD #184 - Logging WebSocket Frames using Chrome Developer Tools, Net-internals and Wireshark Subsequent blogs will discuss the following topics (not necessary in that order) ... Error handling Custom payloads using encoder/decoder Interface-driven WebSocket endpoint Java client API Client and Server configuration Security Subprotocols Extensions Other topics from the API

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• Adventures in Windows 8: Solving activation errors

  - by Laurent Bugnion

  Note: I tagged this article with “MVVM” because I got a few support requests for MVVM Light regarding this exact issue. In fact it is a Windows 8 issue and has nothing to do with MVVM Light per se… Sometimes when you work on a Windows 8 app, you will get a very annoying issue when starting the app. In that case, the app doesn’t not even start past the Splash screen. Putting a breakpoint in App.xaml.cs doesn’t help because the app doesn’t even reach that point! So what exactly is happening? Well when a Windows 8 app starts, the system is performing a few check first. One of the checks, for instance, is to see if an app with the same package ID is already available. The package ID is a unique value set in the package manifest. In the Solution Explorer, double click on Package.appxmanifest. This opens the manifest in a special editor Click on the Packaging tab See the GUID under Package Name. This is the unique ID I am talking about. If there is a conflict (i.e. if an app is already installed with the exact same ID), Windows will warm the user that the app is already installed. However when you are in the process of developing an app, you install and uninstall the same app many many times (every time that you start in Visual Studio), and sometimes some issues arise, for instance failing to uninstall the app before starting the new instance of the same app. First step if you get such an error When the application fails to start past the splash screen, the first step is to identify what kind of error happened. In my experience the “already installed” is by far the most frequent (in fact I never had another such error), but it can be something else. An annoying thing is that the popup that shows the error is usually started below the Windows 8 app, and so you don’t even see it! This is especially true if you run this in the Simulator. In that case, do the following: Press on the Simulator’s home button, then press on the Desktop tile on the Start menu. The error popup should be shown on the desktop. If your applications runs on the Local machine, you also do the same and press the Windows button, and then from the Start menu press the Desktop tile. Deployment error in Studio Sometimes the same error causes Visual Studio to fail launching the application at all with a deployment error. This is a better case, because at least it is clear that there is an issue. In that case, write down the code that is shown in the Error window (for instance 0x80073D05 in the example below). Once you have the error code, go to the “Troubleshooting packaging, deployment, and query of Windows Store apps” page and look up the code in question. In my case, the error was “ERROR_DELETING_EXISTING_APPLICATIONDATA_STORE_FAILED”, “An error occurred while deleting the package's previously existing application data.” Solving the “ERROR_DELETING_EXISTING_APPLICATIONDATA_STORE_FAILED” issue Update: Before trying the below, you can also try the simple steps: Exit Visual Studio Go to the Start menu Locate your app’s tile. It should be visible in the Start menu directly, towards the far end on the right. Right click the tile and select Uninstall from the App Bar. Restart Visual Studio and try again. Sometimes it helps. If it doesn’t, then try the following: In order to solve the case where Windows, for any reason, fails to delete the existing application before starting the new instance, follow the steps: Open the Package.appxmanifest in Visual Studio Open the Packaging tab. Change the Package name. For tests you can just try to change the last character of the GUID, though I would recommend creating a brand new GUID. Press Start Type GUID Start the GUID Generator application Select Registry Format Press Copy. Paste the new GUID in place of the Package Name in Visual Studio Important: don’t forget to remove the curly brackets at the beginning and at the end of the newly pasted GUID. Then you just have to cross your fingers and start the application again… If it works, celebrate. if it doesn’t work… well at this point I am not sure so good luck with that ;) Happy coding, Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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• Encrypt images before uploading to Dropbox [migrated]

  - by Cherry

  I want to encrypt a file first before the file will be uploaded to the dropbox. So i have implement the encryption inside the uploading of the codes. However, there is an error after i integrate the codes together. Where did my mistake go wrong? Error at putFileOverwriteRequest and it says The method putFileOverwriteRequest(String, InputStream, long, ProgressListener) in the type DropboxAPI is not applicable for the arguments (String, FileOutputStream, long, new ProgressListener(){}) Another problem is that this FileOutputStream fis = new FileOutputStream(new File("dont know what to put in this field")); i do not know where to put the file so that after i read the file, it will call the path and then upload to the Dropbox. Anyone is kind to help me in this? As time is running out for me and i still cant solve the problem. Thank you in advance. The full code is as below. public class UploadPicture extends AsyncTask<Void, Long, Boolean> { private DropboxAPI<?> mApi; private String mPath; private File mFile; private long mFileLen; private UploadRequest mRequest; private Context mContext; private final ProgressDialog mDialog; private String mErrorMsg; public UploadPicture(Context context, DropboxAPI<?> api, String dropboxPath, File file) { // We set the context this way so we don't accidentally leak activities mContext = context.getApplicationContext(); mFileLen = file.length(); mApi = api; mPath = dropboxPath; mFile = file; mDialog = new ProgressDialog(context); mDialog.setMax(100); mDialog.setMessage("Uploading " + file.getName()); mDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); mDialog.setProgress(0); mDialog.setButton("Cancel", new OnClickListener() { public void onClick(DialogInterface dialog, int which) { // This will cancel the putFile operation mRequest.abort(); } }); mDialog.show(); } @Override protected Boolean doInBackground(Void... params) { try { KeyGenerator keygen = KeyGenerator.getInstance("DES"); SecretKey key = keygen.generateKey(); //generate key //encrypt file here first byte[] plainData; byte[] encryptedData; Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding"); cipher.init(Cipher.ENCRYPT_MODE, key); //File f = new File(mFile); //read file FileInputStream in = new FileInputStream(mFile); //obtains input bytes from a file plainData = new byte[(int)mFile.length()]; in.read(plainData); //Read bytes of data into an array of bytes encryptedData = cipher.doFinal(plainData); //encrypt data FileOutputStream fis = new FileOutputStream(new File("dont know what to put in this field")); //upload to a path first then call the path so that it can be uploaded up to the dropbox //save encrypted file to dropbox // By creating a request, we get a handle to the putFile operation, // so we can cancel it later if we want to //FileInputStream fis = new FileInputStream(mFile); String path = mPath + mFile.getName(); mRequest = mApi.putFileOverwriteRequest(path, fis, mFile.length(), new ProgressListener() { @Override public long progressInterval() { // Update the progress bar every half-second or so return 500; } @Override public void onProgress(long bytes, long total) { publishProgress(bytes); } }); if (mRequest != null) { mRequest.upload(); return true; } } catch (DropboxUnlinkedException e) { // This session wasn't authenticated properly or user unlinked mErrorMsg = "This app wasn't authenticated properly."; } catch (DropboxFileSizeException e) { // File size too big to upload via the API mErrorMsg = "This file is too big to upload"; } catch (DropboxPartialFileException e) { // We canceled the operation mErrorMsg = "Upload canceled"; } catch (DropboxServerException e) { // Server-side exception. These are examples of what could happen, // but we don't do anything special with them here. if (e.error == DropboxServerException._401_UNAUTHORIZED) { // Unauthorized, so we should unlink them. You may want to // automatically log the user out in this case. } else if (e.error == DropboxServerException._403_FORBIDDEN) { // Not allowed to access this } else if (e.error == DropboxServerException._404_NOT_FOUND) { // path not found (or if it was the thumbnail, can't be // thumbnailed) } else if (e.error == DropboxServerException._507_INSUFFICIENT_STORAGE) { // user is over quota } else { // Something else } // This gets the Dropbox error, translated into the user's language mErrorMsg = e.body.userError; if (mErrorMsg == null) { mErrorMsg = e.body.error; } } catch (DropboxIOException e) { // Happens all the time, probably want to retry automatically. mErrorMsg = "Network error. Try again."; } catch (DropboxParseException e) { // Probably due to Dropbox server restarting, should retry mErrorMsg = "Dropbox error. Try again."; } catch (DropboxException e) { // Unknown error mErrorMsg = "Unknown error. Try again."; } catch (FileNotFoundException e) { } return false; } @Override protected void onProgressUpdate(Long... progress) { int percent = (int)(100.0*(double)progress[0]/mFileLen + 0.5); mDialog.setProgress(percent); } @Override protected void onPostExecute(Boolean result) { mDialog.dismiss(); if (result) { showToast("Image successfully uploaded"); } else { showToast(mErrorMsg); } } private void showToast(String msg) { Toast error = Toast.makeText(mContext, msg, Toast.LENGTH_LONG); error.show(); } }

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• c# display DB table structure

  - by user3529643

  I have a question. My code is the following : public partial class Form1 : Form { public OleDbConnection datCon; public string MyDataFile; public ArrayList tblArray; public ArrayList fldArray; public Form1() { InitializeComponent(); lvData.Clear(); lvData.View = View.Details; lvData.LabelEdit = false; lvData.FullRowSelect = true; lvData.GridLines = true; } private void DataConnection() { MyDataFile = Application.StartupPath + @"\studenti.mdb"; string MyCon = @"provider=microsoft.jet.oledb.4.0;data source=" + MyDataFile; try { datCon = new OleDbConnection(MyCon); } catch (Exception ex) { MessageBox.Show(ex.Message); } FillTreeView(); } private void GetTables(OleDbConnection cnn) { try { cnn.Open(); DataTable schTable = cnn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new Object[] { null, null, null, "TABLE" }); tblArray = new ArrayList(); foreach (DataRow datrow in schTable.Rows) { tblArray.Add(datrow["TABLE_NAME"].ToString()); } cnn.Close(); } catch (Exception ex) { MessageBox.Show(ex.Message); } } private void GetFields(OleDbConnection cnn, string tabNode) { string tabName; try { tabName = tabNode; cnn.Open(); DataTable schTable = cnn.GetOleDbSchemaTable(OleDbSchemaGuid.Columns, new Object[] { null, null, tabName }); fldArray = new ArrayList(); foreach (DataRow datRow in schTable.Rows) { fldArray.Add(datRow["COLUMN_NAME"].ToString()); } cnn.Close(); } catch (Exception ex) { MessageBox.Show(ex.Message); } } private void FillTreeView() { tvData.Nodes.Clear(); tvData.Nodes.Add("Database"); tvData.Nodes[0].Tag = "RootDB"; GetTables(datCon); // add table node for (int i = 0; i < tblArray.Count; i++) { tvData.Nodes[0].Nodes.Add(tblArray[i].ToString()); tvData.Nodes[0].Nodes[i].Tag = "Tables"; } // add field node for (int i = 0; i < tblArray.Count; i++) { GetFields(datCon, tblArray[i].ToString()); for (int j = 0; j < fldArray.Count; j++) { tvData.Nodes[0].Nodes[i].Nodes.Add(fldArray[j].ToString()); tvData.Nodes[0].Nodes[i].Nodes[j].Tag = "Fields"; } } this.tvData.ContextMenuStrip = contextMenuStrip1; contextMenuStrip1.ItemClicked +=contextMenuStrip1_ItemClicked; } public void FillListView(OleDbConnection cnn, string tabName) { OleDbCommand cmdRead; OleDbDataReader datReader; string strField; lblTableName.Text = tabName; strField = "SELECT * FROM [" + tabName + "]"; // Initi cmdRead obiect cmdRead = new OleDbCommand(strField, cnn); cnn.Open(); datReader = cmdRead.ExecuteReader(); // fill ListView while (datReader.Read()) { ListViewItem objListItem = new ListViewItem(datReader.GetValue(0).ToString()); for (int c = 1; c < datReader.FieldCount; c++) { objListItem.SubItems.Add(datReader.GetValue(c).ToString()); } lvData.Items.Add(objListItem); } datReader.Close(); cnn.Close(); } private void ViewToolStripMenuItem_Click(object sender, EventArgs e) { DataConnection(); } public void tvData_AfterExpand(object sender, System.Windows.Forms.TreeViewEventArgs e) { string tabName; int fldCount; if (e.Node.Tag.ToString() == "Tables") { fldCount = e.Node.GetNodeCount(false); //column headers. int n = lvData.Width; double wid = n / fldCount; // width columnn for (int c = 0; c < fldCount; c++) { lvData.Columns.Add(e.Node.Nodes[c].Text, (int)wid, HorizontalAlignment.Left); } // gett table name tabName = e.Node.Text; FillListView(datCon, tabName); } } public void button1_Click(object sender, EventArgs e) { //TO DO?? } } I have a treeview populated with tables (nodes) from my database, and a listview which is populated with the data from my tables when I click on a table. As you can see I have a button1 on my form. When I click it I want it to display to me the structure of the table I selected in my treeview (a treeview node). Not too many details, just the name of the columns in my table, type of columns, primary keys. I've tried to follow many tutorials but I can t seem to manage it.

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• How to move a rectangle properly?

  - by bodycountPP

  I recently started to learn OpenGL. Right now I finished the first chapter of the "OpenGL SuperBible". There were two examples. The first had the complete code and showed how to draw a simple triangle. The second example is supposed to show how to move a rectangle using SpecialKeys. The only code provided for this example was the SpecialKeys method. I still tried to implement it but I had two problems. In the previous example I declared and instaciated vVerts in the SetupRC() method. Now as it is also used in the SpecialKeys() method, I moved the declaration and instantiation to the top of the code. Is this proper c++ practice? I copied the part where vertex positions are recalculated from the book, but I had to pick the vertices for the rectangle on my own. So now every time I press a key for the first time the rectangle's upper left vertex is moved to (-0,5:-0.5). This ok because of GLfloat blockX = vVerts[0]; //Upper left X GLfloat blockY = vVerts[7]; // Upper left Y But I also think that this is the reason why my rectangle is shifted in the beginning. After the first time a key was pressed everything works just fine. Here is my complete code I hope you can help me on those two points. GLBatch squareBatch; GLShaderManager shaderManager; //Load up a triangle GLfloat vVerts[] = {-0.5f,0.5f,0.0f, 0.5f,0.5f,0.0f, 0.5f,-0.5f,0.0f, -0.5f,-0.5f,0.0f}; //Window has changed size, or has just been created. //We need to use the window dimensions to set the viewport and the projection matrix. void ChangeSize(int w, int h) { glViewport(0,0,w,h); } //Called to draw the scene. void RenderScene(void) { //Clear the window with the current clearing color glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT|GL_STENCIL_BUFFER_BIT); GLfloat vRed[] = {1.0f,0.0f,0.0f,1.0f}; shaderManager.UseStockShader(GLT_SHADER_IDENTITY,vRed); squareBatch.Draw(); //perform the buffer swap to display the back buffer glutSwapBuffers(); } //This function does any needed initialization on the rendering context. //This is the first opportunity to do any OpenGL related Tasks. void SetupRC() { //Blue Background glClearColor(0.0f,0.0f,1.0f,1.0f); shaderManager.InitializeStockShaders(); squareBatch.Begin(GL_QUADS,4); squareBatch.CopyVertexData3f(vVerts); squareBatch.End(); } //Respond to arrow keys by moving the camera frame of reference void SpecialKeys(int key,int x,int y) { GLfloat stepSize = 0.025f; GLfloat blockSize = 0.5f; GLfloat blockX = vVerts[0]; //Upper left X GLfloat blockY = vVerts[7]; // Upper left Y if(key == GLUT_KEY_UP) { blockY += stepSize; } if(key == GLUT_KEY_DOWN){blockY -= stepSize;} if(key == GLUT_KEY_LEFT){blockX -= stepSize;} if(key == GLUT_KEY_RIGHT){blockX += stepSize;} //Recalculate vertex positions vVerts[0] = blockX; vVerts[1] = blockY - blockSize*2; vVerts[3] = blockX + blockSize * 2; vVerts[4] = blockY - blockSize *2; vVerts[6] = blockX+blockSize*2; vVerts[7] = blockY; vVerts[9] = blockX; vVerts[10] = blockY; squareBatch.CopyVertexData3f(vVerts); glutPostRedisplay(); } //Main entry point for GLUT based programs int main(int argc, char** argv) { //Sets the working directory. Not really needed gltSetWorkingDirectory(argv[0]); //Passes along the command-line parameters and initializes the GLUT library. glutInit(&argc,argv); //Tells the GLUT library what type of display mode to use, when creating the window. //Double buffered window, RGBA-Color mode,depth-buffer as part of our display, stencil buffer also available glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA|GLUT_DEPTH|GLUT_STENCIL); //Window size glutInitWindowSize(800,600); glutCreateWindow("MoveRect"); glutReshapeFunc(ChangeSize); glutDisplayFunc(RenderScene); glutSpecialFunc(SpecialKeys); //initialize GLEW library GLenum err = glewInit(); //Check that nothing goes wrong with the driver initialization before we try and do any rendering. if(GLEW_OK != err) { fprintf(stderr,"Glew Error: %s\n",glewGetErrorString); return 1; } SetupRC(); glutMainLoop(); return 0; }

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• What's New in Oracle VM VirtualBox 4.2?

  - by Fat Bloke

  A year is a long time in the IT industry. Since the last VirtualBox feature release, which was a little over a year ago, we've seen: new releases of cool new operating systems, such as Windows 8, ChromeOS, and Mountain Lion; we've seen a myriad of new Linux releases from big Enterprise class distributions like Oracle 6.3, to accessible desktop distros like Ubuntu 12.04 and Fedora 17; and we've also seen the spec of a typical PC or laptop double in power. All of these events have influenced our new VirtualBox version which we're releasing today. Here's how... Powerful hosts  One of the trends we've seen is that as the average host platform becomes more powerful, our users are consistently running more and more vm's. Some of our users have large libraries of vm's of various vintages, whilst others have groups of vm's that are run together as an assembly of the various tiers in a multi-tiered software solution, for example, a database tier, middleware tier, and front-ends.  So we're pleased to unveil a more powerful VirtualBox Manager to address the needs of these users: VM Groups Groups allow you to organize your VM library in a sensible way, e.g.  by platform type, by project, by version, by whatever. To create groups you can drag one VM onto another or select one or more VM's and choose Machine...Group from the menu bar. You can expand and collapse groups to save screen real estate, and you can Enter and Leave a group (think iPad navigation here) by using the right and left arrow keys when groups are selected. But groups are more than passive folders, because you can now also perform operations on groups, rather than all the individual VMs. So if you have a multi-tiered solution you can start the whole stack up with just one click. Autostart Many VirtualBox users run dedicated services in their VMs, for example, running a Wiki. With these types of VM workloads, you really want the VM start up when the host machine boots up. So with 4.2 we've introduced a cross-platform Auto-start mechanism to allow you to treat VMs as host services. Headless VM Launching With VM's such as web servers, wikis, and other types of server-class workloads, the Console of the VM is pretty much redundant. For some time now VirtualBox has offered a separate launch mechanism for these VM's, namely the command-line interface commands VBoxHeadless or VBoxManage startvm ... --type headless commands. But with 4.2 we also allow you launch headless VMs from the Manager. Simply hold down Shift when launching the VM from the Manager.  It's that easy. But how do you stop a headless VM? Well, with 4.2 we allow you to Close the VM from the Manager. (BTW best to use the ACPI Shutdown method which allows the guest VM to close down gracefully.) Easy VM Creation For our expert users, the  New VM Wizard was a little tiresome, so now there's a faster 2-click VM creation mode. Just Hide the description when creating a new VM. Powerful VMs  As the hosts have become more powerful, so are the guests that are running inside them. Here are some of the 4.2 features to accommodate them: Virtual Network Interface Cards  With 4.2, it's now possible to create VMs with up to 36 NICs, when using the ICH9 chipset emulation. But with great power comes great responsibility (didn't Obi-Wan say something similar?), and so we have also introduced bandwidth limiting to prevent a rogue VM stealing the whole pipe. VLAN tagging Some of our users leverage VLANs extensively so we've enhanced the E1000 NICs to support this.  Processor Performance If you are running a CPU which supports Nested Paging (aka EPT in the Intel world) such as most of the Core i5 and i7 CPUs, or are running an AMD Bulldozer or later, you should see some performance improvements from our work with these processors. And while we're talking Processors, we've added support for some of the more modern VIA CPUs too. Powerful Automation Because VirtualBox runs atop a fully blown operating system, it makes sense to leverage the capabilities of the host to run scripts that can drive the guest VMs. Guest Automation was introduced in a prior release but with 4.2 we've revamped the APIs to allow a richer and more powerful set of operations to be executed by the guest. Check out the IGuest APIs in the VirtualBox Programming Guide and Reference (SDK). Powerful Platforms  All the hardcore engineering that has gone into 4.2 has been done for a purpose and that is to deliver a fast and powerful engine that can run almost any x86 OS because of the integrity of the virtualization. So we're pleased to add support for these platforms: Mac OS X "Mountain Lion"  Windows 8 Windows Server 2012 Ubuntu 12.04 (“Precise Pangolin”) Fedora 17 Oracle Linux 6.3  Here's the proof: We don't have time to go into the myriad of smaller improvements such as support for burning audio CDs from a guest, bi-directional clipboard control,  drag-and-drop of files into Linux guests, etc. so we'll leave that as an exercise for the user as soon as you've downloaded from the Oracle or community site and taken a peek at the User Guide. So all in all, a pretty solid release, one that we hope you'll enjoy discovering. - FB 

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• ????: PostgreSQL??Oracle RAC????

  - by Kumiko Fujita

  ?????????????????????????????????????????????????????????????????????????? ????????????????????????? * * * ?????????????????????????????????????DBMS??????????????????????????????DBMS????????????????????????????????????????????? 1. ???? ?????????????????????????????????????????????????????????????????????1?????? ???????????????? ?????????????????????????????DB???????OSS?PostgreSQL?????AP?????DB??????????????????? ???????? ?????10?????????????GB????????????????????????????DB?????????????????????????? ?????????????3,500?????????24????????????????????????????????????? ??AP?????????????????????????????????????????DB??PostgreSQL??????????????????PostgreSQL ????????????????????Vacuum????????????????????????????????????????????????????? ??????????????????PostgreSQL?OSS??????????????????????????????????????????????????DB MS??????Oracle Database 11gR2???????????????????????500GB???????????????????????????Partitioning ???????? Oracle Database Enterprise Edition?????????????????????????????????????????????? ????SAN?????Active/Standby???HA????????????????? 2. ????? 2.1. ???? PostgreSQL??????Oracle??????????????????????????????????????????????????????TEXT????? ????????????????????Oracle??????????????????????????PostgreSQL??csv???????Oracle Database?SQL*Loa der????????????? ??????????????????????????????DB??????????????Windows?Liunx??????????????????????? ????????????????????????????????????????????????? ?????????????PostgreSQL?NULL?????''????????????Oracle Database???????????????????????? ?????????? table { border-collapse: collapse; } th { border: solid 1px #666666; color: #000000; background-color: #ff9999; } td { border: solid 1px #666666; color: #000000; background-color: #ffffff; } ???? PostgreSQL Oracle Database ??? CHAR(n) CHAR(n),CLOB VARCHAR(n) VARCHAR2(n),CLOB TEXT CLOB ??? NUMERIC NUMBER INTEGER NUMBER SMALLINT NUMBER BIGINT NUMBER REAL NUMBER DOUBLE PRECISION NUMBER ??? DATE DATE TIMESTAMP TIMESTAMP ????? Bytea BLOB LOB BFILE/SecureFiles ??? OID ROWID 2.2. ????? ?????????????PostgreSQL?Oracle Database??????????SQL???????????????????????????????????Postg reSQL?LIMIT?OFFSET??Oracle Database?????????????????????? LIMIT,OFFSET???SELECT?????? /* PostgreSQL LIMIT,OFFSET */ SELECT ??? FROM ????? ORDER BY ???? LIMIT 2 OFFSET 5; /* Oracle Database????? */ SELECT ??? FROM (SELECT ???, ROWNUM line_no FROM (SELECT??? FROM ????? OREDR BY ???? ) ) WHERE line_no BETWEEN 6 AND 7; ??????????????????????????????????????????????????????????????????????????? ?????????????????? ????????????????????????????????????????????????Oracle Database??????????????????????Oracle Database????WHERE??????????????????????????????????????????????????????WHERE?????????????????????? 3. ???? ???????????????????????30%~40%????????????????????80%????????????????????? ?ITpro???:???????4????? ??????????????????????????????????? ·?????·??????????????????????????? ·????????????????????????????? ????????????????????????????????????????? 3.1. ??????? ????????????????????????????????????????·??????????????????????????????????? ???????????????????????????????????????????????????????·?????????????????? ???????????????????????????? (1)???????????????????? (2)???????????????????????????????????????????? (3)??????????????? (4)???????????????????????????????? ???????????·???????????????????????????????????????????????????????????????? ????????????????????? ????????·?? table { border-collapse: collapse; } th { border: solid 1px #666666; color: #000000; background-color: #ff9999; } td { border: solid 1px #666666; color: #000000; background-color: #ffffff; } ?? ?? ?? (1) ?????????? ????????????·???????????????????????? (2) ???????????????????? ?????????????????????????????? (3) ?????4????????????????? ???????????????????????DB????????? (4) ??????????(3)???????? ???????????????????????? ?????????????????????GB???????????????????????????????????????????(3)?????????? ??????? ??????????????????????????????????????????????csv??????????SQL*Loader?Oracle Database?????????????????????Oracle Database???????????????????????????INSERT????????????? ???????????????????????????????????????????????????????????????????????????? ?????????????????????? 3.2. ????? ???????????????????????????????????????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? 3.3. ????? ??????????????????????????????????????????????????????????????????????????? ??????????????????????? DBMS????????????????????????SQL??????????????????????????????????????????????????PostgreSQL?Oracle Database???????????MVCC?????????????????????????Read Committed??????????????????????????????????????????????????????????????????????????????????? ????????????????DBMS?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? 4. ??? PostgreSQL??Oracle Database?????????????????????????????? ????????????·????????????????????????????????????? ??????4???????????????????????·??????????????????? ???????????????????????????????????????????????? ?????????????????????????????????????????????DBMS???????????????????DBMS???????? ?????SQL?????????????????????????????DB???????????????????????????? ???????????????????????????DBMS?????????????????????????????????????????????????????? ??????????????????????????????

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• Why does Cacti keep waiting for dead poller processes?

  - by Oliver Salzburg

  sorry for the length I am currently setting up a new Debian (6.0.5) server. I put Cacti (0.8.7g) on it yesterday and have been battling with it ever since. Initial issue The initial issue I was observing, was that my graphs weren't updating. So I checked my cacti.log and found this concerning message: POLLER: Poller[0] Maximum runtime of 298 seconds exceeded. Exiting. That can't be good, right? So I went checking and started poller.php myself (via sudo -u www-data php poller.php --force). It will pump out a lot of message (which all look like what I would expect) and then hang for a minute. After that 1 minute, it will loop the following message: Waiting on 1 of 1 pollers. This goes on for 4 more minutes until the process is forcefully ended for running longer than 300s. So far so good I went on for a good hour trying to determine what poller might still be running, until I got to the conclusion that there simply is no running poller. Debugging I checked poller.php to see how that warning is issued and why. On line 368, Cacti will retrieve the number of finished processes from the database and use that value to calculate how many processes are still running. So, let's see that value! I added the following debug code into poller.php: print "Finished: " . $finished_processes . " - Started: " . $started_processes . "\n"; Result This will print the following within seconds of starting poller.php: Finished: 0 - Started: 1 Waiting on 1 of 1 pollers. Finished: 1 - Started: 1 So the values are being read and are valid. Until we get to the part where it keeps looping: Finished: - Started: 1 Waiting on 1 of 1 pollers. Suddenly, the value is gone. Why? Putting var_dump() in there confirms the issue: NULL Finished: - Started: 1 Waiting on 1 of 1 pollers. The return value is NULL. How can that be when querying SELECT COUNT()...? (SELECT COUNT() should always return one result row, shouldn't it?) More debugging So I went into lib\database.php and had a look at that db_fetch_cell(). A bit of testing confirmed, that the result set is actually empty. So I added my own database query code in there to see what that would do: $finished_processes = db_fetch_cell("SELECT count(*) FROM poller_time WHERE poller_id=0 AND end_time>'0000-00-00 00:00:00'"); print "Finished: " . $finished_processes . " - Started: " . $started_processes . "\n"; $mysqli = new mysqli("localhost","cacti","cacti","cacti"); $result = $mysqli->query("SELECT COUNT(*) FROM poller_time WHERE poller_id=0 AND end_time>'0000-00-00 00:00:00';"); $row = $result->fetch_assoc(); var_dump( $row ); This will output Finished: - Started: 1 array(1) { ["COUNT(*)"]=> string(1) "2" } Waiting on 1 of 1 pollers. So, the data is there and can be accessed without any problems, just not with the method Cacti is using? Double-check that! I enabled MySQL logging to make sure I'm not imagining things. Sure enough, when the error message is looped, the cacti.log reads as if it was querying like mad: 06/29/2012 08:44:00 PM - CMDPHP: Poller[0] DEVEL: SQL Cell: "SELECT count(*) FROM cacti.poller_time WHERE poller_id=0 AND end_time>'0000-00-00 00:00:00'" 06/29/2012 08:44:01 PM - CMDPHP: Poller[0] DEVEL: SQL Cell: "SELECT count(*) FROM cacti.poller_time WHERE poller_id=0 AND end_time>'0000-00-00 00:00:00'" 06/29/2012 08:44:02 PM - CMDPHP: Poller[0] DEVEL: SQL Cell: "SELECT count(*) FROM cacti.poller_time WHERE poller_id=0 AND end_time>'0000-00-00 00:00:00'" But none of these queries are logged my MySQL. Yet, when I add my own database query code, it shows up just fine. What the heck is going on here?

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• Integrating HP Systems Insight Manager into an existing environment

  - by ewwhite

  I'm working with an environment that spans multiple data centers/sites and consists primarily of HP ProLiant servers (G5-G7) running Linux. The mix is 30% RHEL/CentOS, the rest are Gentoo :(. I also have a few dozen virtual machines running back-office and Windows servers on VMWare ESX hosts. I run OpenNMS to pull SNMP data from the various server nodes and networking devices. While OpenNMS works wonderfully for up/down, thresholds and notifications, it's native handling of traps is a little rough and the graphs are not particularly pretty. I use Orca/RRD graphs for performance trending and nice graphs. I'm tasked with inventorying the environment and wanted to come up with a clean way to organize server information. Since my environment is mostly HP, I've been playing with HP Systems Insight Manager as a way to extract server data and to deploy HP health/monitoring packages and firmware. The Gentoo systems eventually have to be converted to CentOS, so getting a quick assessment of what hardware is where would be great. Although I've read through a few hundred pages of HP manuals, I'm having a difficult time understanding how to get HP SIM to do what I want, though. My main problems are: I have about 40 subnets to deal with; 98% connected with private lines to facilities across the globe. I don't want to initiate an HP SIM discovery only to pull back every piece of intermediate networking hardware and equipment from all of the locations. I'd like this to focus on the servers. I have OpenNMS configured to accept traps. I don't want HP SIM to duplicate that effort. It seems like the built-in software deployment tool wants to overwrite the trapsink parameters for the systems it encounters during discovery. I have about 10 administrative username/password combinations in use across this infrastructure. Is there a more efficient way to get HP SIM to do the discovery or break discovery into manageable chunks? In terms of general workflow, do people typically install the HP Management Agents during the initial OS deployment (e.g. kickstart post script) or afterwards from HP SIM? Is HP SIM too thick/fat to be an inventory tool? I can't tell if it's meant to be used standalone or alongside other monitoring products. Since the majority of the systems I'm trying to track are those running Gentoo (in order to plan the move to CentOS), is there any way for HP SIM to extract system model information from them ( like dmidecode)? I have systems here where I may have an SSH key established, but not direct user or login access. Is there a way for me to import an SSH private/public key pair into HP SIM to reach out to the servers that can't accept standard credentials? There are a handful of sites where I have inconsistent access or have a double-NAT situation. I may be able to poke a server, but it may not be able to find its way back to the management system. Is there a workaround for this? The certificate configuration for HP SIM seems complicated. What is the preferred setup for trust between systems? I'd also appreciate any notes or recommendations to using this product. Or if there's a better way to do this, I'd like to know.

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• proftpd, dynamic IP, and filezilla: port troubles

  - by Yami

  The basic setup: Two computers, one running proftpd, one attempting to connect via filezilla. Both linux (xubuntu on the server, kubuntu on the client). Both are at the moment behind a router on a residential (read: dynamic IP) connection; the client is a laptop I plan to take away from the home network, so I'll need this to work externally. I have my router set up to allow specific ports forwarded to each machine and, where possible, have plugged in those numbers into proftpd (via gadmin, double-checking the config file) and filezilla. Attempting to connect via active mode using the internal IP works: Status: Connecting to 192.168.1.139:8085... Status: Connection established, waiting for welcome message... Response: 220 Crossroads FTP Command: USER <redacted> Response: 331 Password required for <redacted> Command: PASS ******* Response: 230 Anonymous access granted, restrictions apply Command: OPTS UTF8 ON Response: 200 UTF8 set to on Status: Connected Status: Retrieving directory listing... Command: PWD Response: 257 "/" is the current directory Command: TYPE I Response: 200 Type set to I Command: PORT 192,168,1,52,153,140 Response: 200 PORT command successful Command: LIST Response: 150 Opening ASCII mode data connection for file list Response: 226 Transfer complete Status: Directory listing successful Attempting to connect via the domain name, however, leads to issues; in active mode, the PORT is the last command to be received according to the server's logs, and in passive mode, it's the PASV command. This leads me to believe I'm being redirected to a bad port? Active Sample: Status: Resolving address of <url> Status: Connecting to <ip:port> Status: Connection established, waiting for welcome message... Response: 220 Crossroads FTP Command: USER <redacted> Response: 331 Password required for <redacted> Command: PASS ******* Response: 230 Anonymous access granted, restrictions apply Command: OPTS UTF8 ON Response: 200 UTF8 set to on Status: Connected Status: Retrieving directory listing... Command: PWD Response: 257 "/" is the current directory Command: TYPE I Response: 200 Type set to I Command: PORT 174,111,127,27,153,139 Response: 200 PORT command successful Command: LIST Error: Connection timed out Error: Failed to retrieve directory listing Passive sample: Status: Resolving address of ftp.bonsaiwebdesigns.com Status: Connecting to 174.111.127.27:8085... Status: Connection established, waiting for welcome message... Response: 220 Crossroads FTP Command: USER yamikuronue Response: 331 Password required for yamikuronue Command: PASS ******* Response: 230 Anonymous access granted, restrictions apply Command: OPTS UTF8 ON Response: 200 UTF8 set to on Status: Connected Status: Retrieving directory listing... Command: PWD Response: 257 "/" is the current directory Command: TYPE I Response: 200 Type set to I Command: PASV Response: 227 Entering Passive Mode (64,95,64,197,101,88). Command: LIST Error: Connection timed out Error: Failed to retrieve directory listing In both cases, the log file ends at "PORT" or "PASV" - there's no record of ever receiving a "LIST" command. Just above that I can see the attempt to connect actively via the internal IP, which does indeed include a LIST command. My config file includes "PassivePorts 20001-26999", which are the port forwards I set up for the ftp server, and "Port 8085", which is also forwarded to the same machine. I also have a MasqueradeAddress set up to prevent it from reporting its internal IP, which was an earlier issue I had. I think what I'm asking is, is there another setting someplace I have to change to get this setup to work?

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• Upgraded Ubuntu, all drives in one zpool marked unavailable

  - by Matt Sieker

  I just upgraded Ubuntu 14.04, and I had two ZFS pools on the server. There was some minor issue with me fighting with the ZFS driver and the kernel version, but that's worked out now. One pool came online, and mounted fine. The other didn't. The main difference between the tool is one was just a pool of disks (video/music storage), and the other was a raidz set (documents, etc) I've already attempted exporting and re-importing the pool, to no avail, attempting to import gets me this: root@kyou:/home/matt# zpool import -fFX -d /dev/disk/by-id/ pool: storage id: 15855792916570596778 state: UNAVAIL status: One or more devices contains corrupted data. action: The pool cannot be imported due to damaged devices or data. see: http://zfsonlinux.org/msg/ZFS-8000-5E config: storage UNAVAIL insufficient replicas raidz1-0 UNAVAIL insufficient replicas ata-SAMSUNG_HD103SJ_S246J90B134910 UNAVAIL ata-WDC_WD10EARS-00Y5B1_WD-WMAV51422523 UNAVAIL ata-WDC_WD10EARS-00Y5B1_WD-WMAV51535969 UNAVAIL The symlinks for those in /dev/disk/by-id also exist: root@kyou:/home/matt# ls -l /dev/disk/by-id/ata-SAMSUNG_HD103SJ_S246J90B134910* /dev/disk/by-id/ata-WDC_WD10EARS-00Y5B1_WD-WMAV51* lrwxrwxrwx 1 root root 9 May 27 19:31 /dev/disk/by-id/ata-SAMSUNG_HD103SJ_S246J90B134910 -> ../../sdb lrwxrwxrwx 1 root root 10 May 27 19:15 /dev/disk/by-id/ata-SAMSUNG_HD103SJ_S246J90B134910-part1 -> ../../sdb1 lrwxrwxrwx 1 root root 10 May 27 19:15 /dev/disk/by-id/ata-SAMSUNG_HD103SJ_S246J90B134910-part9 -> ../../sdb9 lrwxrwxrwx 1 root root 9 May 27 19:15 /dev/disk/by-id/ata-WDC_WD10EARS-00Y5B1_WD-WMAV51422523 -> ../../sdd lrwxrwxrwx 1 root root 10 May 27 19:15 /dev/disk/by-id/ata-WDC_WD10EARS-00Y5B1_WD-WMAV51422523-part1 -> ../../sdd1 lrwxrwxrwx 1 root root 10 May 27 19:15 /dev/disk/by-id/ata-WDC_WD10EARS-00Y5B1_WD-WMAV51422523-part9 -> ../../sdd9 lrwxrwxrwx 1 root root 9 May 27 19:15 /dev/disk/by-id/ata-WDC_WD10EARS-00Y5B1_WD-WMAV51535969 -> ../../sde lrwxrwxrwx 1 root root 10 May 27 19:15 /dev/disk/by-id/ata-WDC_WD10EARS-00Y5B1_WD-WMAV51535969-part1 -> ../../sde1 lrwxrwxrwx 1 root root 10 May 27 19:15 /dev/disk/by-id/ata-WDC_WD10EARS-00Y5B1_WD-WMAV51535969-part9 -> ../../sde9 Inspecting the various /dev/sd* devices listed, they appear to be the correct ones (The 3 1TB drives that were in a raidz array). I've run zdb -l on each drive, dumping it to a file, and running a diff. The only difference on the 3 are the guid fields (Which I assume is expected). All 3 labels on each one are basically identical, and are as follows: version: 5000 name: 'storage' state: 0 txg: 4 pool_guid: 15855792916570596778 hostname: 'kyou' top_guid: 1683909657511667860 guid: 8815283814047599968 vdev_children: 1 vdev_tree: type: 'raidz' id: 0 guid: 1683909657511667860 nparity: 1 metaslab_array: 33 metaslab_shift: 34 ashift: 9 asize: 3000569954304 is_log: 0 create_txg: 4 children[0]: type: 'disk' id: 0 guid: 8815283814047599968 path: '/dev/disk/by-id/ata-SAMSUNG_HD103SJ_S246J90B134910-part1' whole_disk: 1 create_txg: 4 children[1]: type: 'disk' id: 1 guid: 18036424618735999728 path: '/dev/disk/by-id/ata-WDC_WD10EARS-00Y5B1_WD-WMAV51422523-part1' whole_disk: 1 create_txg: 4 children[2]: type: 'disk' id: 2 guid: 10307555127976192266 path: '/dev/disk/by-id/ata-WDC_WD10EARS-00Y5B1_WD-WMAV51535969-part1' whole_disk: 1 create_txg: 4 features_for_read: Stupidly, I do not have a recent backup of this pool. However, the pool was fine before reboot, and Linux sees the disks fine (I have smartctl running now to double check) So, in summary: I upgraded Ubuntu, and lost access to one of my two zpools. The difference between the pools is the one that came up was JBOD, the other was zraid. All drives in the unmountable zpool are marked UNAVAIL, with no notes for corrupted data The pools were both created with disks referenced from /dev/disk/by-id/. Symlinks from /dev/disk/by-id to the various /dev/sd devices seems to be correct zdb can read the labels from the drives. Pool has already been attempted to be exported/imported, and isn't able to import again. Is there some sort of black magic I can invoke via zpool/zfs to bring these disks back into a reasonable array? Can I run zpool create zraid ... without losing my data? Is my data gone anyhow?

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• Server Admin is not allowing me to configure DNS

  - by Clinton Blackmore

  We have a Mac OS X 10.5.8 Server running DNS (and a few other services). When I connect to it (using Server Admin 10.5.3 [which comes from the Server Admin 10.5.7 tools]), and click to look at the DNS settings, all appears normal -- it shows many reverse entries and two top-level domains. However, when I select one of our domains and open the disclosure triangle, the list is empty! [There should be over a dozen entries, and the reverse entries do show up.] If I then tell it I want to add, say, an A Record to the domain, almost everything disappears -- and I am left with a list showing our two domains, one with a disclosure triangle underneath it showing a single entry, and one reverse entry to correspond to the new A record. named appears to be working fine. DNS names resolve. It appears to simply be that Server Admin is having problems with the data on the computer. No one here would have manually created a DNS entry. Now, while I think I've backed up the DNS (I backed up /var/named/, /etc/named.conf, and /etc/dns/, as mentioned here), I'm really not sure if just replacing the files would restore the DNS settings we have if things go south. I am contemplating going to settings and changing the log level from "Information" to "Debug", but 1) I am just a little concerned that it might write a bad configuration to the disk, and 2) I think it would only affect named and not Server Admin, and, so far as I can tell, named is not having a problem. (Nothing looks strange in /Library/Logs/named.log when I open it via Console/Terminal. Oddly, though, when I click on the 'log' button for DNS in Server Admin, I see no text at all, just a fully white window. When I look at one of our secondary DNS servers, I am able to see the log file through Server Admin.) This entry appears in the system log when I run Server Admin on the server: Jun 17 09:02:08 od1 Server Admin[3892]: Unexpected call to doMarkConfigurationAsDirty by 'DNS' plugin during updateConfigurationViewFromDescription It seems to occur after I've looked at DNS, look at another service, and then click back on DNS. Think that the most likely cause is a corrupt configuration file, I glanced through all the files that I backed up, and none of them is obviously gobbledygook. Here are some oddities I find when running Server Admin from a remote computer to manage the DNS. When I click to see the log file for DNS, the server starts writing messages like these to its system.log: Jun 17 09:59:04 od1 kernel[0]: Limiting open port RST response from 252 to 250 packets per second Jun 17 09:59:06 od1 kernel[0]: Limiting open port RST response from 258 to 250 packets per second This stops when I click on a different service. The inderterminate progress indicator (the spinning wheel that appears beside the "Revert" and "Save" buttons in the bottom-right corner of Server Admin) looks really strange. As far as I can tell, instead of just spinning and waiting, it is being told to start spinning repeatedly, resulting in a jerky animation. Here are some of the messages being logged on the computer running Server Admin: At startup: *** ERROR: -[GRAxes computeLayout]:1124 - plotRect height = 0.000000 <= 0.0 *** *** ERROR: -[GRChartView computeLayout]:1194 - Layout for overlay axes (0x18758f50) failed. *** (These messages don't concern me too much as they go away for a while if you delete ~/Library/Preferences/com.apple.ServerAdmin.plist). At shutdown: 2010-06-17 10:02:17.202 Server Admin[7770:10b] *** -[GroupTextField windowDidResignKey:]: unrecognized selector sent to instance 0x16e12490 More concerning are these messages: 2010-06-17 09:59:47.269 Server Admin[7770:10b] Unexpected call to doMarkConfigurationAsDirty by 'DNS' plugin during updateConfigurationViewFromDescription Server Admin(7770,0xb0453000) malloc: *** error for object 0x1c115390: double free *** set a breakpoint in malloc_error_break to debug 2010-06-17 10:01:00.795 Server Admin[7770:10b] *** -[ServiceEntry sessionHost]: unrecognized selector sent to instance 0x2af500 Any thoughts on: what the problem is how I can troubleshoot it or how to fix it? If I do need to wipe out DNS and restart, is there a good way to do this?

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• Install Intel USB 3.0 eXtensible Host Controller Driver for Windows Server 2008 R2 x64

  - by ffrugone

  According to Intel and Dell, by board is technically a 'desktop' board and they therefore do not support Intel USB 3.0 eXtensible Host Controller drivers for Windows Server 2008 (R2 x64). I'm trying to find a workaround. I found an entry on someone who tried to tackle this, but I can't make his fix work for me. Below, I have copied both his entry, and my reply. I'm a loyal stackoverflow user, and hopefully the people here at serverfault can help me: anyforumuser Re: GA-Z77X-UD5H USB3 Drivers not installing? « Reply #6 on: July 05, 2012, 04:12:59 am » Thanks to JoeMiner , his process for the network drivers gave me the clues to figure out to get the USB3 drivers working. I have got the intel USB3 drivers working at full speed in win server 2008r2 you have to edit the following file : 1. mup.xml in change the "Windows7" to "W2K8" 2. in setup.if2 under [groups] line starting with "HSCSDRIVER " change the "IsOS( ... )" entry to "IsOS(WIN2008_R2,WIN2008_R2_MAXSP)" inf files for all copy the content of the [Intel.NTAMD64.6.1] group to the [Intel.NTAMD64.6.2] group driver folders. here i am not entirely sure which is correct so there are some double up's. in the drivers folder copy the "Win7" folder to "win2008" , "win2008_r2" and "x64" ie your drivers folder should now contain the "win2008" , "win2008_r2" and "x64" folders and they contain contents of the win7 folder (the inf files should of already been fixed) Run install , It should install properly and work now. You will have to reboot If it doesn't work remove the intel usb3 controllers from device manager and get it to "scan for hardware changes" Good luck !!! benevida Re: GA-Z77X-UD5H Intel Network Drivers not installing? « Reply #7 on: August 13, 2012, 02:21:14 pm » Thank you anyforumuser! A process for getting this driver installed was exactly what I needed. However, I've hit a snag. I believe I've followed every step exactly as written, but I'm getting an error during installation. I get the message "One or more files that are required for installation are either missing or corrupted. Setup will exit." Behind the error, the 'Setup Progress' shows the current step as "Copying File: C:\Program Files (x86)\Intel\Intel(R) USB 3.0 eXtensible Host Controller Driver\Drivers\iusb3xhc.man". I've checked the installation files, and iusb3xhc.man seems to be a viable file in all of the Windows 2008 sub-directories of the Drivers folder. Therefore I don't see how the file could be missing and I doubt that it is corrupted, (although it does NOT exist in the \Drivers\HCSwitch folder). I opened 'Setup.if2', and there are two aspects to the step of copying iusb3xhc.man that caught my eye. First, the steps immediately preceding are set to 'error=ignore'. If they hadn't completed successfully, this is the first step where we'd hear about it. Second, this is the first step where the relative path '%source%\drivers\%_os%\%_ia%\' is used. If I haven't named the Windows 2008 sub-directories correctly, I could see where things are fouling up. In any event, if someone could take a look and make suggestions I'd appreciate it. Thank you.

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• How to recover data files from xampp-windows to xampp-linux after crash?

  - by David Buehler

  My Windows box died after I developed a database in xampp on it; fortunately I have a backup of the entire F:/TestWeb/Xampp partition. Unfortunately, I did not do an Export (nor dump) of the "Lws2" database before the crash. I have replaced the defunct machine with one running Mint7 (based on Ubuntu 9.04 "Jaunty Jackalope") and installed xampp-linux into the /opt partition, so the new xampp now runs fine in /opt/lampp, and says all the elements are secured by passwords (which I just assigned during this installation.) I assumed that Xamp-Windows installed in November would migrate easily to xampp-linux installed iin February -- a bad assumption. It apparently would have been simple if I had known enough to do an Export or a Dump before the crash, but.... The backup was done to a Network Attached Storage drive, which is formatted as "vfat" so the backup does not carry with it any valid ownership permissions from MySql on NTFS. I now see from my backup that the old data resided in \TestWeb\Xampp\Mysql\Data\Lws2\ and consists of 7 ".frm" files which define my tables. The actual data -- I suppose a ".sql" file or files -- has disappeared, and I am resigning myself to two days of retyping it. But I do not wish to do the table layouts all over again. So I copied Data tree to /opt/lampp/Data -- PhpMyAdmin does not see it. So I copied Lws2 tree to /opt/lampp/Lws2 -- PhpMyAdmin does not see it. So I copied Data tree to /opt/lampp/var/mysql/Data -- PhpMyAdmin does not see it. So I copied Lws2 tree to /opt/lampp/var/mysql/Lws2 -- PhpMyAdmin does not see it. So I adjusted all the permissions to stop saying owner "nobody" to owner "root" and gave full permissions to all groups and to all others, with permissions percolating down, in all 4 trees. You guessed it -- PhpMyAdmin does not see any database named Lws2, only its 4 default ones. I double-checked the permissions and rebooted Linux and repeated the tests. At some point in that process I did see PhpMyAdmin showing "lws2(7)" but when I clicked on it I saw a "no table found" message. I have not been able to recreate that experience. Apparently there are some setup files for MySql and for PhpMyAdmin which need to be set up by running a wizard or two or by editing the files directly. I grepped the TestWeb tree and found an old "ldir = "C:TestWeb\Xampp\MySql\" and a "DataDir = C:TestWeb\Xampp\MySql\" in a .php file and in a .bat file, but I cannot find the corresponding config file names on the /opt partition/ -- so it looks as if these wizards have not been run to create them. What config files files does Linux use to setup MySql config files for PhpMyAdmin? What wizards do I need to run to point the MySql engine and the PhpMyAdmin at the folder /opt/lampp/data/ with its lws2 folder inside it? Or which files do I need to edit, with a sample of what it normally says under Linux? Incidentally, I remember I converted from MyISAM with its .MYD and .MYI files to InnoDB after entering only a small amount of the data -- and I do not know what file types to look for -- perhaps my data is still there but under another guise or in another place? Is it something as simple as linux needing to see "/data/" instead of /Data? I will check that out while waiting for a response. If anyone can point me to documentation that discusses this level of detail -- I will read it avidly! In any case, thanks for any clarification you can give on this thorny problem. wizdum

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• MongoDB Crashed,Not able to start it again

  - by Kevin Parker

  Mongodb fail to start after showing this error...and not able to start it again..?Can u help me find out? *** glibc detected *** /usr/lib/mongodb/mongo: corrupted double-linked list: 0x000000000f750b50 *** Mon Nov 26 19:01:29 mongo got signal 11 (Segmentation fault), stack trace: ======= Backtrace: ========= /lib/x86_64-linux-gnu/libc.so.6(+0x788d6)[0x2b2db94198d6] /lib/x86_64-linux-gnu/libc.so.6(+0x7a841)[0x2b2db941b841] /lib/x86_64-linux-gnu/libc.so.6(cfree+0x73)[0x2b2db941f603] /usr/lib/mongodb/mongo(_ZN5boost6detail17sp_counted_impl_pIN5mongo7BSONObj6HolderEE7disposeEv+0x12)[0x45bd92] /usr/lib/mongodb/mongo(_ZN5boost6detail12shared_countD2Ev+0x49)[0x45d319] /lib/x86_64-linux-gnu/libc.so.6(exit+0xe1)[0x2b2db93da961] /usr/lib/mongodb/mongo(_Z10quitNicelyi+0x53)[0x458043] /lib/x86_64-linux-gnu/libpthread.so.0(+0xfc60)[0x2b2db753fc60] /lib/x86_64-linux-gnu/libc.so.6(kill+0x7)[0x2b2db93d4fe7] /lib/libreadline.so.6(+0x25888)[0x2b2db889b888] /lib/libreadline.so.6(rl_getc+0x5e)[0x2b2db889d9de] /lib/libreadline.so.6(rl_read_key+0xf8)[0x2b2db889e0c8] /lib/libreadline.so.6(readline_internal_char+0x61)[0x2b2db8889061] /lib/libreadline.so.6(readline+0x55)[0x2b2db88895b5] /usr/lib/mongodb/mongo(_Z13shellReadlinePKci+0x8a)[0x45694a] /usr/lib/mongodb/mongo(_Z5_mainiPPc+0x1506)[0x45a1a6] /usr/lib/mongodb/mongo(main+0x26)[0x45b1d6] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xff)[0x2b2db93bfeff] /usr/lib/mongodb/mongo[0x456449] ======= Memory map: ======== 00400000-0055c000 r-xp 00000000 fd:03 32385496 /usr/lib/mongodb/mongo 0075c000-00762000 r--p 0015c000 fd:03 32385496 /usr/lib/mongodb/mongo 00762000-00765000 rw-p 00162000 fd:03 32385496 /usr/lib/mongodb/mongo 00765000-00767000 rw-p 00765000 00:00 0 0f74e000-0f961000 rw-p 0f74e000 00:00 0 [heap] 2b2db730d000-2b2db732e000 r-xp 00000000 fd:03 32112840 /lib/x86_64-linux-gnu/ld-2.13.so 2b2db732e000-2b2db7331000 rw-p 2b2db732e000 00:00 0 2b2db7331000-2b2db7351000 rwxp 2b2db7331000 00:00 0 2b2db752d000-2b2db752e000 r--p 00020000 fd:03 32112840 /lib/x86_64-linux-gnu/ld-2.13.so 2b2db752e000-2b2db7530000 rw-p 00021000 fd:03 32112840 /lib/x86_64-linux-gnu/ld-2.13.so 2b2db7530000-2b2db7548000 r-xp 00000000 fd:03 32112843 /lib/x86_64-linux-gnu/libpthread-2.13.so 2b2db7548000-2b2db7748000 ---p 00018000 fd:03 32112843 /lib/x86_64-linux-gnu/libpthread-2.13.so 2b2db7748000-2b2db7749000 r--p 00018000 fd:03 32112843 /lib/x86_64-linux-gnu/libpthread-2.13.so 2b2db7749000-2b2db774a000 rw-p 00019000 fd:03 32112843 /lib/x86_64-linux-gnu/libpthread-2.13.so 2b2db774a000-2b2db774e000 rw-p 2b2db774a000 00:00 0 2b2db774e000-2b2db7836000 r-xp 00000000 fd:03 32380634 /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.14 2b2db7836000-2b2db7a35000 ---p 000e8000 fd:03 32380634 /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.14 2b2db7a35000-2b2db7a3d000 r--p 000e7000 fd:03 32380634 /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.14 2b2db7a3d000-2b2db7a3f000 rw-p 000ef000 fd:03 32380634 /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.14 2b2db7a3f000-2b2db7a55000 rw-p 2b2db7a3f000 00:00 0 2b2db7a55000-2b2db7a58000 r-xp 00000000 fd:03 32244866 /usr/lib/libboost_system.so.1.42.0 2b2db7a58000-2b2db7c57000 ---p 00003000 fd:03 32244866 /usr/lib/libboost_system.so.1.42.0 2b2db7c57000-2b2db7c58000 r--p 00002000 fd:03 32244866 /usr/lib/libboost_system.so.1.42.0 2b2db7c58000-2b2db7c59000 rw-p 00003000 fd:03 32244866 /usr/lib/libboost_system.so.1.42.0 2b2db7c59000-2b2db7c6d000 r-xp 00000000 fd:03 32244882 /usr/lib/libboost_thread.so.1.42.0 2b2db7c6d000-2b2db7e6c000 ---p 00014000 fd:03 32244882 /usr/lib/libboost_thread.so.1.42.0 2b2db7e6c000-2b2db7e6e000 r--p 00013000 fd:03 32244882 /usr/lib/libboost_thread.so.1.42.0 2b2db7e6e000-2b2db7e6f000 rw-p 00015000 fd:03 32244882 /usr/lib/libboost_thread.so.1.42.0 2b2db7e6f000-2b2db7e83000 r-xp 00000000 fd:03 32244880 /usr/lib/libboost_filesystem.so.1.42.0 2b2db7e83000-2b2db8082000 ---p 00014000 fd:03 32244880 Mon Nov 26 19:01:29 mongo got signal 6 (Aborted), stack trace: Mon Nov 26 19:01:29 0x45e03f 0x457694 0x2b2db93d4d80 0x2b2db93d4d05 0x2b2db93d8ab6 0x2b2db940fa9b 0x2b2db94198d6 0x2b2db941b841 0x2b2db941f603 0x45bd92 0x45d319 0x2b2db93da961 0x458043 0x2b2db753fc60 0x2b2db93d4fe7 0x2b2db889b888 0x2b2db889d9de 0x2b2db889e0c8 0x2b2db8889061 0x2b2db88895b5 /usr/lib/mongodb/mongo(_ZN5mongo15printStackTraceERSo+0x1f) [0x45e03f] /usr/lib/mongodb/mongo(_Z12quitAbruptlyi+0x324) [0x457694] /lib/x86_64-linux-gnu/libc.so.6(+0x33d80) [0x2b2db93d4d80] /lib/x86_64-linux-gnu/libc.so.6(gsignal+0x35) [0x2b2db93d4d05] /lib/x86_64-linux-gnu/libc.so.6(abort+0x186) [0x2b2db93d8ab6] /lib/x86_64-linux-gnu/libc.so.6(+0x6ea9b) [0x2b2db940fa9b] /lib/x86_64-linux-gnu/libc.so.6(+0x788d6) [0x2b2db94198d6] /lib/x86_64-linux-gnu/libc.so.6(+0x7a841) [0x2b2db941b841] /lib/x86_64-linux-gnu/libc.so.6(cfree+0x73) [0x2b2db941f603] /usr/lib/mongodb/mongo(_ZN5boost6detail17sp_counted_impl_pIN5mongo7BSONObj6HolderEE7disposeEv+0x12) [0x45bd92] /usr/lib/mongodb/mongo(_ZN5boost6detail12shared_countD2Ev+0x49) [0x45d319] /lib/x86_64-linux-gnu/libc.so.6(exit+0xe1) [0x2b2db93da961] /usr/lib/mongodb/mongo(_Z10quitNicelyi+0x53) [0x458043] /lib/x86_64-linux-gnu/libpthread.so.0(+0xfc60) [0x2b2db753fc60] /lib/x86_64-linux-gnu/libc.so.6(kill+0x7) [0x2b2db93d4fe7] /lib/libreadline.so.6(+0x25888) [0x2b2db889b888] /lib/libreadline.so.6(rl_getc+0x5e) [0x2b2db889d9de] /lib/libreadline.so.6(rl_read_key+0xf8) [0x2b2db889e0c8] /lib/libreadline.so.6(readline_internal_char+0x61) [0x2b2db8889061] /lib/libreadline.so.6(readline+0x55) [0x2b2db88895b5] Any One have any idea?Why MongoDb Crashed? OS:ubuntu 11.04 2.6.32-pony6-3 RAM:2 GB

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• Multiple data centers and HTTP traffic: DNS Round Robin is the ONLY way to assure instant fail-over?

  - by vmiazzo

  Hi, Multiple A records pointing to the same domain seem to be used almost exclusively to implement DNS Round Robin as a cheap load balancing technique. The usual warning against DNS RR is that it is not good for high availability. When 1 IP goes down clients will continue to use it for minutes. A load balancer is often suggested as a better choice. Both claims are not completely true: When the traffic is HTTP then, most of the HTML browsers are able to automatically try the next A record if the previous is down, without a new DNS look-up. Read here chapter 3.1 and here. When multiple data centers are involved then, DNS RR is the only option to distribute traffic across them. So, is it true that, with multiple data centers and HTTP traffic, the use of DNS RR is the ONLY way to assure instant fail-over when one data center goes down? Thanks, Valentino Edit: Off course each data center has a local Load Balancer with hot spare. It's OK to sacrifice session affinity for an instant fail-over. AFAIK the only way for a DNS to suggest a data center instead of another is to reply with just the IP (or IPs) associated to that data center. If the data center becomes unreachable then all those IP are also unreachables. This means that, even if smart HTML browsers are able to instantly try another A record , all the attempts will fail until the local cache entry expires and a new DNS lookup is done, fetching the new working IPs (I assume DNS automatically suggests to a new data center when one fail). So, "smart DNS" cannot assure instant fail-over. Conversely a DNS round-robin permits it. When one data center fail, the smart HTML browsers (most of them) instantly try the other cached A records jumping to another (working) data center. So, DNS round-robin doesn't assure session affinity or the lowest RTT but seems to be the only way to assure instant fail-over when the clients are "smart" HTML browsers. Edit 2: Some people suggest TCP Anycast as a definitive solution. In this paper (chapter 6) is explained that Anycast fail-over is related to BGP convergence. For this reason Anycast can employ from 15 minutes to 20 seconds to complete. 20 seconds are possible on networks where the topology was optimized for this. Probably just CDN operators can grant such fast fail-overs. Edit 3:* I did some DNS look-ups and traceroutes (maybe some expert can double check) and: The only CDN using TCP Anycast seems to be CacheFly, other operators like CDN networks and BitGravity use CacheFly. Seems that their edges cannot be used as reverse proxies. Therefore, they cannot be used to grant instant failover. Akamai and LimeLight seems to use geo-aware DNS. But! They return multiple A records. From traceroutes seems that the returned IPs are on the same data center. So, I'm puzzled on how they can offer a 100% SLA when one data center goes down.

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