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• JavaOne User Group Sunday

  - by Tori Wieldt

  Before any "official" sessions of JavaOne 2012, the Java community was already sizzling. User Group Sunday was a great success, with several sessions offered by Java community members for anyone wanting to attend. Sessions were both about Java and best practices for running a JUG. Technical sessions included "Autoscaling Web Java Applications: Handle Peak Traffic with Zero Downtime and Minimized Cost,"  "Using Java with HTML5 and CSS3," and "Gooey and Sticky Bits: Everything You Ever Wanted to Know About Java." Several sessions were about how to start and run a JUG, like "Getting Speakers, Finding Sponsors, Planning Events: A Day in the Life of a JUG" and "JCP and OpenJDK: Using the JUGs’ “Adopt” Programs in Your Group." Badr ElHouari and Faiçal Boutaounte presented the session "Why Communities Are Important and How to Start One." They used the example of the Morocco JUG, which they started. Before the JUG, there was no "Java community," they explained. They shared their best practices, including: have fun, enjoy what you are doing get a free venue to have regular meetings, a University is a good choice run a conference, it gives you visibility and brings in new members students are a great way to grow a JUG Badr was proud to mention JMaghreb, a first-time conference that the Morocco JUG is hosting in November. They have secured sponsors and international speakers, and are able to offer a free conference for Java developers in North Africa. The session also included a free-flowing discussion about recruiters (OK to come to meetings, but not to dominate them), giving out email addresses (NEVER do without permission), no-show rates (50% for free events) and the importance of good content (good speakers really help!). Trisha Gee, member of the London Java Community (LJC) was one of the presenters for the session "Benefits of Open Source." She explained how open sourcing the LMAX Disruptor (a high performance inter-thread messaging library) gave her company LMAX several benefits, including more users, more really good quality new hires, and more access to 3rd party companies. Being open source raised the visibility of the company and the product, which was good in many ways. "We hired six really good coders in three months," Gee said. They also got community contributors for their code and more cred with technologists. "We had been unsuccessful at getting access to executives from other companies in the high-performance space. But once we were open source, the techies at the company had heard of us, knew our code was good, and that opened lots of doors for us." So, instead of "giving away the secret sauce," by going open source, LMAX gained many benefits. "It was a great day," said Bruno Souza, AKA The Brazilian Java Man, "the sessions were well attended and there was lots of good interaction." Sizzle and steak!

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• Why Is Hibernation Still Used?

  - by Jason Fitzpatrick

  With the increased prevalence of fast solid-state hard drives, why do we still have system hibernation? Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites. The Question SuperUser reader Moses wants to know why he should use hibernate on a desktop machine: I’ve never quite understood the original purpose of the Hibernation power state in Windows. I understand how it works, what processes take place, and what happens when you boot back up from Hibernate, but I’ve never truly understood why it’s used. With today’s technology, most notably with SSDs, RAM and CPUs becoming faster and faster, a cold boot on a clean/efficient Windows installation can be pretty fast (for some people, mere seconds from pushing the power button). Standby is even faster, sometimes instantaneous. Even SATA drives from 5-6 years ago can accomplish these fast boot times. Hibernation seems pointless to me [on desktop computers] when modern technology is considered, but perhaps there are applications that I’m not considering. What was the original purpose behind hibernation, and why do people still use it? Quite a few people use hibernate, so what is Moses missing in the big picture? The Answer SuperUser contributor Vignesh4304 writes: Normally hibernate mode saves your computer’s memory, this includes for example open documents and running applications, to your hard disk and shuts down the computer, it uses zero power. Once the computer is powered back on, it will resume everything where you left off. You can use this mode if you won’t be using the laptop/desktop for an extended period of time, and you don’t want to close your documents. Simple Usage And Purpose: Save electric power and resuming of documents. In simple terms this comment serves nice e.g (i.e. you will sleep but your memories are still present). Why it’s used: Let me describe one sample scenario. Imagine your battery is low on power in your laptop, and you are working on important projects on your machine. You can switch to hibernate mode – it will result your documents being saved, and when you power on, the actual state of application gets restored. Its main usage is like an emergency shutdown with an auto-resume of your documents. MagicAndre1981 highlights the reason we use hibernate everyday: Because it saves the status of all running programs. I leave all my programs open and can resume working the next day very easily. Doing a real boot would require to start all programs again, load all the same files into those programs, get to the same place that I was at before, and put all my windows in exactly the same place. Hibernating saves a lot of work pulling these things back up again. It’s not unusual to find computers around the office here that have been hibernated day in and day out for months without an actual full system shutdown and restart. It’s enormously convenient to freeze your work space at the exact moment you stopped working and to turn right around and resume there the next morning. Have something to add to the explanation? Sound off in the the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.     

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• Cloud hosted CI for .NET projects

  - by Scott Dorman

  Originally posted on: http://geekswithblogs.net/sdorman/archive/2014/06/02/cloud-hosted-ci-for-.net-projects.aspxContinuous integration (CI) is important. If you don’t have it set up…you should. There are a lot of different options available for hosting your own CI server, but they all require you to maintain your own infrastructure. If you’re a business, that generally isn’t a problem. However, if you have some open source projects hosted, for example on GitHub, there haven’t really been any options. That has changed with the latest release of AppVeyor, which bills itself as “Continuous integration for busy developers.” What’s different about AppVeyor is that it’s a hosted solution. Why is that important? By being a hosted solution, it means that I don’t have to maintain my own infrastructure for a build server. How does that help if you’re hosting an open source project? AppVeyor has a really competitive pricing plan. For an unlimited amount of public repositories, it’s free. That gives you a cloud hosted CI system for all of your GitHub projects for the cost of some time to set them up, which actually isn’t hard to do at all. I have several open source projects (hosted at https://github.com/scottdorman), so I signed up using my GitHub credentials. AppVeyor fully supported my two-factor authentication with GitHub, so I never once had to enter my password for GitHub into AppVeyor. Once it was done, I authorized GitHub and it instantly found all of the repositories I have (both the ones I created and the ones I cloned from elsewhere). You can even add “build badges” to your markdown files in GitHub, so anyone who visits your project can see the status of the lasted build. Out of the box, you can simply select a repository, add the build project, click New Build and wait for the build to complete. You now have a complete CI server running for your project. The best part of this, besides the fact that it “just worked” with almost zero configuration is that you can configure it through a web-based interface which is very streamlined, clean and easy to use or you can use a appveyor.yml file. This means that you can define your CI build process (including any scripts that might need to be run, etc.) in a standard file format (the YAML format) and store it in your repository. The benefits to that are huge. The file becomes a versioned artifact in your source control system, so it can be branched, merged, and is completely transparent to anyone working on the project. By the way, AppVeyor isn’t limited to just GitHub. It currently supports GitHub, BitBucket, Visual Studio Online, and Kiln. I did have a few issues getting one of my projects to build, but the same day I posted the problem to the support forum a fix was deployed, and I had a functioning CI build about 5 minutes after that. Since then, I’ve provided some additional feature requests and had a few other questions, all of which have seen responses within a 24-hour period. I have to say that it’s easily been one of the best customer support experiences I’ve seen in a long time. AppVeyor is still young, so it doesn’t yet have full feature parity with some of the older (more established) CI systems available,  but it’s getting better all the time and I have no doubt that it will quickly catch up to those other CI systems and then pass them. The bottom line, if you’re looking for a good cloud-hosted CI system for your .NET-based projects, look at AppVeyor.

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• Oracle GoldenGate 11g Release 2 Launch Webcast Replay Available

  - by Irem Radzik

  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:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif"; mso-fareast-font-family:"Times New Roman";} For those of you who missed Oracle GoldenGate 11g Release 2 launch webcasts last week, the replay is now available from the following url. Harnessing the Power of the New Release of Oracle GoldenGate 11g I would highly recommend watching the webcast to meet many new features of the new release and hear the product management team respond to the questions from the audience in a nice long Q&A section. In my blog last week I listed the media coverage for this new release. There is a new article published by ITJungle talking about Oracle GoldenGate’s heterogeneity and support for DB2 for iSeries: Oracle Completes DB2/400 Support in Data Replication Tool As mentioned in last week’s blog, we received over 150 questions from the audience and in this blog I'd like to continue to post some of the frequently asked,  questions and their answers: Question: What are the fundamental differences between classic data capture and integrated data capture? Do both use the redo logs in the source database? Answer: Yes, they both use redo logs. Classic capture parses the redo log data directly, whereas the Integrated Capture lets the Oracle database parse the redo log record using an internal API. Question: Does GoldenGate version need to match Oracle Database version? Answer: No, they are not directly linked. Oracle GoldenGate 11g Release 2 supports Oracle Database version 10gR2 as well. For Oracle Database version 10gR1 and Oracle Database version 9i you will need GoldenGate11g Release 1 or lower. And for Oracle Database 8i you need Oracle GoldenGate 10 or earlier versions. Question: If I already use Data Guard, do I need GoldenGate? Answer: Data Guard is designed as the best disaster recovery solution for Oracle Database. If you would like to implement a bidirectional Active-Active replication solution or need to move data between heterogeneous systems, you will need GoldenGate. Question: On Compression and GoldenGate, if the source uses compression, is it required that the target also use compression? Answer: No, the source and target do not need to have the same compression settings. Question: Does GG support Advance Security Option on the Source database? Answer: Yes it does. Question: Can I use GoldenGate to upgrade the Oracle Database to 11g and do OS migration at the same time? Answer: Yes, this is a very common project where GoldenGate can eliminate downtime, give flexibility to test the target as needed, and minimize risks with fail-back option to the old environment. For more information on database upgrades please check out the following white papers: Best Practices for Migrating/Upgrading Oracle Database Using Oracle GoldenGate 11g Zero-Downtime Database Upgrades Using Oracle GoldenGate Question: Does GoldenGate create any trigger in the source database table level or row level to for real-time data integration? Answer: No, GoldenGate does not create triggers. Question: Can transformation be done after insert to destination table or need to be done before? Answer: It can happen in the Capture (Extract) process, in the  Delivery (Replicat) process, or in the target database. For more resources on Oracle GoldenGate 11gR2 please check out our Oracle GoldenGate 11gR2 resource kit as well.

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• Observing flow control idle time in TCP

  - by user12820842

  Previously I described how to observe congestion control strategies during transmission, and here I talked about TCP's sliding window approach for handling flow control on the receive side. A neat trick would now be to put the pieces together and ask the following question - how often is TCP transmission blocked by congestion control (send-side flow control) versus a zero-sized send window (which is the receiver saying it cannot process any more data)? So in effect we are asking whether the size of the receive window of the peer or the congestion control strategy may be sub-optimal. The result of such a problem would be that we have TCP data that we could be transmitting but we are not, potentially effecting throughput. So flow control is in effect: when the congestion window is less than or equal to the amount of bytes outstanding on the connection. We can derive this from args[3]-tcps_snxt - args[3]-tcps_suna, i.e. the difference between the next sequence number to send and the lowest unacknowledged sequence number; and when the window in the TCP segment received is advertised as 0 We time from these events until we send new data (i.e. args[4]-tcp_seq = snxt value when window closes. Here's the script: #!/usr/sbin/dtrace -s #pragma D option quiet tcp:::send / (args[3]-tcps_snxt - args[3]-tcps_suna) = args[3]-tcps_cwnd / { cwndclosed[args[1]-cs_cid] = timestamp; cwndsnxt[args[1]-cs_cid] = args[3]-tcps_snxt; @numclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = count(); } tcp:::send / cwndclosed[args[1]-cs_cid] && args[4]-tcp_seq = cwndsnxt[args[1]-cs_cid] / { @meantimeclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = avg(timestamp - cwndclosed[args[1]-cs_cid]); @stddevtimeclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = stddev(timestamp - cwndclosed[args[1]-cs_cid]); @numclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = count(); cwndclosed[args[1]-cs_cid] = 0; cwndsnxt[args[1]-cs_cid] = 0; } tcp:::receive / args[4]-tcp_window == 0 && (args[4]-tcp_flags & (TH_SYN|TH_RST|TH_FIN)) == 0 / { swndclosed[args[1]-cs_cid] = timestamp; swndsnxt[args[1]-cs_cid] = args[3]-tcps_snxt; @numclosed["swnd", args[2]-ip_saddr, args[4]-tcp_dport] = count(); } tcp:::send / swndclosed[args[1]-cs_cid] && args[4]-tcp_seq = swndsnxt[args[1]-cs_cid] / { @meantimeclosed["swnd", args[2]-ip_daddr, args[4]-tcp_sport] = avg(timestamp - swndclosed[args[1]-cs_cid]); @stddevtimeclosed["swnd", args[2]-ip_daddr, args[4]-tcp_sport] = stddev(timestamp - swndclosed[args[1]-cs_cid]); swndclosed[args[1]-cs_cid] = 0; swndsnxt[args[1]-cs_cid] = 0; } END { printf("%-6s %-20s %-8s %-25s %-8s %-8s\n", "Window", "Remote host", "Port", "TCP Avg WndClosed(ns)", "StdDev", "Num"); printa("%-6s %-20s %-8d %@-25d %@-8d %@-8d\n", @meantimeclosed, @stddevtimeclosed, @numclosed); } So this script will show us whether the peer's receive window size is preventing flow ("swnd" events) or whether congestion control is limiting flow ("cwnd" events). As an example I traced on a server with a large file transfer in progress via a webserver and with an active ssh connection running "find / -depth -print". Here is the output: ^C Window Remote host Port TCP Avg WndClosed(ns) StdDev Num cwnd 10.175.96.92 80 86064329 77311705 125 cwnd 10.175.96.92 22 122068522 151039669 81 So we see in this case, the congestion window closes 125 times for port 80 connections and 81 times for ssh. The average time the window is closed is 0.086sec for port 80 and 0.12sec for port 22. So if you wish to change congestion control algorithm in Oracle Solaris 11, a useful step may be to see if congestion really is an issue on your network. Scripts like the one posted above can help assess this, but it's worth reiterating that if congestion control is occuring, that's not necessarily a problem that needs fixing. Recall that congestion control is about controlling flow to prevent large-scale drops, so looking at congestion events in isolation doesn't tell us the whole story. For example, are we seeing more congestion events with one control algorithm, but more drops/retransmission with another? As always, it's best to start with measures of throughput and latency before arriving at a specific hypothesis such as "my congestion control algorithm is sub-optimal".

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• The Future of Air Travel: Intelligence and Automation

  - by BobEvans

  Remember those white-knuckle flights through stormy weather where unexpected plunges in altitude result in near-permanent relocations of major internal organs? Perhaps there’s a better way, according to a recent Wall Street Journal article: “Pilots of a Honeywell International Inc. test plane stayed on their initial flight path, relying on the company's latest onboard radar technology to steer through the worst of the weather. The specially outfitted Boeing 757 barely shuddered as it gingerly skirted some of the most ferocious storm cells over Fort Walton Beach and then climbed above the rest in zero visibility.” Or how about the multifaceted check-in process, which might not wreak havoc on liver location but nevertheless makes you wonder if you’ve been trapped in some sort of covert psychological-stress test? Another WSJ article, called “The Self-Service Airport,” says there’s reason for hope there as well: “Airlines are laying the groundwork for the next big step in the airport experience: a trip from the curb to the plane without interacting with a single airline employee. At the airport of the near future, ‘your first interaction could be with a flight attendant,’ said Ben Minicucci, chief operating officer of Alaska Airlines, a unit of Alaska Air Group Inc.” And in the topsy-turvy world of air travel, it’s not just the passengers who’ve been experiencing bumpy rides: the airlines themselves are grappling with a range of challenges—some beyond their control, some not—that make profitability increasingly elusive in spite of heavy demand for their services. A recent piece in The Economist illustrates one of the mega-challenges confronting the airline industry via a striking set of contrasting and very large numbers: while the airlines pay $7 billion per year to third-party computerized reservation services, the airlines themselves earn a collective profit of only $3 billion per year. In that context, the anecdotes above point unmistakably to the future that airlines must pursue if they hope to be able to manage some of the factors outside of their control (e.g., weather) as well as all of those within their control (operating expenses, end-to-end visibility, safety, load optimization, etc.): more intelligence, more automation, more interconnectedness, and more real-time awareness of every facet of their operations. Those moves will benefit both passengers and the air carriers, says the WSJ piece on The Self-Service Airport: “Airlines say the advanced technology will quicken the airport experience for seasoned travelers—shaving a minute or two from the checked-baggage process alone—while freeing airline employees to focus on fliers with questions. ‘It's more about throughput with the resources you have than getting rid of humans,’ said Andrew O'Connor, director of airport solutions at Geneva-based airline IT provider SITA.” Oracle’s attempting to help airlines gain control over these challenges by blending together a range of its technologies into a solution called the Oracle Airline Data Model, which suggests the following steps: • To retain and grow their customer base, airlines need to focus on the customer experience. • To personalize and differentiate the customer experience, airlines need to effectively manage their passenger data. • The Oracle Airline Data Model can help airlines jump-start their customer-experience initiatives by consolidating passenger data into a customer data hub that drives realtime business intelligence and strategic customer insight. • Oracle’s Airline Data Model brings together multiple types of data that can jumpstart your data-warehousing project with rich out-of-the-box functionality. • Oracle’s Intelligent Warehouse for Airlines brings together the powerful capabilities of Oracle Exadata and the Oracle Airline Data Model to give you real-time strategic insights into passenger demand, revenues, sales channels and your flight network. The airline industry aside, the bullet points above offer a broad strategic outline for just about any industry because the customer experience is becoming pre-eminent in each and there is simply no way to deliver world-class customer experiences unless a company can capture, manage, and analyze all of the relevant data in real-time. I’ll leave you with two thoughts from the WSJ article about the new in-flight radar system from Honeywell: first, studies show that a single episode of serious turbulence can wrack up $150,000 in additional costs for an airline—so, it certainly behooves the carriers to gain the intelligence to avoid turbulence as much as possible. And second, it’s back to that top-priority customer-experience thing and the value that ever-increasing levels of intelligence can deliver. As the article says: “In the cabin, reporters watched screens showing the most intense parts of the nearly 10-mile wide storm, which churned some 7,000 feet below, in vibrant red and other colors. The screens also were filled with tiny symbols depicting likely locations of lightning and hail, which can damage planes and wreak havoc on the nerves of white-knuckle flyers.”  (Bob Evans is senior vice-president, communications, for Oracle.)  

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• How do you update live web sites with code changes?

  - by Aaron Anodide

  I know this is a very basic question. If someone could humor me and tell me how they would handle this, I'd be greatful. I decided to post this because I am about to install SynchToy to remedy the issue below, and I feel a bit unprofessional using a "Toy" but I can't think of a better way. Many times I find when I am in this situation, I am missing some painfully obvious way to do things - this comes from being the only developer in the company. ASP.NET web application developed on my computer at work Solution has 2 projects: Website (files) WebsiteLib (C#/dll) Using a Git repository Deployed on a GoGrid 2008R2 web server Deployment: Make code changes. Push to Git. Remote desktop to server. Pull from Git. Overwrite the live files by dragging/dropping with windows explorer. In Step 5 I delete all the files from the website root.. this can't be a good thing to do. That's why I am about to install SynchToy... UPDATE: THANKS for all the useful responses. I can't pick which one to mark answer - between using a web deployment - it looks like I have several useful suggesitons: Web Project = whole site packaged into a single DLL - downside for me I can't push simple updates - being a lone developer in a company of 50, this remains something that is simpler at times. Pulling straight from SCM into web root of site - i originally didn't do this out of fear that my SCM hidden directory might end up being exposed, but the answers here helped me get over that (although i still don't like having one more thing to worry about forgetting to make sure is still true over time) Using a web farm, and systematically deploying to nodes - this is the ideal solution for zero downtime, which is actually something I care about since the site is essentially a real time revenue source for my company - i might have a hard time convincing them to double the cost of the servers though. -- finally, the re-enforcement of the basic principal that there needs to be a single click deployment for the site OR ELSE THERE SOMETHING WRONG is probably the most useful thing I got out of the answers. UPDATE 2: I thought I come back to this and update with the actual solution that's been in place for many months now and is working perfectly (for my single web server solution). The process I use is: Make code changes Push to Git Remote desktop to server Pull from Git Run the following batch script: cd C:\Users\Administrator %systemroot%\system32\inetsrv\appcmd.exe stop site "/site.name:Default Web Site" robocopy Documents\code\da\1\work\Tree\LendingTreeWebSite1 c:\inetpub\wwwroot /E /XF connectionsconfig Web.config %systemroot%\system32\inetsrv\appcmd.exe start site "/site.name:Default Web Site" As you can see this brings the site down, uses robocopy to intelligently copy the files that have changed then brings the site back up. It typically runs in less than 2 seconds. Since peak traffic on this site is about 2 requests per second, missing 4 requests per site update is acceptable. Sine I've gotten more proficient with Git I've found that the first four steps above being a "manual process" is also acceptable, although I'm sure I could roll the whole thing into a single click if I wanted to. The documentation for AppCmd.exe is here. The documentation for Robocopy is here.

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• Essbase BSO Data Fragmentation

  - by Ann Donahue

  Essbase BSO Data Fragmentation Data fragmentation naturally occurs in Essbase Block Storage (BSO) databases where there are a lot of end user data updates, incremental data loads, many lock and send, and/or many calculations executed.  If an Essbase database starts to experience performance slow-downs, this is an indication that there may be too much fragmentation.  See Chapter 54 Improving Essbase Performance in the Essbase DBA Guide for more details on measuring and eliminating fragmentation: http://docs.oracle.com/cd/E17236_01/epm.1112/esb_dbag/daprcset.html Fragmentation is likely to occur in the following situations: Read/write databases that users are constantly updating data Databases that execute calculations around the clock Databases that frequently update and recalculate dense members Data loads that are poorly designed Databases that contain a significant number of Dynamic Calc and Store members Databases that use an isolation level of uncommitted access with commit block set to zero There are two types of data block fragmentation Free space tracking, which is measured using the Average Fragmentation Quotient statistic. Block order on disk, which is measured using the Average Cluster Ratio statistic. Average Fragmentation Quotient The Average Fragmentation Quotient ratio measures free space in a given database.  As you update and calculate data, empty spaces occur when a block can no longer fit in its original space and will either append at the end of the file or fit in another empty space that is large enough.  These empty spaces take up space in the .PAG files.  The higher the number the more empty spaces you have, therefore, the bigger the .PAG file and the longer it takes to traverse through the .PAG file to get to a particular record.  An Average Fragmentation Quotient value of 3.174765 means the database is 3% fragmented with free space. Average Cluster Ratio Average Cluster Ratio describes the order the blocks actually exist in the database. An Average Cluster Ratio number of 1 means all the blocks are ordered in the correct sequence in the order of the Outline.  As you load data and calculate data blocks, the sequence can start to be out of order.  This is because when you write to a block it may not be able to place back in the exact same spot in the database that it existed before.  The lower this number the more out of order it becomes and the more it affects performance.  An Average Cluster Ratio value of 1 means no fragmentation.  Any value lower than 1 i.e. 0.01032828 means the data blocks are getting further out of order from the outline order. Eliminating Data Block Fragmentation Both types of data block fragmentation can be removed by doing a dense restructure or export/clear/import of the data.  There are two types of dense restructure: 1. Implicit Restructures Implicit dense restructure happens when outline changes are done using EAS Outline Editor or Dimension Build. Essbase restructures create new .PAG files restructuring the data blocks in the .PAG files. When Essbase restructures the data blocks, it regenerates the index automatically so that index entries point to the new data blocks. Empty blocks are NOT removed with implicit restructures. 2. Explicit Restructures Explicit dense restructure happens when a manual initiation of the database restructure is executed. An explicit dense restructure is a full restructure which comprises of a dense restructure as outlined above plus the removal of empty blocks Empty Blocks vs. Fragmentation The existence of empty blocks is not considered fragmentation.  Empty blocks can be created through calc scripts or formulas.  An empty block will add to an existing database block count and will be included in the block counts of the database properties.  There are no statistics for empty blocks.  The only way to determine if empty blocks exist in an Essbase database is to record your current block count, export the entire database, clear the database then import the exported data.  If the block count decreased, the difference is the number of empty blocks that had existed in the database.

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• Best approach to depth streaming via existing codec

  - by Kevin

  I'm working on a development system (and game) intended for games set mostly in static third-person views. We produce our scenery by CG and photographic techniques. Our background art is rendered off-line by a production-grade renderer. To allow the runtime imagery to properly interact with the background art, I wrote a program to convert from depth output by Mental Ray into a texture, and a pixel shader to draw a quad such that the Z data comes from the texture. This technique is working out very well, but now we've decided that some of the camera angle changes between scenes should be animated. The animation itself is straightforward to produce from our CG models. We intend to encode it to some HD video codec such as H.264. The problem is that in order to maintain our runtime imagery on the screen, the depth buffer will need to be loaded for each video frame. Due to the bandwidth, the video's depth data will need to be compressed efficiently. I've looked into methods for performing temporal compression of depth info and found an interesting research paper here: http://web4.cs.ucl.ac.uk/staff/j.kautz/publications/depth-streaming.pdf The method establishes a mapping between 16-bit depth values and YCbCr values. The mapping is tuned to the properties of existing video codecs in order to maximize precision of the decoded depths after the YCbCr has undergone video compression. It allows an existing, unmodified video codec to be used on the backend. I'm looking at how to pull this off with the least possible work. (This design change was unplanned.) Our game engine itself is native C++, presently for Win32 and DirectX, although we've worked hard to keep platform dependence segregated because we intend other ports. We don't have motion video facilities in the engine yet but will ultimately need that anyway for cinematics. I was planning on using some off-the-shelf motion video solution we can plug into our engine, and haven't chosen one yet. This new added requirement makes selecting one harder since, among other things, we'll now need to bypass colourspace conversion on one of the streams, and also will need to be playing two streams simultaneously in lockstep, on top of in some cases audio on one of them (for the cinematics). I'm also wondering if it's possible (or even useful) to do the conversion from YCbCr to depth in a pixel shader, or if it's better to just do it in CPU and separately load the resulting depth values into a locked tex. The conversion unfortunately does involve branching logic per-pixel. (There are more naive mappings that don't need branching, but they produce inferior results.) It could be reduced to a table lookup but the table would be 32MB. Programming is second-nature to me but I'm not that experienced with pix shaders and have zero knowledge of off-the-shelf video solutions. I'd therefore be interested in advice from others who may have dealt more with depth streaming, pixel shaders, and/or off-the-shelf codecs, regarding how feasible the proposed application is and what off-the-shelf video systems out there would best get along with this usage case.

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• concurrency::extent<N> from amp.h

  - by Daniel Moth

  Overview We saw in a previous post how index<N> represents a point in N-dimensional space and in this post we'll see how to define the N-dimensional space itself. With C++ AMP, an N-dimensional space can be specified with the template class extent<N> where you define the size of each dimension. From a look and feel perspective, you'd expect the programmatic interface of a point type and size type to be similar (even though the concepts are different). Indeed, exactly like index<N>, extent<N> is essentially a coordinate vector of N integers ordered from most- to least- significant, BUT each integer represents the size for that dimension (and hence cannot be negative). So, if you read the description of index, you won't be surprised with the below description of extent<N> There is the rank field returning the value of N you passed as the template parameter. You can construct one extent from another (via the copy constructor or the assignment operator), you can construct it by passing an integer array, or via convenience constructor overloads for 1- 2- and 3- dimension extents. Note that the parameterless constructor creates an extent of the specified rank with all bounds initialized to 0. You can access the components of the extent through the subscript operator (passing it an integer). You can perform some arithmetic operations between extent objects through operator overloading, i.e. ==, !=, +=, -=, +, -. There are operator overloads so that you can perform operations between an extent and an integer: -- (pre- and post- decrement), ++ (pre- and post- increment), %=, *=, /=, +=, –= and, finally, there are additional overloads for plus and minus (+,-) between extent<N> and index<N> objects, returning a new extent object as the result. In addition to the usual suspects, extent offers a contains function that tests if an index is within the bounds of the extent (assuming an origin of zero). It also has a size function that returns the total linear size of this extent<N> in units of elements. Example code extent<2> e(3, 4); _ASSERT(e.rank == 2); _ASSERT(e.size() == 3 * 4); e += 3; e[1] += 6; e = e + index<2>(3,-4); _ASSERT(e == extent<2>(9, 9)); _ASSERT( e.contains(index<2>(8, 8))); _ASSERT(!e.contains(index<2>(8, 9))); grid<N> Our upcoming pre-release bits also have a similar type to extent, grid<N>. The way you create a grid is by passing it an extent, e.g. extent<3> e(4,2,6); grid<3> g(e); I am not going to dive deeper into grid, suffice for now to think of grid<N> simply as an alias for the extent<N> object, that you create when you encounter a function that expects a grid object instead of an extent object. Usage The extent class on its own simply defines the size of the N-dimensional space. We'll see in future posts that when you create containers (arrays) and wrappers (array_views) for your data, it is an extent<N> object that you'll need to use to create those (and use an index<N> object to index into them). We'll also see that it is a grid<N> object that you pass to the new parallel_for_each function that I'll cover in the next post. Comments about this post by Daniel Moth welcome at the original blog.

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• AABB vs OBB Collision Resolution jitter on corners

  - by patt4179

  I've implemented a collision library for a character who is an AABB and am resolving collisions between AABB vs AABB and AABB vs OBB. I wanted slopes for certain sections, so I've toyed around with using several OBBs to make one, and it's working great except for one glaring issue; The collision resolution on the corner of an OBB makes the player's AABB jitter up and down constantly. I've tried a few things I've thought of, but I just can't wrap my head around what's going on exactly. Here's a video of what's happening as well as my code: Here's the function to get the collision resolution (I'm likely not doing this the right way, so this may be where the issue lies): public Vector2 GetCollisionResolveAmount(RectangleCollisionObject resolvedObject, OrientedRectangleCollisionObject b) { Vector2 overlap = Vector2.Zero; LineSegment edge = GetOrientedRectangleEdge(b, 0); if (!SeparatingAxisForRectangle(edge, resolvedObject)) { LineSegment rEdgeA = new LineSegment(), rEdgeB = new LineSegment(); Range axisRange = new Range(), rEdgeARange = new Range(), rEdgeBRange = new Range(), rProjection = new Range(); Vector2 n = edge.PointA - edge.PointB; rEdgeA.PointA = RectangleCorner(resolvedObject, 0); rEdgeA.PointB = RectangleCorner(resolvedObject, 1); rEdgeB.PointA = RectangleCorner(resolvedObject, 2); rEdgeB.PointB = RectangleCorner(resolvedObject, 3); rEdgeARange = ProjectLineSegment(rEdgeA, n); rEdgeBRange = ProjectLineSegment(rEdgeB, n); rProjection = GetRangeHull(rEdgeARange, rEdgeBRange); axisRange = ProjectLineSegment(edge, n); float axisMid = (axisRange.Maximum + axisRange.Minimum) / 2; float projectionMid = (rProjection.Maximum + rProjection.Minimum) / 2; if (projectionMid > axisMid) { overlap.X = axisRange.Maximum - rProjection.Minimum; } else { overlap.X = rProjection.Maximum - axisRange.Minimum; overlap.X = -overlap.X; } } edge = GetOrientedRectangleEdge(b, 1); if (!SeparatingAxisForRectangle(edge, resolvedObject)) { LineSegment rEdgeA = new LineSegment(), rEdgeB = new LineSegment(); Range axisRange = new Range(), rEdgeARange = new Range(), rEdgeBRange = new Range(), rProjection = new Range(); Vector2 n = edge.PointA - edge.PointB; rEdgeA.PointA = RectangleCorner(resolvedObject, 0); rEdgeA.PointB = RectangleCorner(resolvedObject, 1); rEdgeB.PointA = RectangleCorner(resolvedObject, 2); rEdgeB.PointB = RectangleCorner(resolvedObject, 3); rEdgeARange = ProjectLineSegment(rEdgeA, n); rEdgeBRange = ProjectLineSegment(rEdgeB, n); rProjection = GetRangeHull(rEdgeARange, rEdgeBRange); axisRange = ProjectLineSegment(edge, n); float axisMid = (axisRange.Maximum + axisRange.Minimum) / 2; float projectionMid = (rProjection.Maximum + rProjection.Minimum) / 2; if (projectionMid > axisMid) { overlap.Y = axisRange.Maximum - rProjection.Minimum; overlap.Y = -overlap.Y; } else { overlap.Y = rProjection.Maximum - axisRange.Minimum; } } return overlap; } And here is what I'm doing to resolve it right now: if (collisionDetection.OrientedRectangleAndRectangleCollide(obb, player.PlayerCollision)) { var resolveAmount = collisionDetection.GetCollisionResolveAmount(player.PlayerCollision, obb); if (Math.Abs(resolveAmount.Y) < Math.Abs(resolveAmount.X)) { var roundedAmount = (float)Math.Floor(resolveAmount.Y); player.PlayerCollision._position.Y -= roundedAmount; } else if (Math.Abs(resolveAmount.Y) <= 30.0f) //Catch cases where the player should be able to step over the top of something { var roundedAmount = (float)Math.Floor(resolveAmount.Y); player.PlayerCollision._position.Y -= roundedAmount; } else { var roundedAmount = (float)Math.Floor(resolveAmount.X); player.PlayerCollision._position.X -= roundedAmount; } } Can anyone see what might be the issue here, or has anyone experienced this before that knows a possible solution? I've tried for a few days to figure this out on my own, but I'm just stumped.

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• HERMES Medical Solutions Helps Save Lives with MySQL

  - by Bertrand Matthelié

  Normal 0 false false false EN-US X-NONE X-NONE /* 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:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Cambria","serif"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} HERMES Medical Solutions was established in 1976 in Stockholm, Sweden, and is a leading innovator in medical imaging hardware/software products for health care facilities worldwide. HERMES delivers a plethora of different medical imaging solutions to optimize hospital workflow. Normal 0 false false false EN-US X-NONE X-NONE /* 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:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Cambria","serif"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} HERMES advanced algorithms make it possible to detect the smallest changes under therapies important and necessary to optimize different therapeutic methods and doses. Challenges Fighting illness & disease requires state-of-the-art imaging modalities and software in order to diagnose accurately, stage disease appropriately and select the best treatment available. Selecting and implementing a new database platform that would deliver the needed performance, reliability, security and flexibility required by the high-end medical solutions offered by HERMES. Solution Decision to migrate from in-house database to an embedded SQL database powering the HERMES products, delivered either as software, integrated hardware and software solutions, or via the cloud in a software-as-a-service configuration. Evaluation of several databases and selection of MySQL based on its high performance, ease of use and integration, and low Total Cost of Ownership. On average, between 4 and 12 Terabytes of data are stored in MySQL databases underpinning the HERMES solutions. The data generated by each medical study is indeed stored during 10 years or more after the treatment was performed. MySQL-based HERMES systems also allow doctors worldwide to conduct new drug research projects leveraging the large amount of medical data collected. Hospitals and other HERMES customers worldwide highly value the “zero administration” capabilities and reliability of MySQL, enabling them to perform medical analysis without any downtime. Relying on MySQL as their embedded database, the HERMES team has been able to increase their focus on further developing their clinical applications. HERMES Medical Solutions could leverage the Oracle Financing payment plan to spread its investment over time and make the MySQL choice even more valuable. “MySQL has proven to be an excellent database choice for us. We offer high-end medical solutions, and MySQL delivers the reliability, security and performance such solutions require.” Jan Bertling, CEO.

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• Shrinking a Linux OEL 6 virtual Box image (vdi) hosted on Windows 7

  - by AndyBaker

  v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Recently for a customer demonstration there was a requirement to build a virtual box image with Oracle Enterprise Manager Cloud Control 12c. This meant installing OEL Linux 6 as well as creating an 11gr2 database and Oracle Enterprise Manager Cloud Control 12c on a single virtual box. Storage was sized at 300Gb using dynamically allocated storage for the virtual box and about 10Gb was used for Linux and the initial build. After copying over all the binaries and performing all the installations the virtual box became in the region of 80Gb used size on the host operating system, however internally it only really needed around 20Gb. This meant 60Gb had been used when copying over all the binaries and although now free was not returned to the host operating system due to the growth of the virtual box storage '.vdi' file.  Once the ‘vdi’ storage had grown it is not shrunk automatically afterwards. Space is always tight on the laptop so it was desirable to shrink the virtual box back to a minimal size and here is the process that was followed. Install 'zerofree' Linux package into the OEL6 virtual box The RPM was downloaded and installed from a site similar to below; http://rpm.pbone.net/index.php3/stat/4/idpl/12548724/com/zerofree-1.0.1-5.el5.i386.rpm.html A simple internet search for ’zerofree Linux rpm’ was easy to perform and find the required rpm. Execute 'zerofree' package on the desired Linux file system To execute this package the desired file system needs to be mounted read only. The following steps outline this process. As root: # umount /u01 As root:# mount –o ro –t ext4 /u01 NOTE: The –o is options and the –t is the file system type found in the /etc/fstab. Next run zerofree against the required storage, this is located by a simple ‘df –h’ command to see the device associated with the mount. As root:# zerofree –v /dev/sda11   NOTE: This takes a while to run but the ‘-v’ option gives feedback on the process. What does Zerofree do? Zerofree’s purpose is to go through the file system and zero out any unused sectors on the volume so that the later stages can shrink the virtual box storage obtaining the free space back. When zerofree has completed the virtual box can be shutdown as the last stage is performed on the physical host where the virtual box vdi files are located. Compact the virtual box ‘.vdi’ files The final stage is to get virtual box to shrink back the storage that has been correctly flagged as free space after executing zerofree. On the physical host in this case a windows 7 laptop a DOS window was opened. At the prompt the first step is to put the virtual box binaries onto the PATH. C:\ >echo %PATH%   The above shows the current value of the PATH environment variable. C:\ >set PATH=%PATH%;c:\program files\Oracle\Virtual Box;   The above adds onto the existing path the virtual box binary location. C:\>cd c:\Users\xxxx\OEL6.1   The above changes directory to where the VDI files are located for the required virtual box machine. C:\Users\xxxxx\OEL6.1>VBoxManage.exe modifyhd zzzzzz.vdi compact  NOTE: The zzzzzz.vdi is the name of the required vdi file to shrink. Finally the above command is executed to perform the compact operation on the ‘.vdi’ file(s). This also takes a long time to complete but shrinks the VDI file back to a minimum size. In the case of the demonstration virtual box OEM12c this reduced the virtual box to 20Gb from 80Gb which was a great outcome to achieve.

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• Criminals and Other Illegal Characters

  - by Most Valuable Yak (Rob Volk)

  SQLTeam's favorite Slovenian blogger Mladen (b | t) had an interesting question on Twitter: http://www.twitter.com/MladenPrajdic/status/347057950470307841 I liked Kendal Van Dyke's (b | t) reply: http://twitter.com/SQLDBA/status/347058908801667072 And he was right!  This is one of those pretty-useless-but-sounds-interesting propositions that I've based all my presentations on, and most of my blog posts. If you read all the replies you'll see a lot of good suggestions.  I particularly like Aaron Bertrand's (b | t) idea of going into the Unicode character set, since there are over 65,000 characters available.  But how to find an illegal character?  Detective work? I'm working on the premise that if SQL Server will reject it as a name it would throw an error.  So all we have to do is generate all Unicode characters, rename a database with that character, and catch any errors. It turns out that dynamic SQL can lend a hand here: IF DB_ID(N'a') IS NULL CREATE DATABASE [a]; DECLARE @c INT=1, @sql NVARCHAR(MAX)=N'', @err NVARCHAR(MAX)=N''; WHILE @c<65536 BEGIN BEGIN TRY SET @sql=N'alter database ' + QUOTENAME(CASE WHEN @c=1 THEN N'a' ELSE NCHAR(@c-1) END) + N' modify name=' + QUOTENAME(NCHAR(@c)); RAISERROR(N'*** Trying %d',10,1,@c) WITH NOWAIT; EXEC(@sql); SET @c+=1; END TRY BEGIN CATCH SET @err=ERROR_MESSAGE(); RAISERROR(N'Ooops - %d - %s',10,1,@c,@err) WITH NOWAIT; BREAK; END CATCH END SET @sql=N'alter database ' + QUOTENAME(NCHAR(@c-1)) + N' modify name=[a]'; EXEC(@sql); The script creates a dummy database "a" if it doesn't already exist, and only tests single characters as a database name.  If you have databases with single character names then you shouldn't run this on that server. It takes a few minutes to run, but if you do you'll see that no errors are thrown for any of the characters.  It seems that SQL Server will accept any character, no matter where they're from.  (Well, there's one, but I won't tell you which. Actually there's 2, but one of them requires some deep existential thinking.) The output is also interesting, as quite a few codes do some weird things there.  I'm pretty sure it's due to the font used in SSMS for the messages output window, not all characters are available.  If you run it using the SQLCMD utility, and use the -o switch to output to a file, and -u for Unicode output, you can open the file in Notepad or another text editor and see the whole thing. I'm not sure what character I'd recommend to answer Mladen's question.  I think the standard tab (ASCII 9) is fine.  There's also several specific separator characters in the original ASCII character set (decimal 28-31). But of all the choices available in Unicode whitespace, I think my favorite would be the Mongolian Vowel Separator.  Or maybe the zero-width space. (that'll be fun to print!)  And since this is Mladen we're talking about, here's a good selection of "intriguing" characters he could use.

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• Validation and authorization in layered architecture

  - by SonOfPirate

  I know you are thinking (or maybe yelling), "not another question asking where validation belongs in a layered architecture?!?" Well, yes, but hopefully this will be a little bit of a different take on the subject. I am a firm believer that validation takes many forms, is context-based and varies at each level of the architecture. That is the basis for the post - helping to identify what type of validation should be performed in each layer. In addition, a question that often comes up is where authorization checks belong. The example scenario comes from an application for a catering business. Periodically during the day, a driver may turn in to the office any excess cash they've accumulated while taking the truck from site to site. The application allows a user to record the 'cash drop' by collecting the driver's ID, and the amount. Here's some skeleton code to illustrate the layers involved: public class CashDropApi // This is in the Service Facade Layer { [WebInvoke(Method = "POST")] public void AddCashDrop(NewCashDropContract contract) { // 1 Service.AddCashDrop(contract.Amount, contract.DriverId); } } public class CashDropService // This is the Application Service in the Domain Layer { public void AddCashDrop(Decimal amount, Int32 driverId) { // 2 CommandBus.Send(new AddCashDropCommand(amount, driverId)); } } internal class AddCashDropCommand // This is a command object in Domain Layer { public AddCashDropCommand(Decimal amount, Int32 driverId) { // 3 Amount = amount; DriverId = driverId; } public Decimal Amount { get; private set; } public Int32 DriverId { get; private set; } } internal class AddCashDropCommandHandler : IHandle<AddCashDropCommand> { internal ICashDropFactory Factory { get; set; } // Set by IoC container internal ICashDropRepository CashDrops { get; set; } // Set by IoC container internal IEmployeeRepository Employees { get; set; } // Set by IoC container public void Handle(AddCashDropCommand command) { // 4 var driver = Employees.GetById(command.DriverId); // 5 var authorizedBy = CurrentUser as Employee; // 6 var cashDrop = Factory.CreateCashDrop(command.Amount, driver, authorizedBy); // 7 CashDrops.Add(cashDrop); } } public class CashDropFactory { public CashDrop CreateCashDrop(Decimal amount, Employee driver, Employee authorizedBy) { // 8 return new CashDrop(amount, driver, authorizedBy, DateTime.Now); } } public class CashDrop // The domain object (entity) { public CashDrop(Decimal amount, Employee driver, Employee authorizedBy, DateTime at) { // 9 ... } } public class CashDropRepository // The implementation is in the Data Access Layer { public void Add(CashDrop item) { // 10 ... } } I've indicated 10 locations where I've seen validation checks placed in code. My question is what checks you would, if any, be performing at each given the following business rules (along with standard checks for length, range, format, type, etc): The amount of the cash drop must be greater than zero. The cash drop must have a valid Driver. The current user must be authorized to add cash drops (current user is not the driver). Please share your thoughts, how you have or would approach this scenario and the reasons for your choices.

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• Using WKA in Large Coherence Clusters (Disabling Multicast)

  - by jpurdy

  Disabling hardware multicast (by configuring well-known addresses aka WKA) will place significant stress on the network. For messages that must be sent to multiple servers, rather than having a server send a single packet to the switch and having the switch broadcast that packet to the rest of the cluster, the server must send a packet to each of the other servers. While hardware varies significantly, consider that a server with a single gigabit connection can send at most ~70,000 packets per second. To continue with some concrete numbers, in a cluster with 500 members, that means that each server can send at most 140 cluster-wide messages per second. And if there are 10 cluster members on each physical machine, that number shrinks to 14 cluster-wide messages per second (or with only mild hyperbole, roughly zero). It is also important to keep in mind that network I/O is not only expensive in terms of the network itself, but also the consumption of CPU required to send (or receive) a message (due to things like copying the packet bytes, processing a interrupt, etc). Fortunately, Coherence is designed to rely primarily on point-to-point messages, but there are some features that are inherently one-to-many: Announcing the arrival or departure of a member Updating partition assignment maps across the cluster Creating or destroying a NamedCache Invalidating a cache entry from a large number of client-side near caches Distributing a filter-based request across the full set of cache servers (e.g. queries, aggregators and entry processors) Invoking clear() on a NamedCache The first few of these are operations that are primarily routed through a single senior member, and also occur infrequently, so they usually are not a primary consideration. There are cases, however, where the load from introducing new members can be substantial (to the point of destabilizing the cluster). Consider the case where cluster in the first paragraph grows from 500 members to 1000 members (holding the number of physical machines constant). During this period, there will be 500 new member introductions, each of which may consist of several cluster-wide operations (for the cluster membership itself as well as the partitioned cache services, replicated cache services, invocation services, management services, etc). Note that all of these introductions will route through that one senior member, which is sharing its network bandwidth with several other members (which will be communicating to a lesser degree with other members throughout this process). While each service may have a distinct senior member, there's a good chance during initial startup that a single member will be the senior for all services (if those services start on the senior before the second member joins the cluster). It's obvious that this could cause CPU and/or network starvation. In the current release of Coherence (3.7.1.3 as of this writing), the pure unicast code path also has less sophisticated flow-control for cluster-wide messages (compared to the multicast-enabled code path), which may also result in significant heap consumption on the senior member's JVM (from the message backlog). This is almost never a problem in practice, but with sufficient CPU or network starvation, it could become critical. For the non-operational concerns (near caches, queries, etc), the application itself will determine how much load is placed on the cluster. Applications intended for deployment in a pure unicast environment should be careful to avoid excessive dependence on these features. Even in an environment with multicast support, these operations may scale poorly since even with a constant request rate, the underlying workload will increase at roughly the same rate as the underlying resources are added. Unless there is an infrastructural requirement to the contrary, multicast should be enabled. If it can't be enabled, care should be taken to ensure the added overhead doesn't lead to performance or stability issues. This is particularly crucial in large clusters.

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• I need help with 2D collision response (of stacking rotating polygons, with friction and gravity, for a game)

  - by Register Sole

  Hi I am looking for suggestions on how to write a collision response for game programming purpose (so not a scientific simulation). I am dealing with 2D polygons that are rotating, and I want them to be able to stack. I also want friction and gravity. I have a detection mechanism that returns the separating axis, how long the polygons are overlapping, and up to 2 points of contact. For the response, I am currently using an impulse-based response, which main idea is: find the separating axis, length of overlap, and the point of contact (if there are two, pick a random point between to simulate averaged force. i believe there are better ways than this) separate the object (modifying their positions, taking into account of their masses. i do not separate them completely though, to keep track that they are colliding to reduce jitter) calculate normal force based on the coefficient of restitution as if there is no friction. calculate friction, as if there is no normal force. I also assume that the direction of the friction is the same throughout the collision. apply the two forces (which result in a rather inaccurate result, since each force is calculated as if the other is not present. for non-rotating bodies though, this method is exact) I am aware that this method requires the coefficient of friction to be sufficiently small due to the assumption that the direction of friction stays the same in a collision. Also, the result is visually satisfying if gravity is not present. However, when there is gravity, objects on ground jitter and drift (even with zero coefficient of restitution)! It also happens for stacking objects. Larger coefficient of restitution and gravity increase the jittering. I hope you can help me with this. Some things i would like to know more about is how to handle collision with two point of contacts (how to end up having an object sitting still on the ground?), how to reduce, and prevent if possible, jitter and drift (do people use the most accurate method possible, or is there a trick to overcome this?), and how to handle multiple objects collision (for example, in the case of stacking objects, how do I check collisions between all of them and keep them all stable at every frame so they don't jitter?). A total reformulation of my algorithm is also welcomed, as long as it works. Another thing to note is that I am not making a Physics game, so I only need a visually satisfying response (though a realistic response is preferable, if it is not performance-heavy). But surely jittering and drifting objects on flat ground are not at all acceptable. In addition, I am a Physics student, so feel free to talk about impulse and whatever needed. Finally, I'm sorry for the long post. I tried to be as concise as I can. Thank you for reading it! EDIT It seems what I didn't manage to come up all this time is to separate resting contact as a class of its own and how to solve them. Currently reading the paper suggested by Jedediah. More suggestions on the topic are welcome :) CASE CLOSED After reading various papers referenced in the paper, successfully implemented simultaneous impulse method (referring to the original paper by Erin Catto, [Catt05]). Thanks maaaan!! The paper is wonderful. The current system is visibly much better than the previous. Still haven't separated resting contact as a class of its own though, which brings me to my next question. Love you all! Haha (sorry, I'm just so happy thanks to you).

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• eth0 and eth1 both assigned same IP on boot

  - by Banjer

  I have a physical SLES 11 SP2 server on a Sun Fire x4140 that is giving me problems with networking upon reboot. The NICs are onboard. The networking appears successful during boot, but network services such as nfs fail hard. This is because eth0 and eth1 are both receiving the same configuration and are both ifup-ed. Once everything times out and I'm at the console, ifconfig shows that eth0 and eth1 are UP and running with the same IP. Attempting to ping anything in that subnet fails. Restarting the network service fixes the issue. eth0 is the correct NIC that should be configured as primary, per the MAC address. Question: Whats causing eth1 to be brought up with the same config as eth0?? I do not have a config script set up for eth1: banjer@harp:~> ls -la /etc/sysconfig/network/ total 104 drwxr-xr-x 6 root root 4096 Jun 11 12:21 . drwxr-xr-x 6 root root 4096 Apr 10 09:46 .. -rw-r--r-- 1 root root 13916 Apr 10 09:32 config -rw-r--r-- 1 root root 9952 Apr 10 09:36 dhcp -rw------- 1 root root 180 Jun 11 12:21 ifcfg-eth0 -rw------- 1 root root 180 Jun 11 12:21 ifcfg-eth3 -rw------- 1 root root 172 Feb 1 08:32 ifcfg-lo -rw-r--r-- 1 root root 29333 Feb 1 08:32 ifcfg.template drwxr-xr-x 2 root root 4096 Apr 10 09:32 if-down.d -rw-r--r-- 1 root root 239 Feb 1 08:32 ifroute-lo drwxr-xr-x 2 root root 4096 Apr 10 09:33 if-up.d drwx------ 2 root root 4096 May 5 2010 providers -rw-r--r-- 1 root root 25 Nov 16 2010 routes drwxr-xr-x 2 root root 4096 Apr 10 09:36 scripts On a side note, eth3 is also configured with an IP in a different subnet, but this has not posed any problems. FYI the kernel module being used is forcedeth. banjer@harp:~> sudo cat /etc/sysconfig/network/ifcfg-eth0 BOOTPROTO='static' BROADCAST='' ETHTOOL_OPTIONS='' IPADDR='172.21.64.25/20' MTU='' NAME='MCP55 Ethernet' NETWORK='' REMOTE_IPADDR='' STARTMODE='auto' USERCONTROL='no' ONBOOT="yes" Here's eth3 in case you need to see it: banjer@harp:~> sudo cat /etc/sysconfig/network/ifcfg-eth3 BOOTPROTO='static' BROADCAST='' ETHTOOL_OPTIONS='' IPADDR='172.11.200.4/24' MTU='' NAME='MCP55 Ethernet' NETWORK='' REMOTE_IPADDR='' STARTMODE='auto' USERCONTROL='no' ONBOOT="yes" Perhaps is something related to udev? 70-persistent-net-rules looks OK to me, but I may not understand it completely. banjer@harp:~> cat /etc/udev/rules.d/70-persistent-net.rules # This file was automatically generated by the /lib/udev/write_net_rules # program, run by the persistent-net-generator.rules rules file. # # You can modify it, as long as you keep each rule on a single # line, and change only the value of the NAME= key. # PCI device 0x10de:0x0373 (forcedeth) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:18:4f:8d:85:4c", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth2" # PCI device 0x10de:0x0373 (forcedeth) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:18:4f:8d:85:4a", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0" # PCI device 0x10de:0x0373 (forcedeth) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:18:4f:8d:85:4b", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth1" # PCI device 0x10de:0x0373 (forcedeth) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:18:4f:8d:85:4d", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth3" # PCI device 0x1077:0x3032 (qla3xxx) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:c1:dd:0e:34:6c", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth4" Any other thoughts on what would cause this?

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• Can't get network bridging to work

  - by Antonis Christofides

  I'm trying to make network bridging to work on a Debian squeeze (I'm experimenting in order to make a QEMU/KVM virtual machine that will be visible to the outside network as if it were a distinct machine). The problem is that when I type brctl addif br0 eth0 then I lose connectivity to the network until I type brctl delif br0 eth0. More specifically, here's how my machine looks like before I do anything (essentially eth0 is listening on 147.102.160.153): root@laura:/home/anthony# ip addr show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 8c:73:6e:db:1c:1b brd ff:ff:ff:ff:ff:ff inet 147.102.160.153/24 brd 147.102.160.255 scope global eth0 inet6 2001:648:2000:a0:8e73:6eff:fedb:1c1b/64 scope global dynamic valid_lft 2591848sec preferred_lft 604648sec inet6 fe80::8e73:6eff:fedb:1c1b/64 scope link valid_lft forever preferred_lft forever 3: wlan0: <BROADCAST,MULTICAST> mtu 1500 qdisc mq state DOWN qlen 1000 link/ether 4c:ed:de:8e:44:d7 brd ff:ff:ff:ff:ff:ff 4: vboxnet0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000 link/ether 0a:00:27:00:00:00 brd ff:ff:ff:ff:ff:ff 5: pan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN link/ether ee:7c:88:59:d0:e8 brd ff:ff:ff:ff:ff:ff Now let me add the bridge: root@laura:/home/anthony# brctl addbr br0 root@laura:/home/anthony# ip tuntap add dev tap0 mode tap root@laura:/home/anthony# ip link set tap0 up root@laura:/home/anthony# brctl addif br0 tap0 Until here everything continues to work normally. Finally, I try to add eth0 to the bridge: root@laura:/home/anthony# brctl addif br0 eth0 At this point, I no longer have a network connection. If I try to ping something, it tells "Destination Host Unreachable". The output of ip addr show seems normal: root@laura:/home/anthony# ip addr show 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 8c:73:6e:db:1c:1b brd ff:ff:ff:ff:ff:ff inet 147.102.160.153/24 brd 147.102.160.255 scope global eth0 inet6 2001:648:2000:a0:8e73:6eff:fedb:1c1b/64 scope global dynamic valid_lft 2591908sec preferred_lft 604708sec inet6 fe80::8e73:6eff:fedb:1c1b/64 scope link valid_lft forever preferred_lft forever [snip wlan0, vboxnet0 and pan0, which are down and irrelevant] 8: br0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN link/ether 16:30:f2:67:ab:75 brd ff:ff:ff:ff:ff:ff 9: tap0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 500 link/ether 16:30:f2:67:ab:75 brd ff:ff:ff:ff:ff:ff inet6 fe80::1430:f2ff:fe67:ab75/64 scope link valid_lft forever preferred_lft forever Also: root@laura:/home/anthony# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 147.102.160.0 0.0.0.0 255.255.255.0 U 1 0 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth0 0.0.0.0 147.102.160.200 0.0.0.0 UG 0 0 0 eth0 I can't understand what I'm doing wrong. I want the machine to continue to listen on 147.102.160.153 on eth0, and in addition to that I want to have a tap0 interface, bridged to eth0, that will be available to the guest machine so that the latter listens on another ip address (say 147.102.160.205). (If there's another way to achieve what I want, I'm also interested.)

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• Inconsistent file downloads of (what should be) the same file

  - by Austin A.

  I'm working on a system that archives large collections of timetstamped images. Part of the system deals with saving an image to a growing .zip file. This morning I noticed that the log system said that an image was successfully downloaded and placed in the zip file, but when I downloaded the .zip (from an apache alias running on our server), the images didn't match the log. For example, although the log said that camera 3484 captured on January 17, 2011, when I download from the apache alias, the downloaded zip file only contains images up to January 14. So, I sshed onto the server, and unzipped the file in its own directory, and that zip file has images from January 14 to today (January 17). What strikes me as odd is that this should be the exact same file as the one I downloaded from the apache alias. Other experiments: I scp-ed the file from the server to my local machine, and the zip file has the newer images. But when I use an SCP client (in this case, Fugu for OSX), I get the zip file for the older images. In short: unzipping a file on the server or after downloading through scp or after downloading through wget gives one zip file, but unzipping a file from Chrome, Firefox, or SCP client gives a different zip file, when they should be exactly the same. Unzipping on the server... [user@server ~]$ cd /export1/amos/images/2011/84/3484/00003484/ [user@server 00003484]$ ls -la total 6180 drwxr-sr-x 2 user groupname 24 Jan 17 11:20 . drwxr-sr-x 4 user groupname 36 Jan 11 19:58 .. -rw-r--r-- 1 user groupname 6309980 Jan 17 12:05 2011.01.zip [user@server 00003484]$ unzip 2011.01.zip Archive: 2011.01.zip extracting: 20110114_140547.jpg extracting: 20110114_143554.jpg replace 20110114_143554.jpg? [y]es, [n]o, [A]ll, [N]one, [r]ename: y extracting: 20110114_143554.jpg extracting: 20110114_153458.jpg (...bunch of files...) extracting: 20110117_170459.jpg extracting: 20110117_173458.jpg extracting: 20110117_180501.jpg Using the wget through apache alias. local:~ user$ wget http://example.com/zipfiles/2011/84/3484/00003484/2011.01.zip --12:38:13-- http://example.com/zipfiles/2011/84/3484/00003484/2011.01.zip => `2011.01.zip' Resolving example.com... ip.ip.ip.ip Connecting to example.com|ip.ip.ip.ip|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 6,327,747 (6.0M) [application/zip] 100% [=====================================================================================================>] 6,327,747 1.03M/s ETA 00:00 12:38:56 (143.23 KB/s) - `2011.01.zip' saved [6327747/6327747] local:~ user$ unzip 2011.01.zip Archive: 2011.01.zip extracting: 20110114_140547.jpg (... same as before...) extracting: 20110117_183459.jpg Using scp to grab the zip local:~ user$ scp user@server:/export1/amos/images/2011/84/3484/00003484/2011.01.zip . 2011.01.zip 100% 6179KB 475.3KB/s 00:13 local:~ user$ unzip 2011.01.zip Archive: 2011.01.zip extracting: 20110114_140547.jpg (...same as before...) extracting: 20110117_183459.jpg Using Fugu to download 2011.01.zip from /export1/amos/images/2011/84/3484/00003484/ gives images 20110113_090457.jpg through 201100114_010554.jpg Using Firefox to download 2011.01.zip from http://example.com/zipfiles/2011/84/3484/00003484/2011.01.zip gives images 20110113_090457.jpg through 201100114_010554.jpg Using Chrome gives same results as Firefox. Relevant section from apache httpd.conf: # ScriptAlias: This controls which directories contain server scripts. # ScriptAliases are essentially the same as Aliases, except that # documents in the realname directory are treated as applications and # run by the server when requested rather than as documents sent to the client. # The same rules about trailing "/" apply to ScriptAlias directives as to # Alias. # ScriptAlias /cgi-bin/ "/var/www/cgi-bin/" Alias /zipfiles/ /export1/amos/images/

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• Installing chrome in Centos 6.2 (Final)

  - by usjes

  I need to install chrome in a dedicated centos server where I only access via ssh, it doesn't have X or any windows graphical stuff. I need it to be able to pack extensions using google-chrome --pack-extension. I tried adding this to /etc/yum.repos.d/google.repo [google-chrome] name=google-chrome - 32-bit baseurl=http://dl.google.com/linux/chrome/rpm/stable/i386 enabled=1 gpgcheck=1 gpgkey=https://dl-ssl.google.com/linux/linux_signing_key.pub And then yum install google-chrome-stable, but there's a huge list of dependencies problems: How can I install chrome without breaking anything else? UPDATE: Ok, I installed perl-CGI from .rpm because yum couldn't find it, now dependencies resolve and it show me this list of packages to install: Dependencies Resolved ============================================================================================================================================================================================================================================= Package Arch Version Repository Size ============================================================================================================================================================================================================================================= Installing: google-chrome-stable x86_64 19.0.1084.52-138391 google-chrome 35 M Installing for dependencies: ConsoleKit x86_64 0.4.1-3.el6 base 82 k ConsoleKit-libs x86_64 0.4.1-3.el6 base 17 k GConf2 x86_64 2.28.0-6.el6 base 964 k ORBit2 x86_64 2.14.17-3.1.el6 base 168 k bc x86_64 1.06.95-1.el6 base 110 k cdparanoia-libs x86_64 10.2-5.1.el6 base 47 k cups x86_64 1:1.4.2-44.el6_2.3 updates 2.3 M dbus x86_64 1:1.2.24-5.el6_1 base 207 k desktop-file-utils x86_64 0.15-9.el6 base 47 k ed x86_64 1.1-3.3.el6 base 72 k eggdbus x86_64 0.6-3.el6 base 91 k foomatic x86_64 4.0.4-1.el6_1.1 base 251 k foomatic-db noarch 4.0-7.20091126.el6 base 980 k foomatic-db-filesystem noarch 4.0-7.20091126.el6 base 4.4 k foomatic-db-ppds noarch 4.0-7.20091126.el6 base 19 M ghostscript x86_64 8.70-11.el6_2.6 updates 4.4 M ghostscript-fonts noarch 5.50-23.1.el6 base 751 k gstreamer x86_64 0.10.29-1.el6 base 764 k gstreamer-plugins-base x86_64 0.10.29-1.el6 base 942 k gstreamer-tools x86_64 0.10.29-1.el6 base 23 k iso-codes noarch 3.16-2.el6 base 2.4 M lcms-libs x86_64 1.19-1.el6 base 100 k libIDL x86_64 0.8.13-2.1.el6 base 83 k libXScrnSaver x86_64 1.2.0-1.el6 base 19 k libXfont x86_64 1.4.1-2.el6_1 base 128 k libXv x86_64 1.0.5-1.el6 base 21 k libfontenc x86_64 1.0.5-2.el6 base 24 k libgudev1 x86_64 147-2.40.el6 base 59 k libmng x86_64 1.0.10-4.1.el6 base 165 k libogg x86_64 2:1.1.4-2.1.el6 base 21 k liboil x86_64 0.3.16-4.1.el6 base 121 k libtheora x86_64 1:1.1.0-2.el6 base 129 k libvisual x86_64 0.4.0-9.1.el6 base 135 k libvorbis x86_64 1:1.2.3-4.el6_2.1 updates 168 k mailx x86_64 12.4-6.el6 base 234 k man x86_64 1.6f-29.el6 base 263 k mesa-libGLU x86_64 7.11-3.el6 base 201 k nvidia-graphics195.30-libs x86_64 195.30-120.el6 atrpms 13 M openjpeg-libs x86_64 1.3-7.el6 base 59 k pax x86_64 3.4-10.1.el6 base 69 k phonon-backend-gstreamer x86_64 1:4.6.2-20.el6 base 125 k polkit x86_64 0.96-2.el6_0.1 base 158 k poppler x86_64 0.12.4-3.el6_0.1 base 557 k poppler-data noarch 0.4.0-1.el6 base 2.2 M poppler-utils x86_64 0.12.4-3.el6_0.1 base 73 k portreserve x86_64 0.0.4-4.el6_1.1 base 22 k qt x86_64 1:4.6.2-20.el6 base 4.0 M qt-sqlite x86_64 1:4.6.2-20.el6 base 50 k qt-x11 x86_64 1:4.6.2-20.el6 base 12 M qt3 x86_64 3.3.8b-30.el6 base 3.5 M redhat-lsb x86_64 4.0-3.el6.centos base 24 k redhat-lsb-graphics x86_64 4.0-3.el6.centos base 12 k redhat-lsb-printing x86_64 4.0-3.el6.centos base 11 k sgml-common noarch 0.6.3-32.el6 base 43 k time x86_64 1.7-37.1.el6 base 26 k tmpwatch x86_64 2.9.16-4.el6 base 31 k xdg-utils noarch 1.0.2-17.20091016cvs.el6 base 58 k xml-common noarch 0.6.3-32.el6 base 9.5 k xorg-x11-font-utils x86_64 1:7.2-11.el6 base 75 k xz x86_64 4.999.9-0.3.beta.20091007git.el6 base 137 k xz-lzma-compat x86_64 4.999.9-0.3.beta.20091007git.el6 base 16 k Transaction Summary ============================================================================================================================================================================================================================================= Install 62 Package(s) Is it safe to continue and install all that or could I break something already installed?

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• Backup, Migrate or Clone Failing CentOS 4 (LVM)

  - by Hegelworm

  I've been running a BlueQuartz CentOS 4 system (Nuonce.net distro) for a few years now and although the hard drive (Deskstar) has always been a bit noisy, on a few recent occasions I've heard it having trouble spinning up. Basically, I want to clone this drive to a similar sized one (80 Gig). I've spent many hours reading upon dd, dd_rescue, rsync, clonezilla and LVM mirroring yet the sheer number of options and nightmarish accounts has left me frozen - unable to make an informed decision as to how to start. I've made a few attempts. dd failed after about 2 hours, as, although the drives appeared to be identical on the surface (ATA Seagate Barracudas, Thai not Chinese), the destination drive is slightly smaller. My most recent attempt involved using a Debian CD to format the new drive and then rsync-ing everything over and editing the new drive's grub and fstab to reflect the changes. No joy here either as I hadn't chosen LVM when partitioning the destination drive and it wouldn't boot. As you can probably tell, I'm out of my depth here and a panic-invoking mixture of caution and frustration has prompted me to sign up here. The server itself, although not strictly a production environment, has a very specific installation of Festival, LAME and ffMpeg and provides the back-end for a Text-to-Speech jQuery plugin that I've built over the last 2 years. I'm also planning to rebuild the whole TTS system on Debian as the existing CentOS system still has PHP4 etc. For now though, I'd really like to just shift everything over to a new drive. As this is my first post, please feel free to lay any house rules on me that I might've overlooked; I've been hovering around StackOverflow for a while now but have only just signed up. Many thanks. Update: Thanks for your responses so far - it's much appreciated and makes me feel a little more confident when I can double-check things here. I had the idea of doing a fresh install of CentOS (from the original disk) on the new drive so the partitions and LVM were all set up correctly (after disconnecting my source drive to prevent painful mistakes). I then booted into rescue mode from the same CD, and, to avoid a conflicting label, changed the /boot partition's label using e2label to /bootnew. I then changed the VolGroup name using lvm vgrename from VolGroup00 to VolGroup001. I could then boot with both drives in. After mounting the new drive (via its VolGroup001 alias) into /newhd, I rsync-ed over everything I could to the new drive, using -avr switches and backslashes. Like mentioned here. I then disconnected my original source drive again, booted from the liveCD again, changed back the boot partition label from /bootnew to /boot using e2label and then renamed the VolGroup back to VolGroup00. I then rebooted and it went through the familiar start-up routine only to not find a host of files in proc, usr, lib, var etc. The boot did complete but there were lots of red 'FAILS'. I could log in with my existing creds, but the network was kaput, I couldn't startX (desktop GUI) and there were also a few (a lot) of error messages pertaining to iptables. Back to square one. I naively thought I'd nailed it. Shall I just buy a bigger hard drive and attempt the dd route? I've read that this can mess with LVM setups and there's the added risk of working on two unmounted drives at once with a low-level tool. Thanks again.

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• Pass a JSON array to a WCF web service

  - by Tawani

  I am trying to pass a JSON array to a WCF service. But it doesn't seem to work. I actually pulled an array [GetStudents] out the service and sent the exact same array back to the service [SaveStudents] and nothing (empty array) was received. The JSON array is of the format: [ {"Name":"John","Age":12}, {"Name":"Jane","Age":11}, {"Name":"Bill","Age":12} ] And the contracts are of the following format: //Contracts [DataContract] public class Student{ [DataMember]public string Name { get; set; } [DataMember]public int Age{ get; set; } } [CollectionDataContract(Namespace = "")] public class Students : List<Student> { [DataMember]public Endorsements() { } [DataMember]public Endorsements(IEnumerable<Student> source) : base(source) { } } //Operations public Students GetStudents() { var result = new Students(); result.Add(new Student(){Name="John",12}); result.Add(new Student(){Name="Jane",11}); result.Add(new Student(){Name="Bill",12}); return result; } //Operations public void SaveStudents(Students list) { Console.WriteLine(list.Count); //It always returns zero } It there a particular way to send an array to a WCF REST service?

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• Managed c++ std::string not accessible in unmanaged c++

  - by Radhesham

  In unmanaged c++ dll i have a function which takes constant std::string as argument Prototype : void read ( const std::string &amp;imageSpec_ ) I call this function from managed c++ dll by passing a std::string. When i debug the unmanaged c++ code the parameter imageSpec_ shows the value correctly but does not allow me to copy that value in other variable. imageSpec_.copy( sFilename, 4052 ); It shows length of imageSpec_ as 0(zero). If i try copying like std::string sTempFileName(imageSpec_); this statement string new string is a empty string. But for std::string sTempFileName(imageSpec_.c_str()); this statement string gets copied correctly. i.e. with charpointer string is copied correctly. Copying this way will need a major change in unmanaged c++ code. I am building unmanaged code in Visual studio 6.0 and managed c++ in Visual studio 2008. Is there any specific setting or code change in managed c++ that will solve the issue?

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• Where is the documentation for MSBUILD arguments to run MSDEPLOY?

  - by Simon_Weaver

  There is an excellent PDC talk available here which describes the new MSDEPLOY features in Visual Studio 2010 - as well as how to deploy an application within TFS. The talk explains some of the command line parameters such as : /p:DeployOnBuild /p:DeployTarget=MsDeployPublish /p:CreatePackageOnPublish=True /p:MSDeployPublishMethod=InProc /p:MSDeployServiceURL=localhost /p:DeployIISAppApth="Default Web Site" But where is the documentation for this - explaining how they work and what i should use? Most of these turn up very few or zero results when searching. Isn't there some actual documentation for these parameters somewhere? I'd rather use these to deploy than try to add a command line exec command to run the package. I've managed to create a web deployment package, which TFS is copying to the output. But I'm ending up with all kinds of errors trying to actually deploy the package. Currently in my build configuration in TFS I have the following arguments for MSBuild Arguments /p:DeployOnBuild=True /p:DeployTarget=MsDeployPublish /p:Configuration=Release /p:CreatePackageOnPublish=True /p:DeployIisAppPath=staging.example.com /p:MsDeployServiceUrl=localhost This however gives me this error : Is there any actual real documentation for these arguments? It would probably take me about 5 minutes to get it running the package by the command line, but i want to get them deploying like this because it will simplify multiple configurations later.

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