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• Cloud Computing = Elasticity * Availability

  - by Herve Roggero

  What is cloud computing? Is hosting the same thing as cloud computing? Are you running a cloud if you already use virtual machines? What is the difference between Infrastructure as a Service (IaaS) and a cloud provider? And the list goes on… these questions keep coming up and all try to fundamentally explain what “cloud” means relative to other concepts. At the risk of over simplification, answering these questions becomes simpler once you understand the primary foundations of cloud computing: Elasticity and Availability.   Elasticity The basic value proposition of cloud computing is to pay as you go, and to pay for what you use. This implies that an application can expand and contract on demand, across all its tiers (presentation layer, services, database, security…).  This also implies that application components can grow independently from each other. So if you need more storage for your database, you should be able to grow that tier without affecting, reconfiguring or changing the other tiers. Basically, cloud applications behave like a sponge; when you add water to a sponge, it grows in size; in the application world, the more customers you add, the more it grows. Pure IaaS providers will provide certain benefits, specifically in terms of operating costs, but an IaaS provider will not help you in making your applications elastic; neither will Virtual Machines. The smallest elasticity unit of an IaaS provider and a Virtual Machine environment is a server (physical or virtual). While adding servers in a datacenter helps in achieving scale, it is hardly enough. The application has yet to use this hardware.  If the process of adding computing resources is not transparent to the application, the application is not elastic.   As you can see from the above description, designing for the cloud is not about more servers; it is about designing an application for elasticity regardless of the underlying server farm.   Availability The fact of the matter is that making applications highly available is hard. It requires highly specialized tools and trained staff. On top of it, it's expensive. Many companies are required to run multiple data centers due to high availability requirements. In some organizations, some data centers are simply on standby, waiting to be used in a case of a failover. Other organizations are able to achieve a certain level of success with active/active data centers, in which all available data centers serve incoming user requests. While achieving high availability for services is relatively simple, establishing a highly available database farm is far more complex. In fact it is so complex that many companies establish yearly tests to validate failover procedures.   To a certain degree certain IaaS provides can assist with complex disaster recovery planning and setting up data centers that can achieve successful failover. However the burden is still on the corporation to manage and maintain such an environment, including regular hardware and software upgrades. Cloud computing on the other hand removes most of the disaster recovery requirements by hiding many of the underlying complexities.   Cloud Providers A cloud provider is an infrastructure provider offering additional tools to achieve application elasticity and availability that are not usually available on-premise. For example Microsoft Azure provides a simple configuration screen that makes it possible to run 1 or 100 web sites by clicking a button or two on a screen (simplifying provisioning), and soon SQL Azure will offer Data Federation to allow database sharding (which allows you to scale the database tier seamlessly and automatically). Other cloud providers offer certain features that are not available on-premise as well, such as the Amazon SC3 (Simple Storage Service) which gives you virtually unlimited storage capabilities for simple data stores, which is somewhat equivalent to the Microsoft Azure Table offering (offering a server-independent data storage model). Unlike IaaS providers, cloud providers give you the necessary tools to adopt elasticity as part of your application architecture.    Some cloud providers offer built-in high availability that get you out of the business of configuring clustered solutions, or running multiple data centers. Some cloud providers will give you more control (which puts some of that burden back on the customers' shoulder) and others will tend to make high availability totally transparent. For example, SQL Azure provides high availability automatically which would be very difficult to achieve (and very costly) on premise.   Keep in mind that each cloud provider has its strengths and weaknesses; some are better at achieving transparent scalability and server independence than others.    Not for Everyone Note however that it is up to you to leverage the elasticity capabilities of a cloud provider, as discussed previously; if you build a website that does not need to scale, for which elasticity is not important, then you can use a traditional host provider unless you also need high availability. Leveraging the technologies of cloud providers can be difficult and can become a journey for companies that build their solutions in a scale up fashion. Cloud computing promises to address cost containment and scalability of applications with built-in high availability. If your application does not need to scale or you do not need high availability, then cloud computing may not be for you. In fact, you may pay a premium to run your applications with cloud providers due to the underlying technologies built specifically for scalability and availability requirements. And as such, the cloud is not for everyone.   Consistent Customer Experience, Predictable Cost With all its complexities, buzz and foggy definition, cloud computing boils down to a simple objective: consistent customer experience at a predictable cost.  The objective of a cloud solution is to provide the same user experience to your last customer than the first, while keeping your operating costs directly proportional to the number of customers you have. Making your applications elastic and highly available across all its tiers, with as much automation as possible, achieves the first objective of a consistent customer experience. And the ability to expand and contract the infrastructure footprint of your application dynamically achieves the cost containment objectives.     Herve Roggero is a SQL Azure MVP and co-author of Pro SQL Azure (APress).  He is the co-founder of Blue Syntax Consulting (www.bluesyntax.net), a company focusing on cloud computing technologies helping customers understand and adopt cloud computing technologies. For more information contact herve at hroggero @ bluesyntax.net .

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• Expectations + Rewards = Innovation

  - by D'Arcy Lussier

  “Innovation” is a heavy word. We regard those that embrace it as “Innovators”. We describe organizations as being “Innovative”. We hold those associated with the word in high regard, even though its dictionary definition is very simple: Introducing something new. What our culture has done is wrapped Innovation in white robes and a gold crown. Innovation is rarely just introducing something new. Innovations and innovators are typically associated with other terms: groundbreaking, genius, industry-changing, creative, leading. Being a true innovator and creating innovations are a big deal, and something companies try to strive for…or at least say they strive for. There’s huge value in being recognized as an innovator in an industry, since the idea is that innovation equates to increased profitability. IBM ran an ad a few years back that showed what their view of innovation is: “The point of innovation is to make actual money.” If the money aspect makes you feel uneasy, consider it another way: the point of innovation is to <insert payoff here>. Companies that innovate will be more successful. Non-profits that innovate can better serve their target clients. Governments that innovate can better provide services to their citizens. True innovation is not easy to come by though. As with anything in business, how well an organization will innovate is reliant on the employees it retains, the expectations placed on those employees, and the rewards available to them. In a previous blog post I talked about one formula: Right Employees + Happy Employees = Productive Employees I want to introduce a new one, that builds upon the previous one: Expectations + Rewards = Innovation  The level of innovation your organization will realize is directly associated with the expectations you place on your staff and the rewards you make available to them. Expectations We may feel uncomfortable with the idea of placing expectations on our staff, mainly because expectation has somewhat of a negative or cold connotation to it: “I expect you to act this way or else!” The problem is in the or-else part…we focus on the negative aspects of failing to meet expectations instead of looking at the positive side. “I expect you to act this way because it will produce <insert benefit here>”. Expectations should not be set to punish but instead be set to ensure quality. At a recent conference I spoke with some Microsoft employees who told me that you have five years from starting with the company to reach a “Senior” level. If you don’t, then you’re let go. The expectation Microsoft placed on their staff is that they should be working towards improving themselves, taking more responsibility, and thus ensure that there is a constant level of quality in the workforce. Rewards Let me be clear: a paycheck is not a reward. A paycheck is simply the employer’s responsibility in the employee/employer relationship. A paycheck will never be the key motivator to drive innovation. Offering employees something over and above their required compensation can spur them to greater performance and achievement. Working in the food service industry, this tactic was used again and again: whoever has the highest sales over lunch will receive a free lunch/gift certificate/entry into a draw/etc. There was something to strive for, to try beyond the baseline of what our serving jobs were. It was through this that innovative sales techniques would be tried and honed, with key servers being top sellers time and time again. At a code camp I spoke at, I was amazed to see that all the employees from one company receive $100 Visa gift cards as a thank you for taking time to speak. Again, offering something over and above that can give that extra push for employees. Rewards work. But what about the fairness angle? In the restaurant example I gave, there were servers that would never win the competition. They just weren’t good enough at selling and never seemed to get better. So should those that did work at performing better and produce more sales for the restaurant not get rewarded because those who weren’t working at performing better might get upset? Of course not! Organizations succeed because of their top performers and those that strive to join their ranks. The Expectation/Reward Graph While the Expectations + Rewards = Innovation formula may seem like a simple mathematics formula, there’s much more going under the hood. In fact there are three different outcomes that could occur based on what you put in as values for Expectations and Rewards. Consider the graph below and the descriptions that follow: Disgruntled – High Expectation, Low Reward I worked at a company where the mantra was “Company First, Because We Pay You”. Even today I still hear stories of how this sentiment continues to be perpetuated: They provide you a paycheck and a means to live, therefore you should always put them as your top priority. Of course, this is a huge imbalance in the expectation/reward equation. Why would anyone willingly meet high expectations of availability, workload, deadlines, etc. when there is no reward other than a paycheck to show for it? Remember: paychecks are not rewards! Instead, you see employees be disgruntled which not only affects the level of production but also the level of quality within an organization. It also means that you see higher turnover. Complacent – Low Expectation, Low Reward Complacency is a systemic problem that typically exists throughout all levels of an organization. With no real expectations or rewards, nobody needs to excel. In fact, those that do try to innovate, improve, or introduce new things into the organization might be shunned or pushed out by the rest of the staff who are just doing things the same way they’ve always done it. The bigger issue for the organization with low/low values is that at best they’ll never grow beyond their current size (and may shrink actually), and at worst will cease to exist. Entitled – Low Expectation, High Reward It’s one thing to say you have the best people and reward them as such, but its another thing to actually have the best people and reward them as such. Organizations with Entitled employees are the former: their organization provides them with all types of comforts, benefits, and perks. But there’s no requirement before the rewards are dolled out, and there’s no short-list of who receives the rewards. Everyone in the company is treated the same and is given equal share of the spoils. Entitlement is actually almost identical with Complacency with one notable difference: just try to introduce higher expectations into an entitled organization! Entitled employees have been spoiled for so long that they can’t fathom having rewards taken from them, or having to achieve specific levels of performance before attaining them. Those running the organization also buy in to the Entitled sentiment, feeling that they must persist the same level of comforts to appease their staff…even though the quality of the employee pool may be suspect. Innovative – High Expectation, High Reward Finally we have the Innovative organization which places high expectations but also provides high rewards. This organization gets it: if you truly want the best employees you need to apply equal doses of pressure and praise. Realize that I’m not suggesting crazy overtime or un-realistic working conditions. I do not agree with the “Glengary-Glenross” method of encouragement. But as anyone who follows sports can tell you, the teams that win are the ones where the coaches push their players to be their best; to achieve new levels of performance that they didn’t know they could receive. And the result for the players is more money, fame, and opportunity. It’s in this environment that organizations can focus on innovation – true innovation that builds the business and allows everyone involved to truly benefit. In Closing Organizations love to use the word “Innovation” and its derivatives, but very few actually do innovate. For many, the term has just become another marketing buzzword to lump in with all the other business terms that get overused. But for those organizations that truly get the value of innovation, they will be the ones surging forward while other companies simply fade into the background. And they will be the organizations that expect more from their employees, and give them their just rewards.

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• Auto DOP and Concurrency

  - by jean-pierre.dijcks

  After spending some time in the cloud, I figured it is time to come down to earth and start discussing some of the new Auto DOP features some more. As Database Machines (the v2 machine runs Oracle Database 11.2) are effectively selling like hotcakes, it makes some sense to talk about the new parallel features in more detail. For basic understanding make sure you have read the initial post. The focus there is on Auto DOP and queuing, which is to some extend the focus here. But now I want to discuss the concurrency a little and explain some of the relevant parameters and their impact, specifically in a situation with concurrency on the system. The goal of Auto DOP The idea behind calculating the Automatic Degree of Parallelism is to find the highest possible DOP (ideal DOP) that still scales. In other words, if we were to increase the DOP even more  above a certain DOP we would see a tailing off of the performance curve and the resource cost / performance would become less optimal. Therefore the ideal DOP is the best resource/performance point for that statement. The goal of Queuing On a normal production system we should see statements running concurrently. On a Database Machine we typically see high concurrency rates, so we need to find a way to deal with both high DOP’s and high concurrency. Queuing is intended to make sure we Don’t throttle down a DOP because other statements are running on the system Stay within the physical limits of a system’s processing power Instead of making statements go at a lower DOP we queue them to make sure they will get all the resources they want to run efficiently without trashing the system. The theory – and hopefully – practice is that by giving a statement the optimal DOP the sum of all statements runs faster with queuing than without queuing. Increasing the Number of Potential Parallel Statements To determine how many statements we will consider running in parallel a single parameter should be looked at. That parameter is called PARALLEL_MIN_TIME_THRESHOLD. The default value is set to 10 seconds. So far there is nothing new here…, but do realize that anything serial (e.g. that stays under the threshold) goes straight into processing as is not considered in the rest of this post. Now, if you have a system where you have two groups of queries, serial short running and potentially parallel long running ones, you may want to worry only about the long running ones with this parallel statement threshold. As an example, lets assume the short running stuff runs on average between 1 and 15 seconds in serial (and the business is quite happy with that). The long running stuff is in the realm of 1 – 5 minutes. It might be a good choice to set the threshold to somewhere north of 30 seconds. That way the short running queries all run serial as they do today (if it ain’t broken, don’t fix it) and allows the long running ones to be evaluated for (higher degrees of) parallelism. This makes sense because the longer running ones are (at least in theory) more interesting to unleash a parallel processing model on and the benefits of running these in parallel are much more significant (again, that is mostly the case). Setting a Maximum DOP for a Statement Now that you know how to control how many of your statements are considered to run in parallel, lets talk about the specific degree of any given statement that will be evaluated. As the initial post describes this is controlled by PARALLEL_DEGREE_LIMIT. This parameter controls the degree on the entire cluster and by default it is CPU (meaning it equals Default DOP). For the sake of an example, let’s say our Default DOP is 32. Looking at our 5 minute queries from the previous paragraph, the limit to 32 means that none of the statements that are evaluated for Auto DOP ever runs at more than DOP of 32. Concurrently Running a High DOP A basic assumption about running high DOP statements at high concurrency is that you at some point in time (and this is true on any parallel processing platform!) will run into a resource limitation. And yes, you can then buy more hardware (e.g. expand the Database Machine in Oracle’s case), but that is not the point of this post… The goal is to find a balance between the highest possible DOP for each statement and the number of statements running concurrently, but with an emphasis on running each statement at that highest efficiency DOP. The PARALLEL_SERVER_TARGET parameter is the all important concurrency slider here. Setting this parameter to a higher number means more statements get to run at their maximum parallel degree before queuing kicks in.  PARALLEL_SERVER_TARGET is set per instance (so needs to be set to the same value on all 8 nodes in a full rack Database Machine). Just as a side note, this parameter is set in processes, not in DOP, which equates to 4* Default DOP (2 processes for a DOP, default value is 2 * Default DOP, hence a default of 4 * Default DOP). Let’s say we have PARALLEL_SERVER_TARGET set to 128. With our limit set to 32 (the default) we are able to run 4 statements concurrently at the highest DOP possible on this system before we start queuing. If these 4 statements are running, any next statement will be queued. To run a system at high concurrency the PARALLEL_SERVER_TARGET should be raised from its default to be much closer (start with 60% or so) to PARALLEL_MAX_SERVERS. By using both PARALLEL_SERVER_TARGET and PARALLEL_DEGREE_LIMIT you can control easily how many statements run concurrently at good DOPs without excessive queuing. Because each workload is a little different, it makes sense to plan ahead and look at these parameters and set these based on your requirements.

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• a question on common lisp

  - by kostas

  Hello people, I'm getting crazy with a small problem here, I keep getting an error and I cant seem to figure out why, the code is supposed to change the range of a list, so if we give it a list with values (1 2 3 4) and we want to change the range in 11 to fourteen the result would be (11 12 13 14) the problem is that the last function called scale-list will give back an error saying: Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil) anybody has a clue why? I use aquamacs as an editor thanks in advance ;;finds minimum in a list (defun minimum(list) (car (sort list #'<))) ;;finds maximum in a list (defun maximum(list) (car (sort list #'>))) ;;calculates the range of a list (defun range(list) (- (maximum list) (minimum list))) ;;this codes scales a value from a list (defun scale-value(list low high n) (+ (/ (* (- (nth (- n 1) list) (minimum list)) (- high low)) (range list)) low)) ;and this code is supposed to scale the whole list (defun scale-list(list low high n) (unless (= n 0) (cons (scale-value list low high n) (scale-list list low high (- n 1))))) (scale-list '(0.1 0.3 0.5 0.9) 20 30 4)

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• Data management in unexpected places

  - by Ashok_Ora

  Normal 0 false false false EN-US X-NONE X-NONE Data management in unexpected places When you think of network switches, routers, firewall appliances, etc., it may not be obvious that at the heart of these kinds of solutions is an engine that can manage huge amounts of data at very high throughput with low latencies and high availability. Consider a network router that is processing tens (or hundreds) of thousands of network packets per second. So what really happens inside a router? Packets are streaming in at the rate of tens of thousands per second. Each packet has multiple attributes, for example, a destination, associated SLAs etc. For each packet, the router has to determine the address of the next “hop” to the destination; it has to determine how to prioritize this packet. If it’s a high priority packet, then it has to be sent on its way before lower priority packets. As a consequence of prioritizing high priority packets, lower priority data packets may need to be temporarily stored (held back), but addressed fairly. If there are security or privacy requirements associated with the data packet, those have to be enforced. You probably need to keep track of statistics related to the packets processed (someone’s sure to ask). You have to do all this (and more) while preserving high availability i.e. if one of the processors in the router goes down, you have to have a way to continue processing without interruption (the customer won’t be happy with a “choppy” VoIP conversation, right?). And all this has to be achieved without ANY intervention from a human operator – the router is most likely to be in a remote location – it must JUST CONTINUE TO WORK CORRECTLY, even when bad things happen. How is this implemented? As soon as a packet arrives, it is interpreted by the receiving software. The software decodes the packet headers in order to determine the destination, kind of packet (e.g. voice vs. data), SLAs associated with the “owner” of the packet etc. It looks up the internal database of “rules” of how to process this packet and handles the packet accordingly. The software might choose to hold on to the packet safely for some period of time, if it’s a low priority packet. Ah – this sounds very much like a database problem. For each packet, you have to minimally · Look up the most efficient next “hop” towards the destination. The “most efficient” next hop can change, depending on latency, availability etc. · Look up the SLA and determine the priority of this packet (e.g. voice calls get priority over data ftp) · Look up security information associated with this data packet. It may be necessary to retrieve the context for this network packet since a network packet is a small “slice” of a session. The context for the “header” packet needs to be stored in the router, in order to make this work. · If the priority of the packet is low, then “store” the packet temporarily in the router until it is time to forward the packet to the next hop. · Update various statistics about the packet. In most cases, you have to do all this in the context of a single transaction. For example, you want to look up the forwarding address and perform the “send” in a single transaction so that the forwarding address doesn’t change while you’re sending the packet. So, how do you do all this? Berkeley DB is a proven, reliable, high performance, highly available embeddable database, designed for exactly these kinds of usage scenarios. Berkeley DB is a robust, reliable, proven solution that is currently being used in these scenarios. First and foremost, Berkeley DB (or BDB for short) is very very fast. It can process tens or hundreds of thousands of transactions per second. It can be used as a pure in-memory database, or as a disk-persistent database. BDB provides high availability – if one board in the router fails, the system can automatically failover to another board – no manual intervention required. BDB is self-administering – there’s no need for manual intervention in order to maintain a BDB application. No need to send a technician to a remote site in the middle of nowhere on a freezing winter day to perform maintenance operations. BDB is used in over 200 million deployments worldwide for the past two decades for mission-critical applications such as the one described here. You have a choice of spending valuable resources to implement similar functionality, or, you could simply embed BDB in your application and off you go! I know what I’d do – choose BDB, so I can focus on my business problem. What will you do? /* 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-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

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• Problem with a recursive function to find sqrt of a number

  - by Eternal Learner

  Below is a simple program which computes sqrt of a number using Bisection. While executing this with a call like sqrtr(4,1,4) in goes into an endless recursion . I am unable to figure out why this is happening. Below is the function : double sqrtr(double N , double Low ,double High ) { double value = 0.00; double mid = (Low + High + 1)/2; if(Low == High) { value = High; } else if (N < mid * mid ) { value = sqrtr(N,Low,mid-1) ; } else if(N >= mid * mid) { value = sqrtr(N,mid,High) ; } return value; }

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• "...redeclared as different kind of symbol"?

  - by CodeNewb

  #include <stdio.h> #include <math.h> double integrateF(double low, double high) { double low = 0; double high = 20; double delta_x=0; double x, ans; double s = 1/2*exp((-x*x)/2); for(x=low;x<=high;x++) delta_x = x+delta_x; ans = delta_x*s; return ans; } It says that low and high are "redeclared as different type of symbol" and I don't know what that means. Basically, all I'm doing here (READ: trying) is integrating from low (which I set to 0) to high (20) to find the Riemann sum. The for loop looks kinda trippy too...I'm so lost.

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• Sleep/Suspend and WOL on FreeNAS

  - by Timothy R. Butler

  I am trying to figure out how to get FreeNAS 8 to sleep when inactive and, ideally, wake on lan activity (or, less ideally, wake on a WOL magic packet). However, as I've tried to search for information on how to do this, almost all discussions seem to be centered on FreeNAS 7. Also, the tools included in FreeBSD to do this seem to be missing (i.e. acpiconf, etc.). Is there a way to get FreeNAS 8 to sleep and wake so that I don't have to leave the server running all the time? Given its usage level, it seems a waste to have the server running constantly.

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• SQL Server 2008 Remote Access

  - by Timothy Strimple

  I'm having problems connecting to my SQL Server 2008 database from my computer. I have enabled remote connections as described in this answer (http://serverfault.com/questions/7798/how-to-enable-remote-connections-for-sql-server-2008). And I have added the ports listed on the microsoft support page to our Cisco Asa firewall and I'm still unable to connect. The error I'm getting from the SQL Management Studio is: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.) (Microsoft SQL Server, Error: 10060) Once again, I have double and triple checked that remote connections are enabled under the database properties and that TCP is enabled on the configuration page. I've added tcp ports 135, 1433, 1434, 2382, 2383, and 4022 as well as udp 1434 to the firewall. I've also checked to make sure that 1433 is the static port that is set in the tcp section of the database server configuration. The ports should be configured correctly in the firewall since http/https and rdp are all working and the sql server ports are setup the same way. What am I missing here? Any help you could offer would be greatly appreciated. Edit: I can connect to the server via TCP on the internal network. The servers are colocated in a datacenter and I can connect from my production box to my development box and vice versa. To me that indicates a firewall issue, but I've no idea what else to open. I've even tried allowing all tcp ports to that server without success.

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• Refurbished System Windows License Key and OEM Media

  - by Timothy R. Butler

  According to this question, it is legal to use a Windows 7 OEM license that is presently installed as a 32-bit install with a 64-bit version of Windows 7. With that in mind, I purchased several refurbished systems through TigerDirect. When I received the computers today, I found that they have a Windows 7 license key attached to them that says it is a "refurbished key." A flyer in the box also seemed to imply that this key would not work with regular OEM media. Has anyone tried using regular OEM media with a refurbished key? I had hoped to create a new 64-bit WIM image that I could use on these systems, but I don't want to try replacing the default install with this new 64-bit install only to find that the key won't validate. If it requires a special customized image, is it possible to convert another type of Windows 7 disc into the required sort much as one can convert a retail disc to an OEM one (and vise versa)?

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• Long Gigabit Ethernet Run

  - by Timothy R. Butler

  I am trying to get an Gig-E network between two buildings that are approximately 260 ft. away. While some TRENDnet switches failed to be able to connect to each other over Cat 6 at that distance, two Netgear 5-port Gig-E switches do so just fine. However, it still fails after I put in place APC PNET1GB ethernet surge protectors at each end before the line connects to the respective switches. So I find myself wondering if I simply need to find a better surge protector that doesn't degrade the signal as much (if so, what kind would you recommend?) or if I should give up on copper and use fiber between the buildings. If I opt to go the latter route, I could really use some pointers. It looks like LC connectors are the most common, but I keep running into some others as well. A media converter on each end seems like the simplest solution, but perhaps a Gig-E switch with an SFP port would make more sense? Given a very limited budget, sticking with my existing copper seems best, but if it is bound to be a headache, a 100 meter fiber cable is something I think I can swing cost wise.

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• Linux: Force fsck of a read-only mounted filesystem?

  - by Timothy Miller

  I'm developing for a headless embedded appliance, running CentOS 6.2. The user can connect a keyboard, but not a monitor, and a serial console would require opening the case, something we don't want the user to have to do. This all pretty much obviates the possibility of using a recovery USB drive to boot from, unless all it does is blindly reimage the harddrive. I would like to provide some recovery facilities, and I have written a tool that comes up on /dev/tty1 in place of getty to provide these functions. One such function is fsck. I have found out how to remount the root and other file systems read-only. Now that they are read-only, it should be safe to fsck them and then reboot. Unfortunately, fsck complains to me that the filesystems are mounted and refuses to do anything. How can I force fsck to run on a read-only mounted partition? Based on my research, this is going to have to be something obscure. "-f" just means to force repair of a clean (but unmounted) partition. I need to repair a clean or unclean mounted partition. From what I read, this is something "only experts" should do, but no one has bothered to explain how the experts do it. I'm hoping someone can reveal this to me. BTW, I've noticed that e2fsck 1.42.4 on Gentoo will let you fsck a mounted partition, even mounted read-write, but it seems only to do so if fsck is run from a terminal, so it can ask the user if they're sure they want to do something so dangerous. I'm not sure if the CentOS version does the same thing, but it appears that fsck CAN repair a mounted partition, but it flatly refuses to when not run from a terminal. One last-resort option is for me to compile my own hacked fsck. But I'm afraid I'll mess it up in some unexpected way. Thanks! Note: Originally posted here.

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• Why is (free_space + used_space) != total_size in df? [migrated]

  - by Timothy Jones

  I have a ~2TB ext4 USB external disk which is about half full: $ df Filesystem 1K-blocks Used Available Use% Mounted on /dev/sdc 1922860848 927384456 897800668 51% /media/big I'm wondering why the total size (1922860848) isn't the same as Used+Available (1825185124)? From this answer I see that 5% of the disk might be reserved for root, but that would still only take the total used to 1921328166, which is still off. Is it related to some other filesystem overhead? In case it's relevant, lsof -n | grep deleted shows no deleted files on this disk, and there are no other filesystems mounted inside this one.

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• Exchange Disconnecting on EHLO with remote telnet

  - by Timothy Baldridge

  When I go to the local terminal on my Exchange box (SBS 2008) I can do this: telnet 127.0.0.1 25 220 Exchange banner here EHLO example.com 250 Server name However when I go from another box, or from the actual IP of the server I get this: telnet 192.168.21.20 25 220 Exchange banner here EHLO example.com 421 4.4.1 Connection timed out Connection to host lost. The odd thing is, this server is currently in production and working fine (receiving mail for our entire domain). But my C# programs can't send mail to it (they get this same error). Any ideas?

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• FreeNAS AFP Doesn't Authenticate

  - by Timothy R. Butler

  I just set up a FreeNAS 8.0.3 server and am trying to use its AFP (Netatalk) service to access it via a Mac OS X Lion system. I created the ZFS volume, set its permissions to include my user in its owner group (and set group write permissions), created an AFP share with AFP3 and told that share to "allow" @uninet (my group). I have a user on the server named tbutler, matching the user on my Mac. I can see the server, "Beatrice," in Finder. When I try to login in Finder using "Connect As...," the user "tbutler" and the proper password, I am returned to the main Finder window with the black bar now saying "Connection Failed." Here's the most recent data from /var/messages on the server, which shows me trying to login both as a "Registered User" and a "Guest": Jul 30 00:29:07 freenas afpd[8972]: AFP3.3 Login by nobody Jul 30 00:29:08 freenas afpd[8972]: AFP logout by nobody Jul 30 00:29:08 freenas afpd[8972]: dsi_stream_read: len:0, unexpected EOF Jul 30 00:29:08 freenas afpd[8972]: afp_over_dsi: client logged out, terminating DSI session Jul 30 00:29:08 freenas afpd[8972]: AFP statistics: 0.14 KB read, 0.12 KB written Jul 30 00:29:14 freenas afpd[8975]: AFP3.3 Login by tbutler Jul 30 00:29:14 freenas afpd[8975]: AFP logout by tbutler Jul 30 00:29:14 freenas afpd[8975]: dsi_stream_read: len:0, unexpected EOF Jul 30 00:29:14 freenas afpd[8975]: afp_over_dsi: client logged out, terminating DSI session Jul 30 00:29:14 freenas afpd[8975]: AFP statistics: 0.62 KB read, 0.48 KB written Jul 30 00:29:20 freenas afpd[8978]: AFP3.3 Login by tbutler Jul 30 00:29:20 freenas afpd[8978]: AFP logout by tbutler Jul 30 00:29:20 freenas afpd[8978]: dsi_stream_read: len:0, unexpected EOF Jul 30 00:29:20 freenas afpd[8978]: afp_over_dsi: client logged out, terminating DSI session Jul 30 00:29:20 freenas afpd[8978]: AFP statistics: 0.62 KB read, 0.48 KB written Jul 30 00:29:27 freenas afpd[8983]: AFP3.3 Login by nobody (My clock is clearly not properly set, but be that as it may...) Any suggestions? UPDATE: Apparently this problem occurs if one gives the AFP share a password in the AFP share settings box. When I removed the password and tried to login using a user account again, it worked just fine.

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• Resizing Partitions on Live RHEL/cPanel Server

  - by Timothy R. Butler

  I've resized many partitions over the years on Linux, Windows and Mac OS X -- but always using a GUI. However, the time has come where the preset partition sizes my data center placed on my server aren't the right sizes and I need to resize a production server's disks. I could fiddle with it and probably do OK, but given that it is a production server, I wanted to get some advice about the right way to do this. I do have KVM over IP access, so if it is best to take the server offline and boot off a rescue partition, I can do that. root [/var/lib/mysql]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda2 9.9G 2.1G 7.3G 23% / tmpfs 7.8G 0 7.8G 0% /dev/shm /dev/sda1 99M 77M 18M 82% /boot /dev/sda8 884G 463G 376G 56% /home /dev/sda3 9.9G 8.0G 1.5G 85% /usr /dev/sda5 9.9G 9.1G 308M 97% /var /usr/tmpDSK 2.0G 38M 1.8G 3% /tmp As you can see /var and /usr are quite close to being full and I've actually had to symlink some logs on /usr to directories in /home to balance things out. What I would like to do is to add 6-10 GB each to /usr and /var, presumably taking the space from /home. As I think about how the disk is arranged, the best thought I've come up with is to reduce /home by 16 GB, say, and move /var to the spot freed up, then allocating /var's space to /usr. However, that would put /var at the far end of the disk, which seems less than idea, given that MySQL has all of its data on that partition. I'd love to take the space out of the closer end of /usr, but I assume that would take a very arduous (and perhaps risky) process of moving all of the data in /usr around. I seem to recall having such a process fail for me on a computer in the past. The other option might be to merge / and /usr since / is underutilized, though I'm not sure if that's a good idea. Do you have any suggestions both on the best reallocation plan and the commands to use to accomplish it? UPDATE: I should add -- here's the partition table. There's one unused partition, which, if memory serves, was the original tmp location before I created a tmp image: Name Flags Part Type FS Type [Label] Size (MB) ------------------------------------------------------------------------------ Unusable 1.05* sda1 Boot Primary Linux ext2 106.96* sda2 Primary Linux ext3 10737.42* sda3 Primary Linux ext3 10737.42* sda5 NC Logical Linux ext3 10738.47* sda6 NC Logical Linux swap / Solaris 2148.54* sda7 NC Logical Linux ext3 1074.80* sda8 NC Logical Linux ext3 964098.53*

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• nginx projects in subfolders

  - by Timothy

  I'm getting frustrated with my nginx configuration and so I'm asking for help in writing my config file to serve multiple projects from sub-directories in the same root. This isn't virtual hosting as they are all using the same host value. Perhaps an example will clarify my attempt: request 192.168.1.1/ should serve index.php from /var/www/public/ request 192.168.1.1/wiki/ should serve index.php from /var/www/wiki/public/ request 192.168.1.1/blog/ should serve index.php from /var/www/blog/public/ These projects are using PHP and use fastcgi. My current configuration is very minimal. server { listen 80 default; server_name localhost; access_log /var/log/nginx/localhost.access.log; root /var/www; index index.php index.html; location ~ \.php$ { fastcgi_pass 127.0.0.1:9000; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME /var/www$fastcgi_script_name; include fastcgi_params; } } I've tried various things with alias and rewrite but was not able to get things set correctly for fastcgi. It seems there should be a more eloquent way than writing location blocks and duplicating root, index, SCRIPT_FILENAME, etc. Any pointers to get me headed in the right direction are appreciated.

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• How to Install OS without DVD and USB boot

  - by Timothy James Reed

  I just purchased a used Dell F1D 1U rack mount server and would like to install Ubuntu or ESXi with Virtual Disks or anything for that matter. I'v read that Dell's have built in DRAC so you can access it remotely. There are 3 ethernet plugs in the back but I dont know which one to use. In the BIOS it says I can configure Remote access on [com1] or [com2] not sure if that is ethernet 1 & 2. I also set it up so to use a static IP adress. Thats as far as I have gone. Not sure what to do next. I'v Tried to do a PXE server with TFTP but get stuck at Error "cant locate file" or something like that. Not even sure I want to go that route anymore because of all the hassel of editing files. All my computers are OSX or Linux and the only Windows I have is via VMWare. What steps to i do now?

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• Stop windows-7 explorer taskbar icon changing for different locations

  - by Timothy Kane

  If I open an instance of Windows Explorer, a button appears on the taskbar; its icon matches the icon of current location in Explorer. E.g. If I've clicked on a drive (e.g. C:) then the taskbar icon changes to the drive icon. If I select the Pictures Library location, the taskbar icon changes to a little picture symbol. How can I stop this behaviour, so that the taskbar icon always shows the same icon, regardless of where I've clicked in Explorer?

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• Install Windows 8 Apps to custom directory

  - by Timothy Ford

  I'm running Windows 8 Pro on a laptop. I initially installed the OS just to fiddle round with it and get to know something I'd inevitably end up having to fix for someone. The problem being I only gave the partition about 32gb and that ran out pretty quick. I'd like to install office and get used to that as well but unfortunately I'm a few gigabytes short. I'd like to know if I can change the install location of office 2013 and other apps so that I can run them from another partition because there is no space left to the right of this partition I can't extend it.

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• Very Hot P4 3.4 GHz

  - by Timothy R. Butler

  My Pentium 4 3.4 GHz is running hot even with a new fan on my case's heatsink (80mm rated at ~ 40 CFM). If I stress the CPU, it goes over Intel's maximum temperature rating. I'm contemplating putting in a "PCI cooler" (i.e. a fan that fits into an empty PCI slot) to see if I could get better airflow in the case. The slot isn't far from the processor and heatpipes that lead from the processor to the fan, so I'm hopeful this would help, but not entirely certain. Thoughts?

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• Dropbox.py on RHEL 6

  - by Timothy R. Butler

  I'm trying to run a headless install of Dropbox on RHEL 6. The daemon seems to be running, but when I try to use Dropbox's associated dropbox.py tool to control the daemon, it fails to run with the following error: Traceback (most recent call last): File "./dropbox.py", line 26, in <module> import locale File "/usr/lib64/python2.6/locale.py", line 202, in <module> import re, operator ImportError: /home/dropbox/.dropbox-dist/operator.so: undefined symbol: _PyUnicodeUCS2_AsDefaultEncodedString I'm running the current RHEL build of Python 2.6: root@cedar [/home/dropbox/.dropbox-dist]# rpm -qv python python-2.6.6-29.el6_3.3.x86_64 (I'm not sure if this would be better suited to Stack Overflow since it is on the verge of being a programming issue, but since I'm trying to use a program straight from Dropbox, I placed it here.)

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• use local ip and maintain ssl warning free [duplicate]

  - by Timothy Clemans

  This question already has an answer here: Loopback to forwarded Public IP address from local network - Hairpin NAT 6 answers I have a public facing website for a doctor's office for accessing the medical record. I'm using SSL. The server is at the doctor's office. When I access the website on the same network as the server I want the DNS to point to the local IP address. I don't want to do a HTTP redirect to the local ip because of the scary SSL warning. What's the recommended way of doing this?

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• Stale statistics on a newly created temporary table in a stored procedure can lead to poor performance

  - by sqlworkshops

  When you create a temporary table you expect a new table with no past history (statistics based on past existence), this is not true if you have less than 6 updates to the temporary table. This might lead to poor performance of queries which are sensitive to the content of temporary tables.I was optimizing SQL Server Performance at one of my customers who provides search functionality on their website. They use stored procedure with temporary table for the search. The performance of the search depended on who searched what in the past, option (recompile) by itself had no effect. Sometimes a simple search led to timeout because of non-optimal plan usage due to this behavior. This is not a plan caching issue rather temporary table statistics caching issue, which was part of the temporary object caching feature that was introduced in SQL Server 2005 and is also present in SQL Server 2008 and SQL Server 2012. In this customer case we implemented a workaround to avoid this issue (see below for example for workarounds).When temporary tables are cached, the statistics are not newly created rather cached from the past and updated based on automatic update statistics threshold. Caching temporary tables/objects is good for performance, but caching stale statistics from the past is not optimal.We can work around this issue by disabling temporary table caching by explicitly executing a DDL statement on the temporary table. One possibility is to execute an alter table statement, but this can lead to duplicate constraint name error on concurrent stored procedure execution. The other way to work around this is to create an index.I think there might be many customers in such a situation without knowing that stale statistics are being cached along with temporary table leading to poor performance.Ideal solution is to have more aggressive statistics update when the temporary table has less number of rows when temporary table caching is used. I will open a connect item to report this issue.Meanwhile you can mitigate the issue by creating an index on the temporary table. You can monitor active temporary tables using Windows Server Performance Monitor counter: SQL Server: General Statistics->Active Temp Tables. The script to understand the issue and the workaround is listed below:set nocount onset statistics time offset statistics io offdrop table tab7gocreate table tab7 (c1 int primary key clustered, c2 int, c3 char(200))gocreate index test on tab7(c2, c1, c3)gobegin trandeclare @i intset @i = 1while @i <= 50000begininsert into tab7 values (@i, 1, ‘a’)set @i = @i + 1endcommit trangoinsert into tab7 values (50001, 1, ‘a’)gocheckpointgodrop proc test_slowgocreate proc test_slow @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)endgodbcc dropcleanbuffersset statistics time onset statistics io ongo–high reads as expected for parameter ’1'exec test_slow 1godbcc dropcleanbuffersgo–high reads that are not expected for parameter ’2'exec test_slow 2godrop proc test_with_recompilegocreate proc test_with_recompile @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)option (recompile)endgodbcc dropcleanbuffersset statistics time onset statistics io ongo–high reads as expected for parameter ’1'exec test_with_recompile 1godbcc dropcleanbuffersgo–high reads that are not expected for parameter ’2'–low reads on 3rd execution as expected for parameter ’2'exec test_with_recompile 2godrop proc test_with_alter_table_recompilegocreate proc test_with_alter_table_recompile @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)–to avoid caching of temporary tables one can create a constraint–but this might lead to duplicate constraint name error on concurrent usagealter table #temp1 add constraint test123 unique(c1)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)option (recompile)endgodbcc dropcleanbuffersset statistics time onset statistics io ongo–high reads as expected for parameter ’1'exec test_with_alter_table_recompile 1godbcc dropcleanbuffersgo–low reads as expected for parameter ’2'exec test_with_alter_table_recompile 2godrop proc test_with_index_recompilegocreate proc test_with_index_recompile @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)–to avoid caching of temporary tables one can create an indexcreate index test on #temp1(c1)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)option (recompile)endgoset statistics time onset statistics io ondbcc dropcleanbuffersgo–high reads as expected for parameter ’1'exec test_with_index_recompile 1godbcc dropcleanbuffersgo–low reads as expected for parameter ’2'exec test_with_index_recompile 2go

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• Pantech Link II, Ubuntu and Virtual XP

  - by user85041

  Okay this is my problem. I have a Pantech Link II, dmesg states: [ 896.072037] usb 2-3: new high-speed USB device number 3 using ehci_hcd [ 896.258562] cdc_acm 2-3:1.0: ttyACM0: USB ACM device [ 896.260039] usbcore: registered new interface driver cdc_acm [ 896.260042] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters Have it installed through wine (pc suite and driver) and it doesn't see it. Virtual XP through VMWare Player sees my device, knows it needs a driver. The removable devices says Curitel Pantech USB Device (Maybe Driver). I have PC Suite installed in XP, I install the driver through the executable.. it says problem with installing hardware, and then it disappears. Ubuntu sees it after restart, but if I start XP with that driver installed, it disappears from both and I get these errors in dmesg: [ 1047.760555] /dev/vmmon[2882]: PTSC: initialized at 3093322000 Hz using TSC, TSCs are synchronized. [ 1048.174033] /dev/vmmon[2882]: Monitor IPI vector: 0 [ 1055.293060] /dev/vmnet: open called by PID 3163 (vmx-vcpu-0) [ 1055.293074] /dev/vmnet: port on hub 8 successfully opened [ 1055.293088] /dev/vmnet: open called by PID 3163 (vmx-vcpu-0) [ 1055.293094] /dev/vmnet: port on hub 8 successfully opened [ 1072.446305] /dev/vmnet: open called by PID 3163 (vmx-vcpu-0) [ 1072.446316] /dev/vmnet: port on hub 8 successfully opened [ 1072.446328] /dev/vmnet: open called by PID 3163 (vmx-vcpu-0) [ 1072.446334] /dev/vmnet: port on hub 8 successfully opened [ 1072.856024] usb 1-1: reset high-speed USB device number 2 using ehci_hcd [ 1079.292024] usb 1-1: reset high-speed USB device number 2 using ehci_hcd [ 1079.732024] usb 1-1: reset high-speed USB device number 2 using ehci_hcd [ 1127.743034] NET: Registered protocol family 39 [ 1127.749320] [3163]: VMCI: IOCTL_VMCI_QUEUEPAIR_ALLOC (cid=1522210225,result=4). [ 1144.104031] usb 2-3: reset high-speed USB device number 3 using ehci_hcd [ 1144.412031] usb 2-3: reset high-speed USB device number 3 using ehci_hcd [ 1155.889976] ehci_hcd 0000:00:13.2: force halt; handshake ffffc90000642024 00004000 00000000 -> -110 [ 1155.889980] ehci_hcd 0000:00:13.2: HC died; cleaning up [ 1155.890008] usb 2-3: USB disconnect, device number 3 [ 1155.890013] usb 2-3: usbfs: usb_submit_urb returned -110 [ 1658.310777] [3163]: VMCI: IOCTL_VMCI_QUEUEPAIR_DETACH (cid=1522210225,result=3). [ 1658.392018] NET: Unregistered protocol family 39 [ 1666.546438] /dev/vmnet: open called by PID 3163 (vmx-vcpu-0) [ 1666.546450] /dev/vmnet: port on hub 8 successfully opened [ 1666.546462] /dev/vmnet: open called by PID 3163 (vmx-vcpu-0) [ 1666.546467] /dev/vmnet: port on hub 8 successfully opened [ 1671.431383] uvcvideo: Found UVC 1.00 device USB2.0 Camera (1871:0101) [ 1671.432533] input: USB2.0 Camera as /devices/pci0000:00/0000:00:12.2/usb1/1-1/1-1:1.0/input/input13 lessa@X:~$ dmesg|tail [ 1155.890008] usb 2-3: USB disconnect, device number 3 [ 1155.890013] usb 2-3: usbfs: usb_submit_urb returned -110 [ 1658.310777] [3163]: VMCI: IOCTL_VMCI_QUEUEPAIR_DETACH (cid=1522210225,result=3). [ 1658.392018] NET: Unregistered protocol family 39 [ 1666.546438] /dev/vmnet: open called by PID 3163 (vmx-vcpu-0) [ 1666.546450] /dev/vmnet: port on hub 8 successfully opened [ 1666.546462] /dev/vmnet: open called by PID 3163 (vmx-vcpu-0) [ 1666.546467] /dev/vmnet: port on hub 8 successfully opened [ 1671.431383] uvcvideo: Found UVC 1.00 device USB2.0 Camera (1871:0101) [ 1671.432533] input: USB2.0 Camera as /devices/pci0000:00/0000:00:12.2/usb1/1-1/1-1:1.0/input/input13 I have tried uninstalling, and installing manually from the device manager update driver while it's still has the warning sign.. it doesn't see the drivers as valid. No idea how to fix this.. would prefer to not have to go to another computer. I'm not trying to do anything but get the pictures off of it. I have to restart ubuntu, plug in device, for ubuntu to see it correctly again. I am like a month and a half old linux newbie so I have no idea the commands I could use for this, and I don't have a memory card in the phone to mount.

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