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• H1 Visa interview tips–What you must know before attending the interview?

  - by Gopinath

  USA’s H1 visa allows highly qualified professionals from other countries to work in America. Many IT professionals in India aspire to go to USA on H1 and work for their clients. Recently I had a chance to study H1 visa process to help one of my friends and I would like to share what I learned. With the assumption that your H1 petition is approved and you got an interview scheduled at US Embassy for your visa stamping, here are tips you must know before attending the interview Dress Code – Formals Say no to casuals or any fancy dress when you attend the interview. It’s not a party or friends home you are visiting. Consider H1 Visa interview as your job interview and dress up in formals. There is no option B for your, you must be in formals. A plain formal shirt with a matching pant is suggested for men. Tie and Suit would not be required, but if you are a professional at management level you can consider wearing suit. Women can wear either formal Salwar or formal pant-shirt. Avoid heavy jewellery, wear what is must as per your tradition or culture. Body Language -  Smile on your face Your body language reflects what you are and what’s going on in your mind. Don’t be nervous or restless, be relaxed and wear a beautiful smile on your face. A smile is a curve that sets everything straight. When you are called for the interview, greet the interviewer with a beautiful smile. Say Good Morning/Afternoon/Evening depending on time you are visiting them. Whenever appropriate say Thank You. Generally American professionals are very friendly people and they reciprocate for your greetings. Make sure that you make them comfortable to start the interview. Carry original documents in a separate folder I don’t want to talk much about the documents that are required for your H1B interview as it’s big subject on it’s own and it requires a separate post. I assume that your consultant or employer helped you in gathering all the required documents like – petition, DS 160 forms, education & job related documents, resume, interview call letters, client letters, etc. For all the documents you are going to submit at the interview make sure that you have originals in a separate folder.  If required interviewer may ask you show the originals of any of the document you submitted for visa processing. Don’t mix the original documents with the documents you need to submit for interview. Have a separate folder for them. For those who are going to stamping along with their spouse and children, they need to carry few extra original documents like – marriage certificate, marriage photos(30 numbers)/album, birth certificates, passports, education and profession related certificates of the spouse and children. Know your role & responsibilities The interviewer will ask you questions on your roles and responsibilities at client location. Be clear what is your day to day tasks at client place and prepared to face detailed questions on the same. When asked explain clearly and also make sure what you say is inline with what is mentioned in your petition and client invitation letter. At times they may ask you questions specific to the project/technology you are going to work. So doing some homework in this area will help you easily answer the questions. Failing to answer basic questions on your role & responsibilities may result in rejection. You work for your Employer at Client location but NOT FOR CLIENT One of the important things to keep in mind that you work for your employer and you are being deputed to client location on a work visa.  Your employer is going to be solely responsible for your salary, work, promotion, pay hikes or what so ever during your stay at USA. Your client will not be responsible for anything. Lets say you are employed with Company X in India and they are applying for H1B to work at your client(ex: Microsoft) in USA, you must keep in my mind that Microsoft is not your employer. Microsoft will not pay your salaries or responsible for any employment related activities. Company X will be solely responsible for all your employer related activities. If you don’t get this correctly and say to Visa interviewer that your client is responsible, then you may get into troubles. Know your client It’s always good to know the clients with whom you are going to work in USA and their business. If your client is a well know organisation then you may not get many questions from interviewer else you need to be well prepared to provide details like – nature of business, location, size of the organisation, etc.  Get to know the basic details about your client and be confident while providing those details to the interviewer. Also make sure that you never talk about any confidential details of your client projects and business. Revealing confidential details of your client may land your job itself in soup. Make sure that your spouse is also in sync with you If you’ve applied a H4 visa for your spouse along with your H1, make sure that spouse is in sync with you. Your spouse also should know the basic details of your job, your employer, client and location where you will be travelling. Your spouse should also be prepared to answers questions related to marriage, their profession(if working), kids, education, etc. Interviewers will try to asses your spouse communication skills, whereabouts while staying in USA and would they prefer to work USA or not. On H4, which is a dependent visa, your spouse is not allowed to work in USA and at any point your spouse should not show the intentions to search for work in USA. Less luggage more comfort You would have definitely heard that there are lot of restrictions on what you can carry along with you to an US Embassy while attending the interview. To be frank it’s not good to say there are many restrictions, but there are a hell a lot of restrictions. There are unbelievable restrictions and it’s for the safety of everyone. You are not allowed to carry mobile phones, CD/DVDs, USBs, bank cards, cameras, cosmetics, food(except baby food), water, wallets, backpacks, sealed covers, etc. Trust me most of the things we carry with us regularly every day are not allowed inside. As there are 100s of restrictions, it would be easier if you understand what you can carry along with you and just carry them alone. Ask your employer/consultant to provide you a checklist of items that you can carry. Most what you would require are H1B related documents provided by the employer/consultant Photographs All original documents supporting your H1B Passports Some cash for your travel expenses (avoid coins) Any important phone number / details written in a paper(like your cab driver number, etc.) If you carry restricted stuff then you will be stopped at security checks, you have to find people who can safely keep all the restricted items. Due to heavy restrictions in and around the US Embassy you will not find any  place to keep your luggage. So just carry the bare minimum things required so that you feel more comfortable. Useful Links THE U.S. NON IMMIGRANT VISA APPLICATION PROCESS U.S VISA SECURITY REGULATIONS GENERAL FAQS Hope this information is helpful to you and best of luck for your interview. Creative commons Image credit: Flickr/ alexfrance, vinothchandar. hughelectronic, architratan, striatic

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• C#/.NET Little Wonders: Interlocked Read() and Exchange()

  - by James Michael Hare

  Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Last time we discussed the Interlocked class and its Add(), Increment(), and Decrement() methods which are all useful for updating a value atomically by adding (or subtracting).  However, this begs the question of how do we set and read those values atomically as well? Read() – Read a value atomically Let’s begin by examining the following code: 1: public class Incrementor 2: { 3: private long _value = 0; 4:  5: public long Value { get { return _value; } } 6:  7: public void Increment() 8: { 9: Interlocked.Increment(ref _value); 10: } 11: } 12:  It uses an interlocked increment, as we discuss in my previous post (here), so we know that the increment will be thread-safe.  But, to realize what’s potentially wrong we have to know a bit about how atomic reads are in 32 bit and 64 bit .NET environments. When you are dealing with an item smaller or equal to the system word size (such as an int on a 32 bit system or a long on a 64 bit system) then the read is generally atomic, because it can grab all of the bits needed at once.  However, when dealing with something larger than the system word size (reading a long on a 32 bit system for example), it cannot grab the whole value at once, which can lead to some problems since this read isn’t atomic. For example, this means that on a 32 bit system we may read one half of the long before another thread increments the value, and the other half of it after the increment.  To protect us from reading an invalid value in this manner, we can do an Interlocked.Read() to force the read to be atomic (of course, you’d want to make sure any writes or increments are atomic also): 1: public class Incrementor 2: { 3: private long _value = 0; 4:  5: public long Value 6: { 7: get { return Interlocked.Read(ref _value); } 8: } 9:  10: public void Increment() 11: { 12: Interlocked.Increment(ref _value); 13: } 14: } Now we are guaranteed that we will read the 64 bit value atomically on a 32 bit system, thus ensuring our thread safety (assuming all other reads, writes, increments, etc. are likewise protected).  Note that as stated before, and according to the MSDN (here), it isn’t strictly necessary to use Interlocked.Read() for reading 64 bit values on 64 bit systems, but for those still working in 32 bit environments, it comes in handy when dealing with long atomically. Exchange() – Exchanges two values atomically Exchange() lets us store a new value in the given location (the ref parameter) and return the old value as a result. So just as Read() allows us to read atomically, one use of Exchange() is to write values atomically.  For example, if we wanted to add a Reset() method to our Incrementor, we could do something like this: 1: public void Reset() 2: { 3: _value = 0; 4: } But the assignment wouldn’t be atomic on 32 bit systems, since the word size is 32 bits and the variable is a long (64 bits).  Thus our assignment could have only set half the value when a threaded read or increment happens, which would put us in a bad state. So instead, we could write Reset() like this: 1: public void Reset() 2: { 3: Interlocked.Exchange(ref _value, 0); 4: } And we’d be safe again on a 32 bit system. But this isn’t the only reason Exchange() is valuable.  The key comes in realizing that Exchange() doesn’t just set a new value, it returns the old as well in an atomic step.  Hence the name “exchange”: you are swapping the value to set with the stored value. So why would we want to do this?  Well, anytime you want to set a value and take action based on the previous value.  An example of this might be a scheme where you have several tasks, and during every so often, each of the tasks may nominate themselves to do some administrative chore.  Perhaps you don’t want to make this thread dedicated for whatever reason, but want to be robust enough to let any of the threads that isn’t currently occupied nominate itself for the job.  An easy and lightweight way to do this would be to have a long representing whether someone has acquired the “election” or not.  So a 0 would indicate no one has been elected and 1 would indicate someone has been elected. We could then base our nomination strategy as follows: every so often, a thread will attempt an Interlocked.Exchange() on the long and with a value of 1.  The first thread to do so will set it to a 1 and return back the old value of 0.  We can use this to show that they were the first to nominate and be chosen are thus “in charge”.  Anyone who nominates after that will attempt the same Exchange() but will get back a value of 1, which indicates that someone already had set it to a 1 before them, thus they are not elected. Then, the only other step we need take is to remember to release the election flag once the elected thread accomplishes its task, which we’d do by setting the value back to 0.  In this way, the next thread to nominate with Exchange() will get back the 0 letting them know they are the new elected nominee. Such code might look like this: 1: public class Nominator 2: { 3: private long _nomination = 0; 4: public bool Elect() 5: { 6: return Interlocked.Exchange(ref _nomination, 1) == 0; 7: } 8: public bool Release() 9: { 10: return Interlocked.Exchange(ref _nomination, 0) == 1; 11: } 12: } There’s many ways to do this, of course, but you get the idea.  Running 5 threads doing some “sleep” work might look like this: 1: var nominator = new Nominator(); 2: var random = new Random(); 3: Parallel.For(0, 5, i => 4: { 5:  6: for (int j = 0; j < _iterations; ++j) 7: { 8: if (nominator.Elect()) 9: { 10: // elected 11: Console.WriteLine("Elected nominee " + i); 12: Thread.Sleep(random.Next(100, 5000)); 13: nominator.Release(); 14: } 15: else 16: { 17: // not elected 18: Console.WriteLine("Did not elect nominee " + i); 19: } 20: // sleep before check again 21: Thread.Sleep(1000); 22: } 23: }); And would spit out results like: 1: Elected nominee 0 2: Did not elect nominee 2 3: Did not elect nominee 1 4: Did not elect nominee 4 5: Did not elect nominee 3 6: Did not elect nominee 3 7: Did not elect nominee 1 8: Did not elect nominee 2 9: Did not elect nominee 4 10: Elected nominee 3 11: Did not elect nominee 2 12: Did not elect nominee 1 13: Did not elect nominee 4 14: Elected nominee 0 15: Did not elect nominee 2 16: Did not elect nominee 4 17: ... Another nice thing about the Interlocked.Exchange() is it can be used to thread-safely set pretty much anything 64 bits or less in size including references, pointers (in unsafe mode), floats, doubles, etc.  Summary So, now we’ve seen two more things we can do with Interlocked: reading and exchanging a value atomically.  Read() and Exchange() are especially valuable for reading/writing 64 bit values atomically in a 32 bit system.  Exchange() has value even beyond simply atomic writes by using the Exchange() to your advantage, since it reads and set the value atomically, which allows you to do lightweight nomination systems. There’s still a few more goodies in the Interlocked class which we’ll explore next time! Technorati Tags: C#,CSharp,.NET,Little Wonders,Interlocked

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• backup and restoration of a freeipa infrastructure

  - by Sirex

  I'm finding the documentation on ipa server backup and restoration sadly lacking, and being so centrally critical it's not something i'm really happy about shooting in the dark with - could some kind soul more knowledable in the matter please attempt to provide an idiot-proof guide to backing up and restoring of IPA server(s) ? Particularly the main server (the cert signing one). ...We're looking towards rolling out ipa in a two server setup (1 master, 1 replica). I'm using dns srv records to handle failover, hence a loss of the replica isn't a big deal as i could make a new one and force a resync to happen - it's losing the master that bothered me. The thing that i'm really struggling with is locating a step-by-step procedure for backing up and restoring the master server. I'm aware that whole-VM snapshot is the recommended way of doing IPA server backup, but that isn't an option at this time for us. I'm also aware that freeipa 3.2.0 includes some sort of backup command build in, but that isn't in the ipa version of centos, and i don't expect it will be for some time yet. I've been trying many different methods, but none of them seem to restore cleanly, amongst others, i've tried; a command similar to db2ldif.pl -D "cn=directory manager" -w - -n userroot -a /root/userroot.ldif the script from here to produce three ldif files -- one for the domain ({domain}-userroot), and two for the ipa server (ipa-ipaca and ipa-userroot): Most of the restores i've tried have been similar to the form of: ldif2db.pl -D "cn=directory manager" -w - -n userroot -i userroot.ldif which seems to work and reports no errors, but totally borks the ipa install on the machine and i can no longer login with either the admin password on the backed up server, or the one i set it to on installation before attempting the ldif2db command (i'm installing ipa-server and running ipa-server-install, then attempting the restore). I'm not overly bothered about losing the CA, having to rejoin the domain, losing replication etc etc (although it'd be awesome if that could be avoided) but in the instance of the main server dropping i'd really like to avoid having to re-enter all the user/group information. I guess in the instance of losing the main server i could promote the other one and replicate in the other direction, but i've not tried that, either. Has anyone done that ? tl;dr: Can someone provide an idiots guide to backing up and restoring an IPA server (preferably on CentOS 6) in a clear enough way that'd make me feel confident it'll actually work when the dreaded time comes ? Crayons are optional, but appreciated ;-) I can't be the only person struggling with this, seeing how widely used IPA is, surely ?

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• Linux Mint 14 severe overheating

  - by agvares

  I've tried switching to Mint (it was Mint 12) about 6 months ago, but failed to do it due to enormous overheating which made it virtually impossible to run any applications more complex than Gedit. Time had passed, and now I'm back again with Mint 14, but feeling way more determined. What I face are the following issues: 1) Great overheating (and by great I mean that just by doing nothing my CPU temp is floating around 70-75 C, which I find a lot) 2) Running multiple applications (let's say Chrome, Skype and Pidgin) results in critical overheating and immediate shutdown of the system 3) Due to the stuff listed above, my battery drains in about 10-15 minutes, pretty much turning my laptop into a crippled desktop machine I've got a HP-dv6 laptop (i7, 6gb RAM, dual graphics) Here's the output of lspci: 00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09) 00:01.0 PCI bridge: Intel Corporation Xeon E3-1200/2nd Generation Core Processor Family PCI Express Root Port (rev 09) 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) 00:16.0 Communication controller: Intel Corporation 6 Series/C200 Series Chipset Family MEI Controller #1 (rev 04) 00:1a.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #2 (rev 05) 00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 05) 00:1c.0 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 1 (rev b5) 00:1c.1 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 2 (rev b5) 00:1c.2 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 3 (rev b5) 00:1c.3 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 4 (rev b5) 00:1d.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1 (rev 05) 00:1f.0 ISA bridge: Intel Corporation HM65 Express Chipset Family LPC Controller (rev 05) 00:1f.2 SATA controller: Intel Corporation 6 Series/C200 Series Chipset Family 6 port SATA AHCI Controller (rev 05) 00:1f.3 SMBus: Intel Corporation 6 Series/C200 Series Chipset Family SMBus Controller (rev 05) 01:00.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI Whistler XT [AMD Radeon HD 6700M Series] 07:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 06) 0d:00.0 Network controller: Broadcom Corporation BCM4313 802.11b/g/n Wireless LAN Controller (rev 01) 13:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS5209 PCI Express Card Reader (rev 01) 19:00.0 USB controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 04) what i've tried to do already: 1) I've edited my grub file to add some "splash" arguments there 2) Installed jupiter and powertop 3) Tried to upgrade to newer kernels (up to 3.8), btw running anything newer than 3.5 results in both resolution and wi-fi detection fail 4) Read lots of forum threads devoted to the topic So, my question is simple: What else might I do to become finally able to use Mint as my default OS without the risk of being burned alive by the CPU heat?

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• Gateway GT5220 Boot/POST Failure

  - by John Rudy

  I have a Gateway GT5220 I'm troubleshooting. It is, in fact, the machine I just gave my father for his birthday a couple months ago. (Prior to that, it was my home PC. My home PC is now the MacBook on which I'm writing this.) Before going any further, I suspect that the answer will be, "It's worse than that, it's dead, Jim, it's dead, Jim, it's dead, Jim." At least, mobo and/or CPU. The initial symptoms were as follows: Turn on power All fans fire up (thus making it so I can't hear if the hard drive is spinning or not, nor are my hands sensitive enough anymore to feel it) No LEDs remained lit on the front panel. (Initially, the hard drive indicator flashed briefly.) No beep, no video, no nothing. Following some advice I found here, I tried to "drain the stored power." After following those steps, the new symptoms were: Turn on power All fans fire up The front panel LEDs remained lit! After about 20, maybe 30 seconds, we had video! Sort of. We got to the Gateway splash/POST screen, which appeared thoroughly corrupted. How corrupted? Well, I imagine it's what a POST screen would look like after reading the wrong passage out of the Necronomicon: It stayed there. I gave it at least 5, maybe 6 minutes, and it didn't move. So I shut her down, started her up again, and now (this is where we currently stand, symptomatically) we have this: Turn on power All fans fire up The front panel LEDs remain lit No video, no beep, no nothing. I'm a software guy; haven't done real hardware troubleshooting in years. My gut tells me that the mobo and/or CPU is fried, and unfortunately my gut didn't get to be as big as it is being wrong all the time. :( In addition to the link above, I have read all of the following (trying to save you some LMGTFY trouble): Gateway Support POST Error Messages and Handling About a zillion (useless) POST beep code sites A kioskea.net post indicating that most likely we're at what I consider "total loss" (mobo and/or CPU) My questions: Are there any conditions other than mobo/CPU that could cause symptoms like these? Is it worth my time to try the next hardware troubleshooting step?(IE, remove all non-critical hardware from the machine, try to boot, systematically replace one by one until we find the failing component) Which mobos will fit in the Gateway GT5220 case (with rear ports correctly aligned)? (Why this is not a dupe: I wouldn't have posted this question if it hadn't been for the funkadelic possessed video display on the one occasion we got video out. I think that justified this not being an exact dupe. Of course, if the community overrules, I will understand.)

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• What "pieces" are needed in order to set up a cluster of physical servers?

  - by Chris Dutrow

  Background: Currently, we use Rackspace cloud servers. We have no intention to stop using them, but would like to look into setting up a cluster of physical servers (probably desktop computers in the $400 range with 8gb memory each) to offset some of our load and work as a secondary, more powerful, less reliable system. To put things in perspective, we can buy comparable desktop computers for the same price as we pay in one month to rent them on Rackspace Cloud. I understand that this is generally a dumb idea. However, in this particular instance, the server cluster is needed for its computation power. It is not mission-critical, it does not host a consumer-facing website, and if it goes down for a day or two, its not really a problem. Currently, we have access to business class verizon fios. If I understand correctly, we can get at least 25 dedicated IP addresses with this service, this should be enough. Requirements: Each server runs Linux Centos 6.3 Some of the servers run Python and execute processes from a task queue (Redis or RabbitMQ) Some of the servers are capable of serving static files and Python driven REST APIs Some of the servers host a Cassandra database cluster One or more of the servers are a Redis database servers One or more of the servers are PostgreSQL servers Questions: What kind of router or switch is needed? We would like the computers to be able to communicate effectively with each other via internal IP addresses. This is especially important for communicating with servers hosting Redis that need to be able to respond to requests very quickly. Are there special switches or routers that need to be used to connect the servers together? Are Desktop computers ok for this? We have found that we are mostly RAM-bottle necked, I understand that some servers have highly superior CPUs, but I'm not sure we need CPU power as much as we need RAM, which is cheap in Desktop computers. Will we have problems with the WIFI cards in the desktops or any other unexpected hardware limitation? What tools should be used to "image" the servers. For example, when we get an installation right for a Redis server or Cassandra node, are there tools that come with Linux Centos 6.3 to image the server to a USB drive or something like that? Or do we need to use some other software for this? What other things are we missing that we should be concerned about? Thanks so much!

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• The Koyal Group Info Mag News¦Charged building material could make the renewable grid a reality

  - by Chyler Tilton

  What if your cell phone didn’t come with a battery? Imagine, instead, if the material from which your phone was built was a battery. The promise of strong load-bearing materials that can also work as batteries represents something of a holy grail for engineers. And in a letter published online in Nano Letters last week, a team of researchers from Vanderbilt University describes what it says is a breakthrough in turning that dream into an electrocharged reality. The researchers etched nanopores into silicon layers, which were infused with a polyethylene oxide-ionic liquid composite and coated with an atomically thin layer of carbon. In doing so, they created small but strong supercapacitor battery systems, which stored electricity in a solid electrolyte, instead of using corrosive chemical liquids found in traditional batteries. These supercapacitors could store and release about 98 percent of the energy that was used to charge them, and they held onto their charges even as they were squashed and stretched at pressures up to 44 pounds per square inch. Small pieces of them were even strong enough to hang a laptop from—a big, fat Dell, no less. Although the supercapacitors resemble small charcoal wafers, they could theoretically be molded into just about any shape, including a cell phone’s casing or the chassis of a sedan. They could also be charged—and evacuated of their charge—in less time than is the case for traditional batteries. “We’ve demonstrated, for the first time, the simple proof-of-concept that this can be done,” says Cary Pint, an assistant professor in the university’s mechanical engineering department and one of the authors of the new paper. “Now we can extend this to all kinds of different materials systems to make practical composites with materials specifically tailored to a host of different types of applications. We see this as being just the tip of a very massive iceberg.” Pint says potential applications for such materials would go well beyond “neat tech gadgets,” eventually becoming a “transformational technology” in everything from rocket ships to sedans to home building materials. “These types of systems could range in size from electric powered aircraft all the way down to little tiny flying robots, where adding an extra on-board battery inhibits the potential capability of the system,” Pint says. And they could help the world shift to the intermittencies of renewable energy power grids, where powerful batteries are needed to help keep the lights on when the sun is down or when the wind is not blowing. “Using the materials that make up a home as the native platform for energy storage to complement intermittent resources could also open the door to improve the prospects for solar energy on the U.S. grid,” Pint says. “I personally believe that these types of multifunctional materials are critical to a sustainable electric grid system that integrates solar energy as a key power source.”

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• Safer RAID5 rebuilds using partially failed disks?

  - by arcticmac

  There have been lots of articles posted recently about how RAID5 is dangerous because of long resilver times, and in particular because of increasing chances of encountering a URE during the resilver. Obviously this is a significant concern. However, it seems that in many cases of interest (as long as you're keeping some kind of eye on your disks), when it comes time to rebuild the array, the disk that I'm replacing is still mostly readable. If you try to explain this predicament to the average layperson, they are typically very confused as to why you have two almost completely functional disks but can't produce one working array. It seems to me that there ought to be some way to take advantage of this to make rebuilds safer, as long as I'm willing to have the RAID5 be read-only for a couple of days while it rebuilds. Conceptually, what I have in mind looks something like this: When a disk fails, immediately take the RAID5 offline or mount it read-only Attach a new disk (either in a spare bay, or externally via eSATA) and begin rebuilding it to replace the failed one. If known, perhaps start with the stripes in which the failure occurred, to minimize the chances of losing those if another disk fails. In the event that a second disk experiences a URE or other failure during the rebuild, try to source that data from the disk that is being replaced. Presumably if this happens, more rebuilding would be necessary. When complete, shut down the server, swap the replacement drive into the original bay if desired, and bring the array back up. Obviously such a process would not be appropriate for applications where uptime is critical or data loss cannot be tolerated, but it seems to me that this could help considerably to improve the reliability of RAID5. I assume that there's not a good way to implement a recovery like this at present, given that I haven't seen any indication of tools that are designed to do this, and that it seems like it would be rather obtuse to work out manually. Are there also technical issues with it that I haven't thought of (I'm still fairly new to RAID stuff)? Any thoughts on how hard something like this would be to implement (e.g. in linux md raid)?

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• Intermittent Disconnection of Client Computers from Domain Server

  - by dilip nagle

  The Background: I have Windows 2008 server Enterprise Version with 25 user cal licences. It has a domain and all users and a network shared HP printer in it. The Server has two network cards and both these cards as well as all client machines are on IP addressing scheme of 192.168.1.* with subnetmask 255.255.255.0. Of the two network cards viz. 192.168.1.231 and 192.168.1.233, only 192.168.1.231 is registered with DNS. In 192.168.1.233(i.e. 2nd network card) has default getway as 192.168.1.231 and dns address as 192.168.1.231. The Server has three hard disks with capacities as 500gb, 500gb and 1TB and are partitioned as (C,D,E), (F,G) and (K) with partition K having all user data into various Shared Folders. Each of these folders(On Partition K), are mapped onto each user's computer as per the right of access given to them. The Problem: The Server was installed about 6 months ago and till date not even once, the Server has Hung or has given any problem. All the Clients computers are able to run the web based software from their computers via ip address, e.g. http://192.168.1.231/webERP/default.aspx. However, occassionally, when any client computer tries to browse network mappings, it hangs. Again, there is no fixed pattern. This may happen after running smoothly for say 3 days. On each Client's machine, the network settings are as follows: IP Address: 192.168.1.* where * is 1,2,3 .... Sunnetmask: 255.255.255.0 defauly getway: 192.168.1.231 Which is a server card and DNS address. preferred DNS Server: 192.168.1.231 In Advanced Tab under Wins: LMHostLookup is Unticked and default is radio buttoned. Ideally, I would have loved to have Disabled NETBIOS over TCP/IP but some network printers do not get accessed if this option is enabled(ie. Radio Buttoned). Bacause Disabling Netbios will drastically reduce traffic of NETBIOS broadcasting to all the computers on the net to do naming resolution. On Server, I have WINs Running which I have Scavanged Records, verified Database Integrity etc, removed Tombstoned Records etc. The Critical Errors shown only once a day when the server is statred are 4224(WINS) and 12923 - Server Licencing failed to Update DNS Record. I fail to understand as why do client machines HANG when they try to browse mapped network shared folders on K Drive. Kindly Advice

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• Do RAID controllers commonly have SATA drive brand compatibility issues?

  - by Jeff Atwood

  We've struggled with the RAID controller in our database server, a Lenovo ThinkServer RD120. It is a rebranded Adaptec that Lenovo / IBM dubs the ServeRAID 8k. We have patched this ServeRAID 8k up to the very latest and greatest: RAID bios version RAID backplane bios version Windows Server 2008 driver This RAID controller has had multiple critical BIOS updates even in the short 4 month time we've owned it, and the change history is just.. well, scary. We've tried both write-back and write-through strategies on the logical RAID drives. We still get intermittent I/O errors under heavy disk activity. They are not common, but serious when they happen, as they cause SQL Server 2008 I/O timeouts and sometimes failure of SQL connection pools. We were at the end of our rope troubleshooting this problem. Short of hardcore stuff like replacing the entire server, or replacing the RAID hardware, we were getting desperate. When I first got the server, I had a problem where drive bay #6 wasn't recognized. Switching out hard drives to a different brand, strangely, fixed this -- and updating the RAID BIOS (for the first of many times) fixed it permanently, so I was able to use the original "incompatible" drive in bay 6. On a hunch, I began to assume that the Western Digital SATA hard drives I chose were somehow incompatible with the ServeRAID 8k controller. Buying 6 new hard drives was one of the cheaper options on the table, so I went for 6 Hitachi (aka IBM, aka Lenovo) hard drives under the theory that an IBM/Lenovo RAID controller is more likely to work with the drives it's typically sold with. Looks like that hunch paid off -- we've been through three of our heaviest load days (mon,tue,wed) without a single I/O error of any kind. Prior to this we regularly had at least one I/O "event" in this time frame. It sure looks like switching brands of hard drive has fixed our intermittent RAID I/O problems! While I understand that IBM/Lenovo probably tests their RAID controller exclusively with their own brand of hard drives, I'm disturbed that a RAID controller would have such subtle I/O problems with particular brands of hard drives. So my question is, is this sort of SATA drive incompatibility common with RAID controllers? Are there some brands of drives that work better than others, or are "validated" against particular RAID controller? I had sort of assumed that all commodity SATA hard drives were alike and would work reasonably well in any given RAID controller (of sufficient quality).

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• HP UX can not boot from Ignite Tape

  - by Spirit

  We have hp rp2470 server running hp-ux 11.00, with LVM mirroring. As for redundancy we have second rp2470 same hw (same two processors, same ram, same two hdd’s, same number of lan cards). I want to clone first one to the second. For that purpose I am making ignite tape with the following command: make_tape_recovery -x inc_entire=vg00 Ignite tape finishes without problems. When I boot second server from this ignate tape, server is starting to boot, and ignite restore finishes without any errors, only few notes, which are normal. However vmunix is not booting and when restore finishes, it boot to ISL prompt. From this I cannot boot /stand/vmunix. I tried to run recovery shell but no success. When recovery shell ask to do frecover to restore critical files, then I receive error: frecover(5405): unable to open /dev/rmt/0m At first I thought that the problem might be in the difference of the firmware version of the servers: fw version of production server is: Firmware Version 43.50 and fw version of backup server is: Firmware Version 42.19 So i did a fw upgrade of my backup server so that both servers are v43.50, and tried a recovery but again cant boot the system. Next I did another archive tape with -I (Interactive) flag: make_tape_recovery -I -x inc_entire=vg00 and tried recovery with it, again no good. I cannot find any error or warnings on ignite log, and I cannot boot hpux. I am only on ISL prompt. This is what i've noticed on the gsp logs: ************* SYSTEM ALERT ************** SYSTEM NAME: mcnfwim1 DATE: 07/27/2003 TIME: 10:18:49 ALERT LEVEL: 6 = Boot possible, pending failure - action required REASON FOR ALERT SOURCE: 8 = I/O SOURCE DETAIL: 6 = disk SOURCE ID: 0 PROBLEM DETAIL: 0 = no problem detail LEDs: RUN ATTENTION FAULT REMOTE POWER FLASH OFF ON ON ON LED State: Boot Failed. Running non-OS code. Check Chassis and Console Logs for error messages. 0x00000060860010B0 00000000 00000000 - type 0 = Data Field Unused 0x58000860860010B0 00006706 1B0A1231 - type 11 = Timestamp 07/27/2003 10:18:49 And another gsp log: Log Entry # 3 : SYSTEM NAME: mcnfwim1 DATE: 07/27/2003 TIME: 10:12:20 ALERT LEVEL: 6 = Boot possible, pending failure - action required SOURCE: 8 = I/O SOURCE DETAIL: 6 = disk SOURCE ID: 0 PROBLEM DETAIL: 0 = no problem detail CALLER ACTIVITY: 1 = test STATUS: 0 CALLER SUBACTIVITY: 0B = implementation dependent REPORTING ENTITY TYPE: 0 = system firmware REPORTING ENTITY ID: 00 0x00000060860010B0 00000000 00000000 type 0 = Data Field Unused 0x58000860860010B0 00006706 1B0A0C14 type 11 = Timestamp 07/27/2003 10:12:20 Type CR for next entry, - CR for previous entry, Q CR to quit. Please note that I can not change anything on the production server. I can only make changes to the backup server. Any help is appreciated.

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• Real-time offline folder-to-folder backup application needed (Windows)

  - by niktech

  I recently started using Intel Matrix Storage RAID solution that allowed me to use my 5 1TB drives for two RAID volumes. First one a 1TB RAID 0 striped across all 5 drives and second one a RAID 5 across the rest of the free space on all drives (around 2.85TB usable space). The RAID 0 I use for OS, applications and games while the RAID 5 I use as a more-permanent type storage (photos, etc). Now I do realize that running the OS and applications on RAID 0 across 5 drives is very dangerous, which is what brings up the following question. Is there a reliable freeware realtime backup application that can backup a set of folders from one drive to another drive (no online backups needed)? I've already tried a few (Mozy, Yadis, Comodo Backup, GFI Backup, Idoo, Crash Plan) but none meet my requirements: Low CPU and RAM usage. Realtime Backups - as soon as a file is modified in the source folder, it is added to the backup queue which will be processed with the lowest priority when the CPU is idle. This backup queue should persist in cases of computer restarts (ie: the source and destination folders should always have the same set of files, except for the ones waiting in the backup queue). Incremental Backups - if only 10 bytes changed in a 1GB file, the app should only copy those 10 new bytes. Ability to back up locked and opened files (some apps, like Yadis, can't back up critical files like browser favorites). Ability to run as a service (no need for any user to log-in to have the app started). Optional requirements: Compression of the destination into a well-known format (RAR, Zip) that can be directly read without the use of the application. Preset source folders (such as Browser Favorites, Game Saves, Application Settings, etc). The idea is to use RAID 0 array as "semi-persistent RAM-like" storage which in case of a failure can be quickly rebuilt by reinstalling the OS, apps and games and copying over the settings, saves, favorites from the RAID 5. I'm also thinking of taking this RAID 0 as RAM idea to the extreme with SSDs (as soon as we get some nice 6Gb/s SATA III SSDs out there), where a couple of SSDs chained in RAID 0 will work as yet another semi-persistent cache layer sitting between the RAM and the HD. I'm just hoping there already exists an application that satisfies these requirements... otherwise I'll have to write one myself, which I would prefer not to do.

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• configuration required for HIVE to be installed on a node

  - by ????? ????????

  I went through the process of manually installing ambari (not through SSH, because I couldnt get keyless to work) and everything installed OK, except for HIVE and GANGLIA. I got this message: stderr: None stdout: warning: Unrecognised escape sequence ‘\;’ in file /var/lib/ambari-agent/puppet/modules/hdp-hive/manifests/hive/service_check.pp at line 32 warning: Dynamic lookup of $configuration is deprecated. Support will be removed in Puppet 2.8. Use a fully-qualified variable name (e.g., $classname::variable) or parameterized classes. notice: /Stage[1]/Hdp::Snappy::Package/Hdp::Snappy::Package::Ln[32]/Hdp::Exec[hdp::snappy::package::ln 32]/Exec[hdp::snappy::package::ln 32]/returns: executed successfully notice: /Stage[2]/Hdp-hive::Hive::Service_check/File[/tmp/hiveserver2Smoke.sh]/ensure: defined content as ‘{md5}7f1d24221266a2330ec55ba620c015a9' notice: /Stage[2]/Hdp-hive::Hive::Service_check/File[/tmp/hiveserver2.sql]/ensure: defined content as ‘{md5}0c429dc9ae0867b5af74ef85b5530d84' notice: /Stage[2]/Hdp-hcat::Hcat::Service_check/File[/tmp/hcatSmoke.sh]/ensure: defined content as ‘{md5}bae7742f7083db968cb6b2bd208874cb’ notice: /Stage[2]/Hdp-hcat::Hcat::Service_check/Exec[hcatSmoke.sh prepare]/returns: 13/06/25 03:11:56 WARN conf.HiveConf: DEPRECATED: Configuration property hive.metastore.local no longer has any effect. Make sure to provide a valid value for hive.metastore.uris if you are connecting to a remote metastore. notice: /Stage[2]/Hdp-hcat::Hcat::Service_check/Exec[hcatSmoke.sh prepare]/returns: FAILED: SemanticException org.apache.hadoop.hive.ql.parse.SemanticException: org.apache.hadoop.hive.ql.metadata.HiveException: java.lang.RuntimeException: Unable to instantiate org.apache.hadoop.hive.metastore.HiveMetaStoreClient notice: /Stage[2]/Hdp-hcat::Hcat::Service_check/Exec[hcatSmoke.sh prepare]/returns: 13/06/25 03:12:06 WARN conf.HiveConf: DEPRECATED: Configuration property hive.metastore.local no longer has any effect. Make sure to provide a valid value for hive.metastore.uris if you are connecting to a remote metastore. notice: /Stage[2]/Hdp-hcat::Hcat::Service_check/Exec[hcatSmoke.sh prepare]/returns: FAILED: SemanticException [Error 10001]: Table not found hcatsmokeida8c07401_date102513 notice: /Stage[2]/Hdp-hcat::Hcat::Service_check/Exec[hcatSmoke.sh prepare]/returns: 13/06/25 03:12:15 WARN conf.HiveConf: DEPRECATED: Configuration property hive.metastore.local no longer has any effect. Make sure to provide a valid value for hive.metastore.uris if you are connecting to a remote metastore. notice: /Stage[2]/Hdp-hcat::Hcat::Service_check/Exec[hcatSmoke.sh prepare]/returns: FAILED: SemanticException o When i go to the alerts and health checks i’m getting this: ive Metastore status check CRIT for 42 minutes CRITICAL: Error accessing hive-metaserver status [13/06/25 03:44:06 WARN conf.HiveConf: DEPRECATED: Configuration property hive.metastore.local no longer has any effect. What am I doing wrong? I have already tried to do ambari-server reset on the the database without results.

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• VBA + Polymorphism: Override worksheet functions from 3rd party

  - by phi

  my company makes extensive use of a data provider using a (closed source) VBA plugin. In principal, every query follows follows a certain structure: Fill one cell with a formula, where arguments to the formula specify the query the range of that formula is extended (not an arrray formula!) and cells below/right are filled with data For this to work, however, a user has to have a terminal program installed on the machine, as well as a com-plugin referenced in VBA/Excel. My Problem These Excelsheets are used and extended by multiple users, and not all of them have access to the data provider. While they can open the sheet, it will recalculate and the data will be gone. However, frequent recalculation is required. I would like every user to be able to use the sheets, without executing a very specific set of formulas. Attempts remove the reference on those computers where I do not have terminal access. This generates a NAME error i the cell containing the query (acceptable), but this query overrides parts of the data (not acceptable) If you allow the program to refresh, all data will be gone after a failed query Replace all formulas with the plain-text result in the respective cells (press a button and loop over every cell...). Obviously destroys any refresh-capabilities the querys offer for all subsequent users, so pretty bad, too. A theoretical idea, and I'm not sure how to implement it: Replace the functions offered by the plugin with something that will be called either first (and relay the query through to the original function, if thats available) or instead of the original function (by only deploying the solution on non-terminal machines), which just returns the original value. More specifically, if my query function is used like this: =GETALLDATA(Startdate, Enddate, Stockticker, etc) I would like to transparently swap the function behind the call. Do you see any hope, or am I lost? I appreciate your help. PS: Of course I'm talking about Bloomberg... Some additional points to clarify issues raise by Frank: The formula in the sheets may not be changed. This is mission-critical software, and its way too complex for any sane person to try and touch it. Only excel and VBA may be used (which is the reason for the previous point...) It would be sufficient to prevent execution of these few specific formulas/functions on a specific machine for all excel sheets to come This looks more and more like a problem for stackoverflow ;-)

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• Radeon HD4850 serious issues when using DirectX 10

  - by ricsmania

  Hello, I have a problem with my video card. Whenever I run a DirectX 10 game, it works for a few seconds (10 or so) and then starts displaying nothing but big polygons. I have tested this with Crysis and Resident Evil 5, both have the same problems. The same games running under DirectX 9 work fine, except for some small black squares once in a while. I have the following specs: Asus P7P55D LE Intel Core i5 750 Sapphire Radeon HD4850 1GB 2x2GB Patriot Viper II Sector 5, DDR3 1600 MHz OCZ Stealth X Stream 500SXS 500W At first I thought it could be the video card overheating (it has stock cooling), but the game crashes even when it's running at 50 degrees C, and it's never been higher than 70. I also thought it could be the PSU, but as far as I know 500W is enough for this computer, especially because I haven't overclocked anything. My OS is Windows 7 X64 and I am using Catalyst 10.10, but I have also tried many older versions with no success. I don't think there is a problem with the card itself, or else it wouldn't run DirectX 9 games I believe. I have spent many hours searching for a solution but I couldn't, so any help is appreciated. Thank you. EDIT: I did some further investigation about the problem, and it seems taspeotis was right, it might be related to memory. I slightly underclocked the memory from 993 to 965 MHz and the problem went away completely. Both the black squares using DirectX 9 and the weird polygons using DirectX 10. I was using RE DirectX 10 Benchmark, as it consistently crashed around the same point, and now I can play the full benchmark with no artifacts at all. Unfortunately, the underclock has an obvious hit in performance. Although it's not critical, it's definitely noticeable. So, if the video memory test software showed no erros, but the card needs an underclock to work, what might be the problem? Temperature? Voltage? By the way, I couldn't find what the default voltage for this card is. And what is a good software to try and increase it? I tried Ati Tray Tools but it has a bug that increases the clock speed dramatically whenever I change something in the Overclock tab, so I'm afraid it might fry my card. Worst case scenario, if I don't find I solution I will try to slightly increase the GPU clock to compensate for the memory clock. Thank you again.

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• New Exchange 2010 CAS cannot find domain controllers

  - by NorbyTheGeek

  I am experiencing problems migrating from Exchange 2003 to Exchange 2010. I am on the first step: installing a new 2010 Client Access Server role. The Active Directory domain functional level is 2003. All domain controllers are 2003 R2. The only existing Exchange 2003 server happens to be housed on one of the domain controllers. It is running Exchange 2003 Standard w/ SP2. IPv6 is enabled and working on all domain controllers, servers, and routers, including this new Exchange server. After installing the CAS role on a new 2008 R2 server (Hyper-V VM) I am receiving 2114 Events: Process MSEXCHANGEADTOPOLOGYSERVICE.EXE (PID=1600). Topology discovery failed, error 0x80040a02 (DSC_E_NO_SUITABLE_CDC). Look up the Lightweight Directory Access Protocol (LDAP) error code specified in the event description. To do this, use Microsoft Knowledge Base article 218185, "Microsoft LDAP Error Codes." Use the information in that article to learn more about the cause and resolution to this error. Use the Ping or PathPing command-line tools to test network connectivity to local domain controllers. Prior to each, I receive the following 2080 Event: Process MSEXCHANGEADTOPOLOGYSERVICE.EXE (PID=1600). Exchange Active Directory Provider has discovered the following servers with the following characteristics: (Server name | Roles | Enabled | Reachability | Synchronized | GC capable | PDC | SACL right | Critical Data | Netlogon | OS Version) In-site: b.company.intranet CDG 1 0 0 1 0 0 0 0 0 s.company.intranet CDG 1 0 0 1 0 0 0 0 0 Out-of-site: a.company.intranet CD- 1 0 0 0 0 0 0 0 0 o.company.intranet CD- 1 0 0 0 0 0 0 0 0 g.company.intranet CD- 1 0 0 0 0 0 0 0 0 Connectivity between the new Exchange server and all domain controllers via IPv4 and IPv6 are all working. I have verified that the new Exchange server is a member of the following groups: Exchange Servers Exchange Domain Servers Exchange Install Domain Servers Exchange Trusted Subsystem Heck, I even put the new Exchange server into Domain Admins just to see if it would help. It didn't. I can't find any evidence of Active Directory replication problems, all pre-setup Setup tasks (/PrepareLegacyExchangePermissions, /PrepareSchema, /PrepareAD, /PrepareDomain) completed successfully. The only problem so far that I haven't been able to resolve with my Active Directory is I am unable to get my IPv6 subnets into Sites and Services Where should I proceed from here?

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• Vista stuck at "Shutting down..." screen. Any way to get verbose logging?

  - by CapBBeard

  Hi all, My home machine has been running fine for about 3 years, no problems at all. Within the last couple of weeks it's had real trouble trying to shut down. It'll get so far and then just sit there at the "Shutting down..." screen for hours. I've left it overnight, I've tried in safe mode, all to no avail. These days, I just wait for the disk activity to finish up and then hold the power button to turn it off. Feels dirty as, especially because there's a RAID involved! The hardware itself is in pretty good shape and of decent spec; Core 2 Quad, 4GB RAM, 1TB RAID 1+0, so it's not quite like a 7 year old PC coming to end of life! In the last month, hardware hasn't changed except for a new monitor. Admittedly I haven't tried unplugging the monitor but I've never heard of that preventing a shutdown. I might give it a whirl later I guess, as a last resort. I've uninstalled old apps, done updates, checked the event log, looked in device manager, uninstalled all non-present devices, disabled various non-critical devices (imaging, audio etc), unplugged peripherals, stopped non-essential services, unplugged the network, disabled the network adapter entirely, ran chkdsk, verified my RAID, the list goes on. But not a single lead. I'm pretty stumped. It could be hardware, but I have no other evidence to suggest so; when the PC is running, it runs fine. Temperatures are good, gaming is smooth as always, disk performance is fine. Event log even makes it look like the shutdown was completed (gets to the point where the event log service stops). In fact, the PC doesn't appear to realise that I cut the power to it. So my question is, does anyone know if there is a way I can get some verbose output (or a log) from shutdown to give me some idea of what is causing the issue? I'm guessing it's stuck unloading some app/driver but it would be good to get some specifics! Unless anyone has any other ideas? I suspect a reinstall would resolve the issue, however I'm looking to get a new PC built in the next month or so, and the reinstall is going to be quite a big job so I'd rather just wait until then if it comes to that. Would still be nice to get this sorted in the mean time though. Cheers!

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• Linux Software RAID1 Rebuild Completes, but after reboot, its degraded again

  - by zimmy6996

  I have been beating my head with an issue here, and I'm now turning to the internet for help. I have a system running Mandrake Linux, with the following configuration: /dev/hda - This is a IDE drive. Has some partitions on it that boot the system and make up most of the file system. /dev/sda - This is drive 1 of 2 for a software raid /dev/md0 /dev/sdb - This is drive 2 of 2 for a software raid /dev/md0 md0 gets mounted but fstab as /data-storage, so it is not critical to the systems ability to boot. We can comment it out of fstab, and the system works just fine either way. The problem is, we have a failed sdb drive. So I shut the box down, and have pulled the failed disk and installed a new disk. When the system boots up, /proc/mdstat shows only sda as part of the raid. I then run the various command to rebuild the RAID to /dev/sdb. Everything rebuilds correctly, and upon completion, you look at /proc/mdstat and it shows 2 drives sda1(0) and sdb1(1). Everything looks great. Then you reboot the box ... UGH!!! Once rebooted, sdb is missing again from the RAID. It is like the rebuild never happened. I can walk through the commands to rebuild it again, and it will work, but again, after reboot, the box seems to make sdb just vanish! The real odd thing is, if after reboot, I pull sda out of the box, and try to get the system to load with the rebuilt sdb drive in the system, and when I do, the system actually throws and error just after grub, and says something about drive error, and the system has to shut down. Thoughts??? I'm starting to wonder if grub has something to do with this mess. That the drive isn't being setup within grub to be visible at boot? This RAID array isn't necessary for the system to boot, but when the replacement drive is in there, without SDA it won't boot system, so it makes me believe there is something to that. On top of that, there just seems to be something wonky here the drive falling off of RAID after reboot. I've hit the point of pounding my head on the keyboard. Any help would be greatly appreciated!!!

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• When upgrading from Vista to Windows 7 on a DELL laptop, how do I know which drivers to reinstall an

  - by msorens

  According to Dell's upgrade page for Vista to Windows 7, after using the upgrade assistant the final step is to install drivers. They refer to this page for the order of driver installation, listing 9 items. From there I go to the Dell Drivers and Downloads page, enter my system tag, and get a list of the downloads available for my specific box. That page, by the way, has a link to driver install instructions that lists 10 rather than 9 items. Going to Drivers Help in the side panel and clicking on "In what order should drivers be installed?" shows yet a third list, this one containing 13 items. Not surprisingly, the order of these 3 lists of drivers are not quite the same for the common items! Furthermore, of the 26 files Dell's site recommends for my machine, there are several not shown on any of the 3 lists! I can make determinations for some of these: 6 of them are "applications" so I know which of those I want and that they could probably be safely installed after all drivers. BIOS: I would think this should be unaffected by an OS upgrade so could be skipped. Two tools in the diagnostics category: could probably be done after all drivers. That leaves just a CD/DVD driver and a webcam driver unaccounted for. So my two related questions are these: How critical is the driver installation order and which one do I follow? (Keep in mind this is for an upgrade, not a fresh install.) Where in the order do I insert the CD/DVD and the webcam drivers (if needed) ? Dell's driver download page provides (in theory) the list of all downloads relevant to my specific machine, via the service tag. But do I actually need to reinstall all of them? some? none? How does one determine this? They do label each with Recommended or Optional, so do I need to reinstall all the recommended ones? (Part of the reason for my perplexed frown is that I wonder why I would need to reinstall a CD/DVD driver since I would already be using the drive to install the OS!)

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• What Sort of Server Setup Am I Likely to Need? - School A/V streaming

  - by DeathMagus

  My prior experience with servers has generally been limited to home file-sharing servers, low-traffic web-servers, and the like. This leaves me with the technical knowledge of how to set up a system, but little experience in terms of scaling said system. My current project, however, has me as the technical lead in setting up a school for online audio and video streaming. The difficulty I'm running into is that I don't quite have the experience to guess what they'll need, and they don't have the experience to tell me - so I've tried to ask as many pertinent questions about what they want to do with their server, and here's what I found out: About 1000 simultaneous users, and hoping to expand (possibly significantly) Both video and audio streaming, at obviously the highest quality possible Support for both live and playlist-based streaming. Probably only one channel, but as it's an educational opportunity, I imagine letting them have a few more wouldn't hurt. No word on whether they're locked into Windows or whether Linux is acceptable. Approximate budget - $7000. It may actually be about $2k less than this, because of a mishap with another technology firm (they ordered a $7000 DV tape deck for some reason, and now the company wants them to pay a 30% restocking fee). The tentative decisions I've already made: I'm planning on using Icecast 2 for my streaming server, fed by VLC Shoutcast encoding. Since the school already has a DMZ set up, I plan on placing the Icecast server in there, and feeding it through their intranet from a simple workstation computer in their studios. This system isn't in any way mission critical - it's an education tool (they're a media magnet school), so I figure redundancy is not worthwhile to them from a cost:benefit perspective. What I don't know is this: How powerful of a server will I need? What is likely to be my major throttle - bandwidth? How can I mitigate that? Will I need anything special for the encoding workstation other than professional video and audio capture cards and a copy of VLC? Are there any other considerations that I'm simply missing? Thanks a lot for any help - if there's more information you need, let me know and I'll tell you all I can.

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• Recover strategy single bad sector in moricon

  - by Damon

  This week, my harddisk made me an early christmas present in the form of a single defect sector. To make up for the puny size of the present, it chose a sector inside moricons.dll for that. This means that now the system takes about 5 minutes to boot before Windows gives up and moves on, and there's 2 dozen scary "critical failure" entries in the system log after every boot, which is annoying. OK, admittedly, I shouldn't complain, it could be worse, the bad sector could be in ntldr... SMART info more or less indicates (for what SMART can indicate anyway) that the drive is mostly OK. Soft Read Error Rate has a score of 96, and Current Pending Sector Count has a raw value of 8, which translates to a score of 100. Acronis DriveMonitor makes this an issue (lowering the overall rating to 75%), HDD Health calls it "excellent", giving an overall rating of 95% (which is what this harddisk from day one). No single score is below 95 (power on hours and spin up count), and most are 100 anyway. Well, whatever, I've seen drives with perfect SMART values fail from one second to the other, and drives with moderate values work for years. So, I'm inclined not to put too much weight into that overall. TL;DR Now... to the problem: I don't feel like trashing the disk just yet (that's planned with a new OS install upgrading to Win7 early next year, independently of this issue), but in the mean time, I would still like to have a smoothly running system again. Therefore, I feel tempted to tamper with it, but before I render my system entirely unusable (since I've never done this before), I'd like to verify that my planned procedere is likely to suceed in having a working system again: Copy moricons.dl_ from the Windows install disk, rename it to moricons.zip, and unzip it. This gives an intact 5.1.2600.2180 version (the broken one is 5.1.2600.5512 - but I guess this makes not much of a difference, since it's an icon-only DLL, and an outdated copy should work better than one that can't be read) Run chkdsk /r /f` which will "repair" the file (i.e. delete the file without asking, tell the drive to remap the sector, and toss some unreadable junk into a file with a hexadecimal number) Hopefully Windows still boots after this (is that a reasonable expectation, or do I need to have something like BartPE ready? -- but then again, what's that good for in case chkdsk has nuked the entire file system...) Delete the junk file generated by chkdsk, copy the new DLL to %windir%\system32 Reboot. Pray. Maybe I just shouldn't touch anything, since it still kind of works... if annoying, but it works. Unsure... But, is there anything fundamentally wrong with the planned approach? Is this a sensible approach at all?

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• Why is BIND giving me a SERVFAIL in this case? (Notes inside)

  - by imaginative

  Woke up this morning to a bunch of the following: root@foo:/etc/bind# dig @1.2.3.4 foo.example.com ; <<>> DiG 9.6.1-P2 <<>> @1.2.3.4 foo.example.com ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 36121 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;;foo.example.com. IN A ;; Query time: 0 msec ;; SERVER: 1.2.3.4#53(1.2.3.4) ;; WHEN: Thu Apr 1 09:57:59 2010 ;; MSG SIZE rcvd: 31 Some background on the fictitious "1.2.3.4". It's a slave name server in my nameserver "farm". Technically I have ns1 (being the master) and ns2/ns3. Currently ns1/ns2 are down for maintenance, so I left ns3 at it serving live traffic. That's the point, DNS is supposed to be resilient. Now the odd part is, "1.2.3.4" was serving requests for example.com just fine for the last 4-5 days. This morning I get a phone call that it's non-responsive. After investigation I see the message you see above, SERVFAIL. I looked into the zone file and saw the following: example.com IN SOA ns1.example.com. hostmaster.mail.example.com. ( I wondered if at this point that the nameserver thought it was not authoritative over example.com and adjusted it to the following: example.com IN SOA ns3.example.com. hostmaster.mail.example.com. ( After that, it started responding again for all authoritative queries for example.com. I have no idea why. I thought these things were supposed to be normalized upon zone transfer from ns1 - ns3? Can someone please example why this happened and how to prevent it from happening in the future? I've never had a similar problem, and because I don't understand it well, I might be missing some critical information in this question. So please let me know if I can further add any detail to make things clearer as well. One more thing to note: I have other domains that I'm authoritative for that have their SOA still saying ns1.example.com. and not ns3.example.com. Those domains are serving requests just fine! Is it a matter of time before they stop also and I have to change SOA to ns3.example.com? Is this also only required because ns1 and ns2 are currently offline?

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• Which hardware to VM ratio for Build-Server virtualization?

  - by Martin

  Let's start with saying that I'm a total noob wrt. to server virtualization. That is, I use VMs often during development, but they're simple desktop machine things for me. Now to my problem: We have two (physical) build servers, one master, one slave running Jenkins to do daily tasks and build (Visual C++ Builds) our release packages for our software. As such these machines are critical to our company, because we do lot's releases and without a controlled environment to create them, we can't ship fixes. (And currently there's no proper backup of these machines in place, because they do not hold any data as such - it just would be a major pain to setup them again should they go bust. (But setting up backup that I'd know would work in case of HW failure would even be more pain, so we have skipped that until now.)) Therefore (and for scaling purposes) we would like to go virtual with these machines. Outsourcing to the cloud is not an option, not at all, so we'll have to use on-premises hardware and VM hosts. Each Build-Server (master or slave) is a fully configured (installs, licenses, shares in case of the master, ...) Windows Server box. I would now ideally like to just convert the (two) existing physical nodes to VM images and run them. Later add more VM slave instances as clones of the existing ones. And here begin my questions: Should I go for one VM per one hardware-box or should I go for something where a single hardware runs multiple VMs? That would mean a single point of failure hardware wise and doesn't seem like a good idea ... or?? Since we're doing C++ compilation with Visual Studio, I assume that during a build the hardware (processor cores + disk) will be fully utilized, so going with more than one build-node per hardware doesn't seem to make much sense?? Wrt. to hardware options, does it make any difference which VM software we use (VMWare, MS, Virtualbox, ... ?) (We're using Windows exclusively for our builds.) Regarding budget: We have a normal small company (20 developers) budget for this. ;-) That is, if it's going to cost a few k$ it's going to cost. If it's free - the better. I strongly prefer solutions where there's no multi-k$ maintenance costs per year.

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• Detection of battery status totally messed up

  - by Faabiioo

  I already posted this question in the Ubuntu forum and stackOverflow. I forward it here with the hope to find some different opinions about the problem. I have an Acer TravelMate 5730, which is 3 y.o., running Ubuntu 10.04 LTS. One year ago I changed the battery because the old one died. Since then, everything worked like a charm. A week ago I was using my laptop running on battery; it was charged up to 60%. Suddenly it shut down and for about 24h it was like the battery was totally broken: it didn't charge anymore and the 'upower --dump' said state: critical. I was kind of resigned to buy a new battery, when suddenly the orange light became green: battery was charged and actually working; strangely the battery indicator was stuck to 100%, even after 2 hours running. I tried again with 'upower --dump' or 'acpi -b' commands and it kept saying battery is discharging, though maintaining the percentage to 100%. Thus, battery working fine up to 3 hours, without any warning when it was almost empty, likely to result in a brute shut down. Today something different. the 'upower --dump' command says: ... present: yes rechargeable: yes state: fully-charged energy: 0 Wh energy-empty: 0 Wh energy-full: 65.12 Wh energy-full-design: 65.12 Wh energy-rate: 0 W voltage: 14.481 V percentage: 0% capacity: 100% technology: lithium-ion I tried to boot WinXP and the problem is pretty much the same, with the battery fully-charged, percentage equal to 0% and no way to fix it. While writing, the situation has changed again: present: yes rechargeable: yes state: charging energy: 0 Wh energy-empty: 0 Wh energy-full: 65.12 Wh energy-full-design: 65.12 Wh energy-rate: 0 W voltage: 14.474 V percentage: 0% capacity: 100% technology: lithium-ion ...charging, but it does not charge up. (Recall, the battery lasted 3 hours until yesterday!). So, the big question is: is it an hardware issue, like a dedicated internal circuit is broken? or maybe it is just the battery that must be changed. Or, rather, some BIOS problem that could be fixed in some way. I'd appreciate every help that can shed some light on this annoying problem thanks

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• Nginx https rewrite turns POST to GET

  - by x7311

  My proxy server runs on ip A and this is how people access my web service. The nginx configuration will redirect to a virtual machine on ip B. For the proxy server on IP A, I have this in my sites-available server { listen 443; ssl on; ssl_certificate nginx.pem; ssl_certificate_key nginx.key; client_max_body_size 200M; server_name localhost 127.0.0.1; server_name_in_redirect off; location / { proxy_pass http://10.10.0.59:80; proxy_redirect http://10.10.0.59:80/ /; proxy_set_header Host $http_host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; } } server { listen 80; rewrite ^(.*) https://$http_host$1 permanent; server_name localhost 127.0.0.1; server_name_in_redirect off; location / { proxy_pass http://10.10.0.59:80; proxy_redirect http://10.10.0.59:80/ /; proxy_set_header Host $http_host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; } } The proxy_redirect was taken from how do I get nginx to forward HTTP POST requests via rewrite? Everything that hits the public IP will hit 443 because of the rewrite. Internally, we are forwarding to 80 on the virtual machine. But when I run a python script such as the one below to test our configuration import requests data = {'username': '....', 'password': '.....'} url = 'http://IP_A/api/service/signup' res = requests.post(url, data=data, verify=False) print res print res.json print res.status_code print res.headers I am getting a 405 Method Not Allowed. In nginx we found that when it hit the internal server, the internal nginx was getting a GET request, even though in the original header we did a POST (this was shown in the Python script). So it seems like rewrite has problem. Any idea how to fix this? When I commented out the rewrite, it hits 80 for sure, and it went through. Since rewrite was able to talk to our internal server, so rewrite itself has no issue. It's just the rewrite dropped POST to GET. Thank you! (This will also be asked on Nginx forum because this is a critical blocker...)

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