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  • Software Raid 10 corrupted superblock after dual disk failure, how do I recover it?

    - by Shoshomiga
    I have a software raid 10 with 6 x 2tb hard drives (raid 1 for /boot), ubuntu 10.04 is the os. I had a raid controller failure that put 2 drives out of sync, crashed the system and initially the os didnt boot up and went into initramfs instead, saying that drives were busy but I eventually managed to bring the raid up by stopping and assembling the drives. The os booted up and said that there were filesystem errors, I chose to ignore because it would remount the fs in read-only mode if there was a problem. Everything seemed to be working fine and the 2 drives started to rebuild, I was sure that it was a sata controller failure because I had dma errors in my log files. The os crashed soon after that with ext errors. Now its not bringing up the raid, it says that there is no superblock on /dev/sda2, even if I assemble manually with all the device names. I also did a memtest and changed the motherboard in addition to everything else. EDIT: This is my partition layout Disk /dev/sdb: 2000.4 GB, 2000398934016 bytes 255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x0009c34a Device Boot Start End Blocks Id System /dev/sdb1 * 2048 511999 254976 83 Linux /dev/sdb2 512000 3904980991 1952234496 83 Linux /dev/sdb3 3904980992 3907028991 1024000 82 Linux swap / Solaris All 6 disks have the same layout, partition #1 is for raid 1 /boot, partition #2 is for raid 10 far plan, partition #3 is swap, but sda did not have swap enabled EDIT2: This is the output of mdadm --detail /dev/md1 Layout : near=1, far=2 Chunk Size : 64k UUID : a0feff55:2018f8ff:e368bf24:bd0fce41 Events : 0.3112126 Number Major Minor RaidDevice State 0 8 34 0 spare rebuilding /dev/sdc2 1 0 0 1 removed 2 8 18 2 active sync /dev/sdb2 3 8 50 3 active sync /dev/sdd2 4 0 0 4 removed 5 8 82 5 active sync /dev/sdf2 6 8 66 - spare /dev/sde2 EDIT3: I ran ddrescue and it has copied everything from sda except a single 4096 byte sector that I suspect is the raid superblock EDIT4: Here is some more info too long to fit here lshw: http://pastebin.com/2eKrh7nF mdadm --detail /dev/sd[abcdef]1 (raid1): http://pastebin.com/cgMQWerS mdadm --detail /dev/sd[abcdef]2 (raid10): http://pastebin.com/V5dtcGPF dumpe2fs of /dev/sda2 (from the ddrescue cloned drive): http://pastebin.com/sp0GYcJG I tried to recreate md1 based on this info with the command mdadm --create /dev/md1 -v --assume-clean --level=10 --raid-devices=6 --chunk=64K --layout=f2 /dev/sda2 missing /dev/sdc2 /dev/sdd2 missing /dev/sdf2 But I can't mount it, I also tried to recreate it based on my initial mdadm --detail /dev/md1 but it still doesn't mount It also warns me that /dev/sda2 is an ext2fs file system but I guess its because of ddrescue

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  • Can I use one virtualbox disk for multiple machines?

    - by mxp
    I'm not sure what search term to use and skimming through the VirtualBox manual didn't help me either, so I ask my two questions here... My setup is this: PC with dual boot into Windows 7 and a Debian operating system (both 64bit). I've created a virtual machine (Kubuntu, 64bit) under Windows and put it's VDI file on a SMB share of my NAS. Then I created a VM under linux using the same settings for memory etc and assigned the existing VDI file to it. My idea was that I could use that virtual machine from Windows and Linux as well. (1) Is this generally something that should work without problems? I noticed that snapshots get me into trouble because they appear to be not visible from the other operating system: The snapshots I took after installing the guest system are not visible under Linux. That's why I shut down the VM after usage and not save its state while it's running. My current problem is this: I have used the VM under Windows first, then under Linux. Now it will only start on Linux. When trying this on Windows the guest OS detects some kind of hard disk error and fails to boot because it cannot mount its drive. Obviously the virtual hard disk won't fail so it must have something to do with me using it under Linux. (2) How can I fix that? Update: It also looks like any changes I made in the VM under Linux have been reset by trying to boot it under Windows. Looks like it's back to the latest snapshot. I'm confused... Update The answer to my first question can be found below. In short: It works, as long as you don't use snapshots. The answer to my second question is this: Under Windows set the VM back to the latest snapshot and then discard the snapshot so it gets merged. There should be no snapshots left at the end. If you have multiple snapshots, discard the earliest ones first (Snapshot 1, then 2, 3, ...). I'm not sure what happens if you start at the end (.., 3, 2, 1). This of course leads to some data loss since you revert all changes since the last snapshot. But at least the VM is usable again.

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  • trouble when shutdown or restart in windows xp getting a black screen asking to try and start windows normally or safe mode than it runs a chk disk

    - by Brenda D Thomas
    I recently reinstalled windows xp on my dell latitude d410 laptop, everything works fine as long as I don't shut down, when I do, I get a black screen with a list of choices, it gives me the option of trying to start windows normally or different safe modes, than a blue screen comes up and runs a check disk, it even ask me to pick a restore point the last time, which I did, I'm afraid to turn the computer off or restart it, what could be wrong?

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  • TrueCrypt partition will no longer mount

    - by sparkyuiop
    I am hoping for some advice to help me out of my situation, with luck. I have a computer running Windows 7 Ultimate x64 with 3 hard disks installed. On my 2TB hard disk 2 (non-system disk) I have 4 partitions. One is for music, another for video, a downloads partition and a 500GB RAW Truecrypt encrypted partition / volume that I had setup to mount with 4 photographs used as keyfiles. The 4 photographs are located in my 'Documents' partition which is one of four partitions on my 1.5TB hard disk 1 (non-system disk) When I setup the disk encryption I did not (I'm 99% sure) create a password, I only used the 4 photograph keyfiles to mount the volume. Recently my 1TB hard disk 0 (system / boot) started to fail so I decided to replace it. I was going to clone the old disk to a new disk but decided that a fresh installation would be more beneficial. Once I had transferred all the required 'User Data' from my old hard disk 0 (C: disk) I discarded it. I reinstalled Truecrypt, pointed to the partition, selected my 4 keyfiles photographs and I mounted my encrypted volume with no issues. In fact I mounted it several times after re-installing Windows and after reboots. Now all of a sudden when I try and mount it I get the message "incorrect keyfile(s) and/or password or not a Truecrypt volume". Now I am not sure why this happened as I do not recall exactly what I did between last mounting the volume successfully and it not mounting. Here are some of the possible things I may have done to cause it to stop working but I am at a loss as to where to start to try and resolve the problem. 1. I had swapped the drive letters to a preferred order. 2. I possibly swapped the physical SATA connectors on the mainboard. 3. I enabled 'Hot Plugging' for the two non-system hard disk SATA ports and the DVD SATA port in the BIOS. I have tried changing the encrypted partition drive letter as suggested in another post but this does not help. On my old system the encrypted drive was drive "X". I have about tried it with all the other free drive letters but alas nothing changes. I do not recall what drive letter was allocated to the encrypted partition before I changed them all. I have not tried to change the letter back to what it possibly was to start with as I am happy with the current layout. I will try this is anyone thinks it would be worthwhile though. I do hope I have managed to convey my situation in an understandable manner and live in hope someone could help me recover years of personal files. Thank you very much for taking the time to read my post and for any suggestions you may offer. Regards Phillip Thorne (UK) Anyone???

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  • VM Virtual guest machine disk defrag improves performance, myth or reality?

    - by jafin
    In operation of a virtual Vmware or Hyper-V guest typically advice is given to defrag the host and virtual disk images so to result in improved performance. Something like a cmd: vmware-vdiskmanager -d <file.vmdk> works great. Yet I can't find any qualitive evidence that suggest defraging inside the guest VM improves performance. Does anyone have advice or evidence that doesn't come from a commercial defragger's whitepaper that suggests inside guest defragging helps?

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  • Zend_Cache save from command line and access from browser

    - by Krishna Sunuwar
    May be I am this is super-easy but I couldnt' figure out way. I have script running in command line which save cache using Zend_Cache $frontendOptions = array( 'lifetime' => NULL, 'automatic_serialization' => true ); $backendOptions = array( 'cache_dir' => "/home/tmp/cache" ); $cache = Zend_Cache::factory('Core', 'File', $frontendOptions, $backendOptions); $vars = Array("id1" => "12121", "id2" => "2232"); $cache->save($vars, "p_11"); I can access saved cache from command line: $cache->load("p_11"); In above both case, I have app.php file that run in command line using php-cli. Now, I want to access p_11 cache using browser something like http://mytestserve.lan/test_cache.php I have create object with cache factory like above. All the parameters are same as above. However when I try to load cache p_11, i do not variables set from command line. What went wrong?

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  • Why is Core Data not persisting these changes to disk?

    - by scott
    I added a new entity to my model and it loads fine but no changes made in memory get persisted to disk. My values set on the car object work fine in memory but aren't getting persisted to disk on hitting the home button (in simulator). I am using almost exactly the same code on another entity in my application and its values persist to disk fine (core data - sqlite3); Does anyone have a clue what I'm overlooking here? Car is the managed object, cars in an NSMutableArray of car objects and Car is the entity and Visible is the attribute on the entity which I am trying to set. Thanks for you assistance. Scott - (void)viewDidLoad { myAppDelegate* appDelegate = (myAppDelegate*)[[UIApplication sharedApplication] delegate]; NSManagedObjectContext* managedObjectContex = appDelegate.managedObjectContext; NSFetchRequest* request = [[NSFetchRequest alloc] init]; NSEntityDescription* entity = [NSEntityDescription entityForName:@"Car" inManagedObjectContext:managedObjectContex]; [request setEntity:entity]; NSSortDescriptor* sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"Name" ascending:YES]; NSArray* sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [request setSortDescriptors:sortDescriptors]; [sortDescriptors release]; [sortDescriptor release]; NSError* error = nil; cars = [[managedObjectContex executeFetchRequest:request error:&error] mutableCopy]; if (cars == nil) { NSLog(@"Can't load the Cars data! Error: %@, %@", error, [error userInfo]); } [request release]; } - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath*)indexPath { Car* car = [cars objectAtIndex:indexPath.row]; if (car.Visible == [NSNumber numberWithBool:YES]) { car.Visible = [NSNumber numberWithBool:NO]; [tableView cellForRowAtIndexPath:indexPath].accessoryType = UITableViewCellAccessoryNone; } else { car.Visible = [NSNumber numberWithBool:YES]; [tableView cellForRowAtIndexPath:indexPath].accessoryType = UITableViewCellAccessoryCheckmark; } }

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  • how i can retrive files from folder on hard-disk and how to display uplaoded file data into a textar

    - by Deepak Narwal
    I have made a application form in which i am asking for username,password,email id and user's resume.Now after uploading resume i am storing it into hard disk into htdocs/uploadedfiles/..in a format something like this username_filename.In database i am storing file name,file size,file type.Some coading for this i am showing here $filesize=$_FILES['file']['size']; $filename=$_FILES['file']['name']; $filetype=$_FILES['file']['type']; $temp_name=$_FILES['file']['tmp_name']; //temporary name of uploaded file $pwd_hash = hash('sha1',$_POST['password']); $target_path = "uploadedfiles/"; $target_path = $target_path.$_POST['username']."_".basename( $_FILES['file']['name']); move_uploaded_file($_FILES['file']['tmp_name'], $target_path) ; $sql="insert into employee values ('NULL','{$_POST[username]}','{$pwd_hash}','{$filename}','{$filetype}','$filesize',NOW())"; Now i have two questions 1.NOw how i can display this file data into a textarea(something like naukri.com resume section) 2.How one can retrive that resume file from folder on hard-disk.What query should i write to fetch this file from that folder.I know how to retrive data from database but i dont know how to retrive data from a folder in hard-disk like in the case if user want to delete this file or he wnat to download this file.How i can do this

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  • How to R/W hard disk when CPU is in Protect Mode?

    - by smwikipedia
    I am doing some OS experiment. Until now, all my code utilized the real mode BIOS interrupt to manipulate hard disk and floppy. But once my code enabled the Protect Mode of the CPU, all the real mode BIOS interrupt service routine won't be available. How could I R/W the hard disk and floppy? I have a feeling that I need to do some hardware drivers now. Am I right? Is this why an OS is so difficult to develop? I know that hardwares are all controlled by reading from and writing to certain control or data registers. For example, I know that the Command Block Registers of hard disk range from 0x1F0 to 0x1F7. But I am wondering whether the register addresses of so many different hardwares are the same on the PC platform? Or do I have to detect that before using them? How to detect them?? For any responses I present my deep appreciation.

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  • SQL SERVER – Database Dynamic Caching by Automatic SQL Server Performance Acceleration

    - by pinaldave
    My second look at SafePeak’s new version (2.1) revealed to me few additional interesting features. For those of you who hadn’t read my previous reviews SafePeak and not familiar with it, here is a quick brief: SafePeak is in business of accelerating performance of SQL Server applications, as well as their scalability, without making code changes to the applications or to the databases. SafePeak performs database dynamic caching, by caching in memory result sets of queries and stored procedures while keeping all those cache correct and up to date. Cached queries are retrieved from the SafePeak RAM in microsecond speed and not send to the SQL Server. The application gets much faster results (100-500 micro seconds), the load on the SQL Server is reduced (less CPU and IO) and the application or the infrastructure gets better scalability. SafePeak solution is hosted either within your cloud servers, hosted servers or your enterprise servers, as part of the application architecture. Connection of the application is done via change of connection strings or adding reroute line in the c:\windows\system32\drivers\etc\hosts file on all application servers. For those who would like to learn more on SafePeak architecture and how it works, I suggest to read this vendor’s webpage: SafePeak Architecture. More interesting new features in SafePeak 2.1 In my previous review of SafePeak new I covered the first 4 things I noticed in the new SafePeak (check out my article “SQLAuthority News – SafePeak Releases a Major Update: SafePeak version 2.1 for SQL Server Performance Acceleration”): Cache setup and fine-tuning – a critical part for getting good caching results Database templates Choosing which database to cache Monitoring and analysis options by SafePeak Since then I had a chance to play with SafePeak some more and here is what I found. 5. Analysis of SQL Performance (present and history): In SafePeak v.2.1 the tools for understanding of performance became more comprehensive. Every 15 minutes SafePeak creates and updates various performance statistics. Each query (or a procedure execute) that arrives to SafePeak gets a SQL pattern, and after it is used again there are statistics for such pattern. An important part of this product is that it understands the dependencies of every pattern (list of tables, views, user defined functions and procs). From this understanding SafePeak creates important analysis information on performance of every object: response time from the database, response time from SafePeak cache, average response time, percent of traffic and break down of behavior. One of the interesting things this behavior column shows is how often the object is actually pdated. The break down analysis allows knowing the above information for: queries and procedures, tables, views, databases and even instances level. The data is show now on all arriving queries, both read queries (that can be cached), but also any types of updates like DMLs, DDLs, DCLs, and even session settings queries. The stats are being updated every 15 minutes and SafePeak dashboard allows going back in time and investigating what happened within any time frame. 6. Logon trigger, for making sure nothing corrupts SafePeak cache data If you have an application with many parts, many servers many possible locations that can actually update the database, or the SQL Server is accessible to many DBAs or software engineers, each can access some database directly and do some changes without going thru SafePeak – this can create a potential corruption of the data stored in SafePeak cache. To make sure SafePeak cache is correct it needs to get all updates to arrive to SafePeak, and if a DBA will access the database directly and do some changes, for example, then SafePeak will simply not know about it and will not clean SafePeak cache. In the new version, SafePeak brought a new feature called “Logon Trigger” to solve the above challenge. By special click of a button SafePeak can deploy a special server logon trigger (with a CLR object) on your SQL Server that actually monitors all connections and informs SafePeak on any connection that is coming not from SafePeak. In SafePeak dashboard there is an interface that allows to control which logins can be ignored based on login names and IPs, while the rest will invoke cache cleanup of SafePeak and actually locks SafePeak cache until this connection will not be closed. Important to note, that this does not interrupt any logins, only informs SafePeak on such connection. On the Dashboard screen in SafePeak you will be able to see those connections and then decide what to do with them. Configuration of this feature in SafePeak dashboard can be done here: Settings -> SQL instances management -> click on instance -> Logon Trigger tab. Other features: 7. User management ability to grant permissions to someone without changing its configuration and only use SafePeak as performance analysis tool. 8. Better reports for analysis of performance using 15 minute resolution charts. 9. Caching of client cursors 10. Support for IPv6 Summary SafePeak is a great SQL Server performance acceleration solution for users who want immediate results for sites with performance, scalability and peak spikes challenges. Especially if your apps are packaged or 3rd party, since no code changes are done. SafePeak can significantly increase response times, by reducing network roundtrip to the database, decreasing CPU resource usage, eliminating I/O and storage access. SafePeak team provides a free fully functional trial www.safepeak.com/download and actually provides a one-on-one assistance during such trial. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: About Me, Pinal Dave, PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL Utility, T SQL, Technology

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  • Hash Sum Mismatch using preseed (Ubuntu Server 12.04)

    - by xorma
    My install through Preseed fails at around 80% on Select and Install Software. In VT-4, I can see Hash Sum mismatch errors. This may be because I am going through a firewall which is caching files. There is no-cache option for apt but I can't seem to get it to work with Preseed. Have tried: d-i debian-installer/no-cache string true d-i apt-setup/no-cache boolean true d-i preseed/early_command string mkdir -p /target/etc/apt/apt.conf.d; echo "Acquire::http {No-Cache=True;};" > /target/etc/apt/apt.conf.d/no-cache but none of these are working. It appears that the early_command occurs too early so is over written once install starts. I'm not sure if the other commands are even correct. Anyone know what is the correct way of disabling achieving this through Preseed?

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  • Local Data Cache - How do I refresh the local db when I add fields to remote db?

    - by Chu
    I'm using a Local Data Cache in an ASP.NET 3.5 environment. I made a change in my main database by adding a new field. I double click on my .SYNC file in my project to startup the Local Data Cache wizard again. The wizard starts and I click OK with the hopes that it'll re-query my database and add the new field to the local database file. Instead, I get an error saying "Synchronizing the databae failed with the message: Unable to enumerate changes at the DbServerSyncProvider..." The only way I know to get things working again is to delete the .SYNC file along with the local database and start it from scratch. There's got to be an easier way... anyone know it?

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  • Better performance to Query the DB or Cache small result sets?

    - by user169867
    Say I need to populate 4 or 5 dropdowns w/ items from a database. Each drop down will have < 15 items in it. These items almost never change. Now I could query the DB each time the page is accessed or I could grab the values from a custom class that would check to see if they already exist in ASP.Net's cache and only if they don't query the DB to update the cache. It's trivial for me to write but I'm unsure if the performace would be better or not. I think it would be (although not likely anything huge). What do you think?

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  • Observer not clearing cache in Rails 2.3.2 - please help.

    - by Jason
    Hi, We are using Rails 2.3.2, Ruby 1.8 & memcache. In my Posts controller I have: cache_sweeper Company::Caching::Sweepers::PostSweeper, :only => [:save_post] I have created the following module: module Company module Caching module Sweepers class PostSweeper < ActionController::Caching::Sweeper observe Post def after_save(post) Rails.cache.delete("post_" + post.permalink) end end end end end but when the save_post method is invoked, the cache is never deleted. Just hoping someone can see what I am doing wrong here. Thanks.

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  • Coherence Query Performance in Large Clusters

    - by jpurdy
    Large clusters (measured in terms of the number of storage-enabled members participating in the largest cache services) may introduce challenges when issuing queries. There is no particular cluster size threshold for this, rather a gradually increasing tendency for issues to arise. The most obvious challenges are that a client's perceived query latency will be determined by the slowest responder (more likely to be a factor in larger clusters) as well as the fact that adding additional cache servers will not increase query throughput if the query processing is not compute-bound (which would generally be the case for most indexed queries). If the data set can take advantage of the partition affinity features of Coherence, then the application can use a PartitionedFilter to target a query to a single server (using partition affinity to ensure that all data is in a single partition). If this can not be done, then avoiding an excessive number of cache server JVMs will help, as will ensuring that each cache server has sufficient CPU resources available and is also properly configured to minimize GC pauses (the most common cause of a slow-responding cache server).

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  • How Do I Rollout WP-Cache To 1000 WordPress Blogs?

    - by Volomike
    My client has 1000 WordPress blogs hosted on a server for customers. Each one is in its own domain through cpanel and SuPHP, running in CGI mode on Apache2.2. Now he wants me (I'm the PHP programmer) to get WP-Cache loaded out on each of these blogs and not just activated, but enabled. He also wants the timeout value set to 2 days instead of the default setting. I have root on LAMP. What is the preferred way to roll out an update to each blog such that on a page view, it sees if WP-Cache is enabled or not. If not, it needs to copy it out from a central source, activate it, and then enable it along with the different timeout value being used.

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