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Disk Initialization

By Michelle2
Jul 14, 2006
  1. One of the hard drives on my raid 5 server has failed. The engineer replaced but now we cant see the shares that was on the original drive.

    Anyone know what disk initialization will do? Will it wipe the data underneath the container?

    Panic
     
  2. pcaceit

    pcaceit TS Rookie Posts: 315

    Cant remember which protection method RAID5 is but, i believe initialization is neccessary to make that new disk part of the recovery method, like if it were part of a Stripe set,volume set etc... so i would say you have to initialize your new Disk make your RAID setup work. (google it)

    View more about it in link below
    http://www.gamepc.com/labs/view_content.asp?id=r52005&page=3&cookie_test=1
     
  3. Michelle2

    Michelle2 TS Rookie Topic Starter Posts: 35

    Thanks.

    Done and data lost.

    Dell engineer fitted a 73gb drive instead of a 150gb drive. Had a second replacement of 300gbs, but all done too late.

    Now in search of a good raid array recovery software.
     
  4. pcaceit

    pcaceit TS Rookie Posts: 315

    Hi again Michelle2
    Was not good to see that....,Think Dell engineer should have Known better.

    Still I dont believe that all is Lost, the wole idea of raid is meant to prevent that, I have done a recovery recently on a repartitioned and reformatted Drive and used Active Undelete in link below, it worked perfectly.
    http://www.active-undelete.com/

    There's also this one here on Techspot Downloads which lists Raid recovery as one of its supported features.
    http://www.techspot.com/downloads/382-active-file-recovery-for-windows.html

    There's this link as well which shows in good detail how to setup Raid5 and other versions of raid as well.
    http://docs.sun.com/app/docs/doc/802-2042/6i61juum3?a=view

    Can you say which Raid config utility you are using and give me an update?

    Thanks and Good luck

    Regards, pcaceit
     
  5. Rick

    Rick TechSpot Staff Posts: 4,573   +65

    For the future, initialization always results in data loss.

    RAID 5 is three or more disks. The disks are striped, meaning your data is split across every disk. Each disk also contains a portion of your parity data (used for recovery). Total Capacity = Disk1 + Disk2 - Disk3 (Assuming all disks are the same size)

    RAID 5 is capable of sustaining only ONE drive failure, regardless of the number of drives in the array.

    If a disk fails in your RAID 5 array, it should be removed and replaced, so that was right. You'll add the disk (Same size or larger as the others) into your RAID 5 array / container using your RAID utility (Do not initialize). Then you should be able to rebuild your array. It may take some time, but your array should be fine once you complete the rebuild.

    You can delete and recreate raid arrays / containers usually without data loss. Just make sure you don't initialize, format or otherwise delete anything in addition to JUST the raid array. All RAID setup utilities (That I've seen) should warn you before data is deleted, so take the warnings seriously. :) Data is not to be toyed with...
     
  6. pcaceit

    pcaceit TS Rookie Posts: 315

    Hi Rick, Thanks for that explaination.

    can you answer a bit more on this for me if you got time please?

    So what is the Command/Syntax/Process called for executing the recovery process when you replace a failed member? and if recovery tools can recover the data on the other Disks in the set, will michelle2 be able to get back the data when the failed member is replaced? and is the initialize process the process that initialiy implements the RAID operation?
    and could you just create volumes of equal size on each Disk to make up the array and have the unused space available for other purposes?

    (my appologies to you michelle2, i hoped you would have googled it for more info as i suggested as well)
     
  7. Rick

    Rick TechSpot Staff Posts: 4,573   +65

    If the drive is hot-swappable, usually nothing has to be done. You remove the failing drive and insert the replacement drive. The controller will automatically add the drive to the array. Using the parity information stored on the other two or more working drives, the controller will rebuild the data accordingly. This process takes at least a few hours usually. For non HSCs, it may be necessary to enter the controller setup utility, but this utility is usually menu driven.

    I'm unfamiliar with software-based RAID 5 (Under Linux) for example, so I'm unsure what commands you'd use. But you could probably get more details by brining up the man page for the RAID utility: man raid

    Windows Server has software RAID 5 as well. You can rebuild an array using Disk Manager through the GUI (Start / Run / diskmgmt.msc )

    RAID 5 is designed to still work while one drive has failed. One failed RAID member should be more of a nuissance in RAID 5 than an actual emergency and since this is the case, (thankfully) Michelle's data should be completely accessible at the software level. There is the potential to recover all of Michelle's data with only two drives, although the third one should definitely be replaced.

    'Initialize' can mean two things... A quick partition removal or a more thorough, unconditional format. In both cases, it prepares the RAID array for use. If Michelle performed a quick initialization, regular partition recovery utilities should be able to get her data back... And quite completely. My personal favorite is Active@Partition Recovery, because I've used it many times and it has worked so many times for me. I've never used this program on a RAID array though, so I don't know if there will be complications. It's a free download (to try, at least!)... So you can find out if will work or not before you commit to purchasing it (it's inexpensive). There may also be newer, better tools out there... Not sure.

    If the array has been initialized unconditionally (would have taken a long, long time to initialize), then Michelle has gotten herself into quite a pickle. Her data will be substantially more difficult to recover... There IS software out there that can get some of the data back, but I've been largely unsuccessful attempting such recovery. It would seem attempting recovery at the software level (after an unconditional format) is only useful when you just have a few documents or pictures you want back. If you want your whole directory structure back with large files etc... I would deem it unlikely. These data forensic programs are very expensive as well, such as Ontrack's data recovery suite which apparently now runs at $1500 or so. :\ I remember when it used to be only $900.... :)

    Not that I'm aware of, but I know what you're thinking of. The controller will use the smallest drive as the size of the volumes, so larger disks will have unused storage capacity. You would think the left over space would be partitionable, but I don't think it is (However, I don't know this for sure).

    BUT, even if it is partitionable, I believe this would be a very improper setup anyhow, as RAID 5 is usually hot-swappable and if you have miscellaneous partitions on a couple of the disks, things could get very messy during an emergency. :)
     
  8. Michelle2

    Michelle2 TS Rookie Topic Starter Posts: 35

    Guys thank you for your help

    The problem I had was the Dell Engineer came in, he swapped a 146gb HDD with a 73GB HDD, brought the HDD up in the Raid controller, windows wouldnt see the drive and asked for initialization.

    For me initialization = data loss.

    Dell Open manage software has the ability to add the HDD to the raid array container, which he started, but as we couldnt see the data and was asking for initialization he had the "bright" idea that he could put the old drive back in, which he did and still no data...

    Dell sent out a 300gb HDD to replace the original 146GB drive, and I added to the container, via Dell open manage, still unable to see the data had to go through the initialization and have spent the weekend restoring the data and exchange.

    For future ref: does you know of any good data recovery tools that we can use onsite rather than sending system away?

    Thank you
     
  9. Michelle2

    Michelle2 TS Rookie Topic Starter Posts: 35

    Hi Rick and pcaceit,

    Would there be any chance either of you could advise as to what could have happened to the data when the smaller drive was fitted?

    We are going to be calling some comp and I need to put in words a possible scenario!

    Thank you for all the info

    Michelle
     
  10. Rick

    Rick TechSpot Staff Posts: 4,573   +65

    If a smaller drive was placed into the array and it was initialized, then your partitions were destroyed and probably recreated as smaller partitions. I don't know enough about what goes on under the hood to give more details though.

    Partition damage is generally recoverable to some extent. But if the drives have been written to since (like a new install of Windows etc..), data will become exponentially harder to restore.
     
  11. Michelle2

    Michelle2 TS Rookie Topic Starter Posts: 35

    Thanks Rick, I really appreciate your help.

    What I think may have happened, is the Dell engineer, put the drive in, run the PERC array BIOS, which via a load of error messages would have tried to reconfigure the other drives to 73gb aswell. Although no Initialization took place we still lost all of the data.

    At least the SAM was on the C: not D!

    Cheers
     
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