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Splitting a JBOD

Discussion in 'Hardware' started by Koroshiya, Oct 2, 2008.

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  1. Koroshiya

    Koroshiya Thread Starter

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    Ok, before I get slammed with questions like, "Why'd you even use JBOD in the first place." This was a crappy 1TB external. The company used a hardware JBOD to raid two 500GB HDD's together. Not my choice.

    The issue I'm having is that this particular drive has a known problem with the JBOD just straight breaking. This is the second time this has happened to me and I want to try and salvage my data.

    I've been reading about JBOD and RAID but I've decided that it might not be worth my time and effort. So, I broke open the enclosure (warranty already expired) and placed the drives into my computer. Now, before I turn it on, I want to know a couple things:

    1) Have I compromised retrieving my data?
    2) Now the the drives are separated, will they run as separate drives? Or was the data striped, thus forcing me to possibly re-JBOD / RAID?
    3) Is there any way I can avoid having to format my data?

    Thanks, in advance!
     
  2. fairnooks

    fairnooks Banned

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    Someone will correct me if I'm wrong but JBOD is just a form of spanning where the disks are dynamic I think. Seems like recovery software would be able to look at the data and see most of the data there, but in Windows I'm pretty sure they won't function properly when seperated because Windows is expecting to see both drives as one large partition.

    So I think true JBOD is not striped so data recovery should be possible on an individual basis but the only way to make them work in windows again is to convert them back to basic drives again which deletes the data stored there as far as Windows is concerned.
     
  3. Koroshiya

    Koroshiya Thread Starter

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    To be sure I'm on the right page, the best way for me to recover my data is to use a recovery software on each drive, back up the data onto a disc and then format them?

    :Edit:
    Forgive me if I'm overly paranoid about this. Some of this data is irreplaceable; stories I've written , fraps videos and spreadsheets out the wazoo.
     
  4. fairnooks

    fairnooks Banned

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    If you want to go strickly by protocol, you would make an exact image copy of the disk(s) and then work on recovering the data from the copy(s). As long as you don't write anything to the drive(s) you should be ok but there's always the risk that things could happen to make the situation worse with the only copy you have.

    Its possible that one of the drives failed and that caused the array failure but hopefully both will show up in the BIOS. If the disks were simple spanned JBOD, recovery software like GetDataBack (http://www.runtime.org/) should be able to see it well and you would indeed read that data off those drives to another location.

    Good luck. Let us know about more snags if any arise. If recovery software doesn't see anything post with the make and model of the external that was, so maybe someone knows or can find out more about how exactly the two drives were bridged.
     
  5. Koroshiya

    Koroshiya Thread Starter

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    You're fantastic, man. I really appreciate it. I'll get on that, right away!
     
  6. crjdriver

    crjdriver Moderator

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    Actually jbod is a type of raid AND I doubt that you will be able to access the drives unless you connect them to the same type of raid controller. ie the same type used by the external case. I have a link somewhere that has software to recover raid type drives without a controller or the same controller. I need to find that to post it for you.
     
  7. crjdriver

    crjdriver Moderator

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    BTW this is WHY we stress backup soooo much here. If you do not have at least two copies of data on separate media ie hd, dvdrs, etc; it means you do not care about the data. All drives fail. It is only a question of when your drive will fail.
     
  8. crjdriver

    crjdriver Moderator

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  9. fairnooks

    fairnooks Banned

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    Seeing if you can carefully read the drives individually is a good starting point and may be all the further it needs to be taken if successful. Technically it might be pretty black and white as to what bridging technique is supposed to be employed in what situation according to what it is called but in real life, it doesn't happen that way.

    For instance I have a CADB-U32 Cavalry 1TB external drive (two 500s) that uses spanning when in the "one drive" mode and they actually call it JBOD when they are functioning as seperate drives, which technically still falls under JBOD but what I think of as just two drives in a box, like two drives on one controller, not JBOD which implies the efficient use of different sized disks in an environment that wouldn't be efficient at all (or not even possible) in Raid 0 or 1 and not optimum in a Raid 5 if the discrepency was very large.

    Of course just because it makes sense to do it a certain way doesn't mean it will be done that way since other economic forces are at work and Raid 0s still get employed on USB externals even though the maximum bus speed negates any advantage of such a configuration.
     
  10. MattsComp

    MattsComp

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    Fairnooks - great post. I'm actually trying to recover a faulty drive - exactly the same as you have (Cav 1TB in one drive mode) and was trying to clarify your point - you're saying do take it apart and see if you can load each drive? I was either gonna try it again in Windows XP, failing that, ddrescue in linux...
     
  11. fairnooks

    fairnooks Banned

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    You might do that first just to check and see if one of the drives has died and if so, which one, because that might stop you right there. I actually took mine apart and jumpered it so each drive is seperately identified. I'm not sure if RAID 0 is otherwise in use or just simple volume spanning. I had an Omega 1TB dual drive die and it was the "master" volume so I don't know if the good drive was 0 or spanned since I couldn't analyze the master simple volume and the company is not forthcoming on the particulars of what they're using. I think it was spanned becuase just before it totally died it read 930 GB size for the one 465 GB drive and the other one read 465.

    If its raid 0 and one dirve died, game over. There are more options with spanned dynamic disk configuration including a possible hack to convert back to basic without loss of data.(http://thelazyadmin.com/blogs/thela...erting-Dynamic-Disks-Back-to-Basic-Disks.aspx).

    Do some more tests, figure out what is functional and what is not, doesn't hurt to take a look at it with Linux at all before opening it up. Good luck, my Omega 1TB is also two seperate 500s now and I feel more comfortable having it that way even though I have to keep track of data on two different drives.
     
  12. MattsComp

    MattsComp

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    Sounds good - I'll let you all know. Thanks Fairnooks! I've been really impressed with techguy forums thus far, lots of good info here...
     
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