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#1 2009-06-05 21:07:10

uppsju
Member
Registered: 2007-12-14
Posts: 18

Question about how JBOD works

Just wondered if JBOD has the same feature as RAID 0 that the data is spread over the physical discs, so that if one disk goes down the whole data is lost?
Or would it be possible to remove one disk from a JBOD setup and insert disk into a computer and transfer the data?

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#2 2009-06-05 22:49:52

fordem
Member
Registered: 2007-01-26
Posts: 1938

Re: Question about how JBOD works

No and probably not in that order.

With JBOD the data is first written to one disk and when that is filled then the other one is used - with RAID0 the data is split into chunks and the chunks written to each disk alternately, so CH#1 on disk0, CH#2 on disk1, CH#3 on disk0, etc.

If you lose a physical disk with RAID0 you lose access to your data, all of it, there and then - if you lose a physical disk with JBOD, depending on which disk you lose and where the data was written, you may still have access to the data.  Let's say you have 2x250GB disks in a JBOD config and you write 100GB of data.  If the first disk fails your data is gone, if the second disk fails your data will still be available - until you reboot the DBS-323, at which point it will become inaccessible.

I have no idea what would happen if you had 400GB of data and the first disk failed - would you still have access to the data on the remaining disk?  I have not tested that scenario, and whilst I will not say that you cannot remove a single disk, place it in a computer and get access to your data, I will say it's not going to be a simple task.

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