extracting data from failed raid 0

  • Thread starter Thread starter RBM
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RBM

Is it possible to extract data from a failed raid 0, and if so, how to go
about it?

tia, rbm
 
RBM said:
Is it possible to extract data from a failed raid 0, and if so, how to go
about it?

tia, rbm
Click to expand...

First, you'd tell us what failed. Did the RAID BIOS report the failure ?
Did you have Windows installed on the RAID0, and booting failed.
Was the RAID a data-only array, and it has simply disappeared from
Windows ? Perhaps the Windows RAID Management software is happy with
the array, except the partition is missing.

The answer for each of those cases could be different.

These are the resources on the RAID0 drives I know about.

One drive has the odd blocks of data 1,3,5.
The other drive has the even blocks of data 2,4,6.

The "block" is some number of sectors of data. Due to that
interleaving pattern, when one drive fails, a recovered file
would have "block" sized holes punched in it. If a file fit
within a block sized chunk, it might be recovered intact.

Each drive has a "reserved sector" (actual size is 512 bytes to
64KB). The reserved sector records the array partnership, which
drive is odd and which drive is even, perhaps even their serial
numbers. There is enough info there, so that if you move the
drives from one SATA connector to another, the driver can still
figure out they're an array. The format of the reserved sector
is not standardized, so you cannot move an Nvidia array to an
Intel controller.

I'm guessing here, but presumably everything above that level
(Windows file system info) would be layered on top of that
interleaved block structure. That means the partition table
might be entirely contained on one of the drives. If the
partition table is erased, the RAID array software should
not be reporting a failure, but you may have noticed the
volume was missing in Windows. And if that was your C: volume that
you boot from, a boot failure may not mean the RAID is
failed either - it could be just the partition table is
damaged. Or some key boot file is missing, and the problem
has little to do with the fact it is a RAID0.

There is a free recovery program here, which might work
in some situations. This doesn't have its own drivers,
and would seem to rely in at least the Windows version,
on the drivers in the system. If the RAID driver won't
make the array "visible", this won't work.

http://www.cgsecurity.org/wiki/TestDisk_Step_By_Step

There are a ton of those $39.95 recovery programs, but
who knows which of them work. There are also data
recovery firms, who would love to charge you $1000
to recover a RAID. So those are other options.

Paul
 
philo said:
Depends on what failed.

If one of the drives has failed, data recovery will essentially be close
to
impossible.

if it was the controller, then yes, you have a chance.

A back-up scheme would have been a *necessity* for Raid 0
Click to expand...

Thanks, that's what I thought. One of the drives did fail
 
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