Data recovery software for failed Raid 5 SCSI arrays

oneilldo

oneilldo

oneilldo

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I was wondering if anyone had any experience of data recovery software for a Raid 5 array where 2 disks have failed.
(The Raid 5 contains 14 SCSI disks). Ideally want some software where the demo shows what files can be recovered and then
the software at a cost copies these files to another SCSI array. A quick google brings up a few choices but I wanted to know
if anyone has done this before and what software they used.

Thanks
Oneilldo
 
tomos said:
not a helpful respond (sorry), but i thought raid-5 would handle a disk or 2 failing out of that many? :confused:
Click to expand...

RAID 5 will cope with 1 drive failing but not 2, personally I wouldn't go for an array that big without at least one hot spare drive.

Anyhoo back to the original question - I doubt that there is any way back, at best you'll be able to recover 12/13ths of each file and you don't have enough parity information to recover the missing data.
 
Tommer said:
think you'll find its raid 6 thats caters for 2 drive failures
Click to expand...

Correct.

Yup RAID5 means that your data is striped over the drives (as is the parity). Loss of two drives means one big headache for recovery unfortunately. In short that sounds like a complete loss.

My RAID5 array has a hot swap drive that will automatically rebuild to if one drive fails. Not the same as RAID6 but RAIDing is about availability rather than backup.
 
RAID 10 can also offer double drive failure protection.

You must be really unlucky to lose two drives in the same RAID 5 group (unless the group is huge, like 15 disks).
 
The disks were for recoverable data anyway so not really a problem.
The array was a 14 disk Raid 5 array.
The array didn't have any hot spare configured but wouldn't have helped anyhow. Basically we are currently installing new UPS's onto most of the servers and had a power glitch. The server was on UPS but the array wasn't. When the array came back on line two disks were showing as failed (hence hot swappable not being much use). Managed to reseat both (then only one was showing as failed), then rebuilt that drive and all is fine.

Out of curisoity how many drives could you 'safely' lost in say a 10 disk RAID 10 setup.
 
oneilldo said:
Out of curisoity how many drives could you 'safely' lost in say a 10 disk RAID 10 setup.
Click to expand...
1 - as raid 10 is just a striped array that has been mirrored each side of the mirror has no redundancy in itself.

The first drive to fail would knock out the mirror that contained it leaving just a single raid 0 striped array.
 
So basically if two disks went in any Raid 10 setup you would be screwed.
If I am getting this then if you had a 10disk raid 10 array 5 disks contain the 'usable' data which is striped across them, the other 5 disks contain the mirror of the data so if two disks went you would be in trouble?
 
oneilldo said:
So basically if two disks went in any Raid 10 setup you would be screwed.
If I am getting this then if you had a 10disk raid 10 array 5 disks contain the 'usable' data which is striped across them, the other 5 disks contain the mirror of the data so if two disks went you would be in trouble?
Click to expand...
Yep.

When any drive in a RAID 0 array breaks the whole array becomes completely inoperative.

The first drive to expire disables the mirror leaving a single 5 disk raid 0 array, so no redundancy left.

This page has some nice pictures of the different arrays
http://www.pantherproducts.co.uk/Articles/Storage/RAID.shtml
 
Thanks,

You had me confused then as I was sure you can safely lose more than 1 in raid 10 (well it will still work if you lost 2 drives depending on the drives)
 
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