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RAID 1 - Fast Recovery Technique

Ayman Altounji
Valued Contributor

RAID 1 - Fast Recovery Technique

I have been using RAID 1 arrays for somew time now, and quite successfully, as a sort of "cold spare" server recovery technique. Given a server with its system partition on a mirrored (internal) array, the short form of the technique is as follows:
1) Power off the server completely, yank one of the mirrored disks.
2) Power on the server (sans the 'yanked' disk) - and fail the missing drive.
3) Replace the drive with a blank, perform whatever maintenance which may have prompted all these fun activities.
4) In case of diabolical catastrophe, power down completely, yank BOTH mirrored disks, put back the one we pulled to begin with, and power up.

As you can see, this allows for a recovery of the system to a state just prior to whatever silliness you may have gotten up to with the server. The biggest "gotcha!" was when we tried this while an external subsystem was attached to the same array controller (in this case, it was actually on a 3200 and not a 2P). If you try to fail back while something is externally attached, *poof!* - you toast the recovery disk, do not pass go, do not collect $200. Never mind how or why, trust me - he's dead, Jim, and there's no recovery in sight.

OK, easy (if somewhat tedious) workaround: disconnect any subsystems before you try to "recover," and you should be good to go.

Well, this is all fine and good, but now we've hit another snag. I need to use this recovery technique on a couple of older systems - these are Proliant 500R's with the Smart 2-P controllers. Unfortunately for me, ALL the disks are in an external (4U7E) enclosure - four physical disks, 2 mirrored arrays. C:\ and D:\ are the system and utility partitions of array 1, and E:\ is the data volume on array 2. Not entirely surprisingly, trying to "recover" to any previously archived disk results in an entirely familiar "*poof!*" condition, wherein the disk you mortgaged your future hopes and dreams against, becomes -shall we say - less than viable.

Any ideas what might be behind this madness? Please don't tell me I have to migrate the system partition to the internal enclosure...?

- Jason
1 REPLY
Ayman Altounji
Valued Contributor

Re: RAID 1 - Fast Recovery Technique

Oops - typo, that should read "5000R" ... Hehe, you were probably wondering what the heck kind of systems these were? :-)