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recovering from broken mirror

Posted on 2004-08-09
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Last Modified: 2010-04-14
HI,

I would like to recover a server with a mirror that was already broken before the crash.
Does somebody know what is the exact difference between a broken mirror and an operational mirror and how you can boot from an mirror that was broken before a crash?

Niels
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Question by:robertoballo
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dlwyatt82 earned 168 total points
ID: 11756252
This will depend partially on your RAID implementation (ie, are you running Windows software RAID, or do you have a hardware controller?), but as a general rule, if a RAID 1 (mirror) set is failed or broken, you can treat the remaining functional drive as a single standalone disk until you repair the RAID mirror.

For recovery purposes, just try to recover the disk that was working before the crash, and ignore the other until afterwards.
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by:dis1931
dis1931 earned 166 total points
ID: 11756259
Operational Mirror means you have at least two drives that contain the exact same contents.  If you save data it gets replicated on both drives.  If a mirror is purposely broken then the mirroring stops and you have two seperate hard drives.  If a hard drive fails, you would break the mirror and then replace the drive and recreate the mirror so that the working drive can mirror itself to the new drive.  If you broke the mirror and then the PC crashed you basically boot off the one drive in the mirror.  If you had the mirror working and a hard drive failed it would be fault tolerant and would use the working drive,  Is this what you wanted to know?
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by:dlwyatt82
ID: 11756343
As a clarification, I got the impression that you had a RAID mirror working at some point, then a drive failed, and you left it broken for a period of time. Then you had some sort of system crash (for any reason) while the mirror was still in the broken state, and want to know how to recover your data... if that is accurate, then my my initial comments still apply.
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by:Paka
Paka earned 166 total points
ID: 11756613
Do you have a software or hardware mirror.  If it is a software mirror, you'll probably need to modify your boot.ini to point to the other partition depending on which copy of the mirror failed.  If it is a hardware mirror, fix the OS problems (if it is a crash) and then use the hardware controller features to rebuild.
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