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Rebuild RAID 5 array

Posted on 2008-10-12
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I just inherited a server on its last legs apparently. There was an amber status light blinking on the number 3 drive indicating some sort of failure. I figured I would wait until scheduled downtime on Wednesday to look into it further, but as Murphy's law would have it, my Kaseya popped up around 12:30AM this morning to let me know that the server was offline. When I went in to take a look at it, the number 0 drive was also blinking amber. I rebooted the server and all of the lights went back to green on the drives, but it showed in the RAID BIOS at boot time that the RAID 5 array was degraded. Fine, I entered the control utility and it said REBUILD 0% on the container. This did not change for about 30 minutes, so I exited out and rebooted. Then drives 3 and 4 had amber lights. I rebooted once more and the drives all went back to normal, but the container shows drives 3 and 4 as missing members.

Normal OS boot is not possible. It tells me that the OS could not be found. Please help.
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Question by:jhalscott
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by:Jeews
ID: 22700394
From your setup utility make the 3 and 4 drives offline first and then re boot and make them online and then re-build the array and try
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by:jhalscott
ID: 22700422
OK, all of the status lights are fine again, but the RAID configuration utility still shows Missing Member for disks 3 and 4 and it cannot find a boot device. I have the Verify Disk running on one of the drives now, but it will take some time. Any other ideas?
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by:lnkevin
ID: 22703074
I am afraid that you may have to rebuild from scatch. Here is the observation:

In RAID 5, if you lose a drive (amber light indication), your RAID5 is still running with degradded status. However, if you lose a second drive in a row (2 drives at a time), your RAID5 is corrupted and not able to rebuild itself.

As of now, you are looking to rebuild, restore from backup after replace the new drives. You need to replace the drives first, rebuild a RAID 5 container and rebuild OS, restore from backup ....

Loosing two drives at a time is rare, but is not impossible. The only suggestion is always replacing your first failed drive as soon as you find out. When RAID is degraded, you don't have redundancy and your data is jeopardized.

K

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lnkevin earned 1500 total points
ID: 22703162
I figured I would wait until scheduled downtime on Wednesday to look into it further....

In Raid5, replacing a failed drive is easy since Dell 2650 drives are hotswapable. All you have to do is pop out a bad drive and insert the new drive while your server is up and running. You then allow 1 -  2 hours for RAID 5 to rebuild itself, do not reboot or disturb when your RAID is rebuilding. Check your Dell Server Manager for the rebuild status. That's it! No need to schedule down time and DON'T replace your drive while the server is off or down. Someone lost their data when brought the server down then replaced the drive and booted it up....

Anyway, this is just some info for the future.

K
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