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Lord_Devi 05-30-2008 08:24 PM

RAID Repair after renamed devices
Hello all.

Rather new to software linux raid, I have encountered my first problem. It seems simple to me on the surface, however I am not sure how to actually go about fixing the problem. To make it short, my RAID 5 array consisted of 3 devices. After popping a new HD into the computer the array is on, some of the devices were renamed(the /dev devices) and the array is no longer assembling properly. I was hoping that simply editing my mdadm.conf to represent these changes would be enough - but I guess I am not that lucky.

The basic layout of my RAID array before the problem:

/dev/md0 consisted of sdb1, sdc1, and sdd1.

After installing a new SATA drive the devices were changed, and I am not exactly sure in what order(I could use fdisk disk id's to determine this by unplugging the new hd and restoring the old setup I suppose if I need the information to reassemble it in order tho). But now I have no more sdd1. Instead one of the array elements is now sda1.

So before:
sdb1, sdc1, sdd1
sda1, sdb1, sdc1

Essentially I need to tell mdadm where that 3rd device (sdd1) went and to look at sda1 instead. However I hesitate to do anything myself like --remove and --add until I know exactly what is going on and that my data will be safe.

How do I reassemble this raid, and is there anything important I should keep in mind when fixing this?

zsolt_tuser 05-30-2008 10:48 PM

Try with:

mdadm -A --scan

If it does not work try with:

mdadm -A /dev/md0 /dev/sda1 /dev/sdb1 /dev/sdc1

Lord_Devi 05-30-2008 11:21 PM

Thanks for the reply.

Neither of those do the trick for me though. Both options assemble the array with only sdb1 and sdc1. No sda1 yet.

Any other options?

zsolt_tuser 05-31-2008 05:32 AM

What's the error mesaage? And does the array work with this 2 drives (sdb1 and sdc1)? What's the output of:

mdadm -D /dev/md0

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