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January 15, 2003

Replacing Bad Disk in Disk Mirror

For the past two years I've relied heavily on a consultant when it came to Sun hardware. Recently we had a disk go bad in our webserver and for whatever reason I felt inspired to tackle the project myself. The most intimidating piece of the puzzle was the disk mirroring. Primarily because I hadn't used Sun's DiskSuite before. In hindsite there isn't much to the DiskSuite, a little knowledge reduced all uncertainty.

I should also say that my understanding of DiskSuite is that the disks must be identical, down to the exact number of cylinders. I couldn't find an exact match for the bad disk, so I was required to install two new disks, which actually seemed to make the process easier. We use an external MultiPack to house the data (non boot) disks.

I was suprised at how clear and navigable the Sun docs were for Solstice DiskSuite. I couldn't find them with a search on the sunsolve page (which supports this recommendation), but a Google search turned them right up (and yes, they were in the sunsolve site).

Here was my process:
1. Unmount the metadevice
2. Break and remove the DiskQuite mirror (metadetach <mirror> <submirror>)
3. Alter /etc/vfstab to point at the one existing good disk
4. Shut down machine
5. Install two new disks
6. Bring up machine
7. Format new disks
6. newfs new disks
7. create new metadevice and submirrors (wait for resync)
8. mount up md
9. sudo ufsdump 0f - /dev/rdsk/c1t6d0s0 | (cd /datanew; sudo ufsrestore xf -)
10. Alter /etc/vfstab to point at metadevice
11. Shut down machine
12. Pull old disk pair (marking bad one)
13. Bring up machine

Posted by mike at January 15, 2003 7:46 AM