Thursday, March 01, 2007

3Ware disk copying

I use a number of systems with 3Ware IDE RAID cards. Recently, we had a drive start giving us fits on one of the 3Ware cards. I'm not entirely convinced that the problem was the drive (I'm starting to think it was the power supply or long shot, motherboard), but in the process I discovered that if the drive is still readable, you can do a "dd" from the drive in the array to a new drive, and once complete, the 3Ware card will recognize the new drive as if it were the old drive. Since this was a 1TB RAID0 array, that was a nice option to have rather than rebuild the array from scratch and lose the data on there. Granted, it's RAID0 so the data wasn't critical, but it was nice to get it back nonetheless.

To do this, boot a live Linux CD distro, like Knoppix with the old drive plugged in as the Primary IDE Master and the new drive plugged in as the Secondary IDE Master, run the following:

dd if=/dev/hda of=/dev/hdc

as root. This process will take hours typically, so be patient. If you'd like to track it's progress, suspend the dd process (ctrl-Z), and then tell it resume running in the background (type bg, and then hit enter). Run the command "pidof dd" to get the PID of the dd process. To monitor the process of the disk copy, run "kill -USR1 [PID]", where [PID] is the number returned by "pidof dd".

Once complete, place the new drive in the 3Ware system, and it should show up as part of the original array.


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