data recovery from raid5 drives
I was recently charged with increasing the storage of a linux file server. Seemed simple enough at first, I figured it could be done in an evening without too much effort. Then I found out that the megaraid controller wasn't recognized by any bootable CD I had. The particular raid controller is an American Megatrends Megaraid version 02.
In the end, with a current debian testing image, I did get the system running with three new drives in a raid5 array, and I did do it in the evening I had alloted for it. But when I went back to install the machine the next day, I discovered I had not copied all the files I needed to before I took the old drives out, and the machine was back in production, so I couldn't exactly shut it down and put the old drives in. Besides, even if I had done that, I am not sure that the megaraid controller would see the old raided drives, now that the controller has been reconfigured with the new drives.
I figured I could use software raid to recreate the array, and after some poking around, I did find a few posts on people who had used that trick for a raid0 and raid1 config, and one who had used his skills as a java programmer in conjunction with gnu/linux to recover a raid5 of 5 disks.
I have the drives in a machine and have booted up with the gparted live cd, but nothing really seems to be functioning the way I had hoped. /dev/hda-b-c are the three drives, /dev/hdd is the cd. querying the drives with madam -Q tells me /dev/hd* is not an md array, and mdadm --examine tells me there is no md superblock detected on any disc, or any partition thereof. parted tells me /dev/hda and /dev/hdb have paritions outside of the disk, and /dev/hdc is an unrecognized disc label. ls /dev/hd* seems to indicate there are 4 partitions on hda and hdb, but no partitions on hdc.
I have perused the man page for mdadm, and do not see any other options for recovering the array this way.
So now, while I am doing this post, I am also looking for documentation on the particular raid controller to see if I can put the drives back in the original machine without danger of losing the data. But I am hoping somebody has some other ideas for me to try using mdadm or some other piece of software available to the linux world...
All comments appreciated...