on 10/8/2007 6:03 AM Tony Mountifield spake the following:
In article 47098D7B.9020104@gmail.com, Les Mikesell lesmikesell@gmail.com wrote:
The only tricky part is what happens to the drive names if you boot with /dev/sda broken (depending on the failure mode) or missing. If the controller doesn't see it, all of the other drive names will shift up. This normally won't affect md device detection, but you may have a non md device mentioned in /etc/fstab, especially for swap devices.
I normally put swap on a /dev/mdN device too. I have seen different people say you should and you shouldn't, but my reasoning is this: if I have swap just on raw partitions, e.g. /dev/sda2 and /dev/sdb2, what happens if a drive dies while running programs are partly swapped out to the failed drive? I expect at least that the programs would die, and at worst I might get a kernel panic.
But if I am swapping to /dev/md2 that contains /dev/sda2 and /dev/sdb2 in a RAID1 mirror, the swapped-out data is preserved on a drive failure, and the programs should be able to keep running.
Swapping to /dev/mdN certainly seems to work fine, but I haven't yet had a drive failure to test!
Cheers Tony
When I use software raid I always use a mirrored swap partition. It is a little slower, but if you lose a drive, the system won't boink. Otherwise, the system will panic if it can't get back from the swap. Of course the best way it to have enough memory that you don't need swap.