On 05/10/06, Nigel Kendrick <support-lists at petdoctors.co.uk> wrote: > > [root at petdoctors ~]# mdadm /dev/md1 -a /dev/hdg3 > mdadm: hot add failed for /dev/hdg3: Invalid argument > [root at petdoctors ~]# I don't know md at all well, but from a quick RTFM, has the previous, faulty /dev/hdg3 been removed from the software RAID device? http://unthought.net/Software-RAID.HOWTO/Software-RAID.HOWTO-6.html#ss6.3 <------------------------------------------------------------------------> Users of mdadm can run the command # mdadm --detail /dev/md1 Now you've seen how it goes when a device fails. Let's fix things up. First, we will remove the failed disk from the array. Users of mdadm can run the command # mdadm /dev/md1 -r /dev/sdc2 Now we have a /dev/md1 which has just lost a device. This could be a degraded RAID or perhaps a system in the middle of a reconstruction process. We wait until recovery ends before setting things back to normal. So the trip ends when we send /dev/sdc2 back home. As usual, you can use mdadm instead of raidtools. This should be the command # mdadm /dev/md1 -a /dev/sdc2 As the prodigal son returns to the array, we'll see it becoming an active member of /dev/md1 if necessary. If not, it will be marked as an spare disk. That's management made easy. <------------------------------------------------------------------------> Will.