Thanks, that feels reassuring!
What is the entry "unused devices" in /proc/mdstat?
> By the mdstat shown below, you have a 3 drive raid-5 device with
> one spare. The
> [0], [1] and [2] indicate the raid role for the associated disks.
> Values of [3]
> or higher are the spare (for a three disk array.) In general, in
> an 'n' disk
> raid array, [0]..[n-1] are the disks that are in the array with
> data, and [n]...
> are the spares, as shown from /proc/mdstat.
>
> You are in good shape for the hda2 disk to kick in as the spare
> if on of the
> other disks fails.
>
> <>< Lance.
>
> Johan Ekenberg wrote:
>
> > I recently inquired about adding a spare-disk to an operating
> RAID-5 array,
> > and was given the advice to use raidhotadd. I've tried this and
> want to make
> > sure that the result is the one I should expect. I thought that
> spare disks
> > would show up as an "unused device" in /proc/mdstat, but that
> may not be the
> > case???
> >
> > This is my mdstat:
> > Personalities : [linear] [raid0] [raid1] [raid5]
> > read_ahead 1024 sectors
> > md0 : active raid5 hda2[3] sdc2[2] sdb2[1] sda2[0] 8305408
> blocks level 5,
> > 32k chunk, algorithm 2 [3/3] [UUU]
> > unused devices: <none>
> >
> > The spare disk in this case is hda2[3], defined as a spare in
> /etc/raidtab.
> > Is this the way it should look? Can I be confident that hda2
> will kick in if
> > one of the sd* fails? hda2 is of course formated exactly like the other
> > partitions.
>
