[dm-devel] Re: raid failure and LVM volume group availability

[Goswin von Brederlow <goswin-v-b web de>]

hank peng <pengxihan gmail com> writes:

> Only one of disks in this RAID1failed, it should continue to work with
> degraded state.
> Why LVM complained with I/O errors??

That is because the last drive in a raid1 can not fail:

md9 : active raid1 ram1[1] ram0[2](F)
      65472 blocks [2/1] [_U]

# mdadm --fail /dev/md9 /dev/ram1
mdadm: set /dev/ram1 faulty in /dev/md9

md9 : active raid1 ram1[1] ram0[2](F)
      65472 blocks [2/1] [_U]

See, still marked working.

MfG
        Goswin

PS: Why doesn't mdadm or kernel give a message about not failing?