Richard Scobie wrote:
Have a look at the "Grow Mode" section of the mdadm man page.
Thanks! I overlooked that, although I did look at the man page before
posting.
It looks as though you should just need to use the same command you
used to grow it to 3 drives, except specify only 2 this time.
I think I hot-added it. Anyway, --grow looks like what I need, but I'm
having some difficulty with it. The man page says, "Change the size or
shape of an active array." But I got:
[root@samue ~]# mdadm --grow /dev/md5 -n2
mdadm: Cannot set device size/shape for /dev/md5: Device or resource busy
[root@samue ~]# umount /dev/md5
[root@samue ~]# mdadm --grow /dev/md5 -n2
mdadm: Cannot set device size/shape for /dev/md5: Device or resource busy
So I tried stopping it, but got:
[root@samue ~]# mdadm --stop /dev/md5
[root@samue ~]# mdadm --grow /dev/md5 -n2
mdadm: Cannot get array information for /dev/md5: No such device
[root@samue ~]# mdadm --query /dev/md5 --scan
/dev/md5: is an md device which is not active
/dev/md5: is too small to be an md component.
[root@samue ~]# mdadm --grow /dev/md5 --scan -n2
mdadm: option s not valid in grow mode
Am I trying the right thing, but running into some limitation of my
version of mdadm or the kernel? Or am I overlooking something
fundamental yet again? md5 looked like this in /proc/mdstat before I
stopped it:
md5 : active raid1 hdc8[2] hdg8[1]
58604992 blocks [3/2] [_UU]
For -n the man page says, "This number can only be changed using --grow
for RAID1 arrays, and only on kernels which provide necessary support."
Grow mode says, "Various types of growth may be added during 2.6
development, possibly including restructuring a raid5 array to have
more active devices. Currently the only support available is to change
the "size" attribute for arrays with redundancy, and the raid-disks
attribute of RAID1 arrays. ... When reducing the number of devices in
a RAID1 array, the slots which are to be removed from the array must
already be vacant. That is, the devices that which were in those slots
must be failed and removed."
I don't know how I overlooked all that the first time, but I can't see
what I'm overlooking now.
mdadm - v1.6.0 - 4 June 2004
Linux 2.6.12-1.1381_FC3 #1 Fri Oct 21 03:46:55 EDT 2005 i686 athlon i386
GNU/Linux
Cheers,
11011011
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