Neil Brown wrote:
>On Wednesday January 18, cizek@xxxxxxx wrote:
>
>>Hi,
>>
>>Are there any known issues with changing the number of active devices in
>>a RAID1 array?
>
>
>There is now, thanks.
>
>>I'm trying to add a third mirror to an existing RAID1 array of two disks.
>>
>>I have /dev/md5 as a mirrored pair of two 40 GB disks. Directly on top
>>of it is a 40 GB XFS filesystem.
>>
>>When I do "mdadm --grow /dev/md5 -n 3" the count of devices changes from
>>2 to 3, as expected.
>>If the XFS filesystem is mounted, the array size changes to 3.0 GB.
>>If it is not mounted everything works fine.
>>
>>Is this supposed to work, is it required that the array be inactive to
>>add a disk, or am I just doing
>>something stupid?
>
>
>It is supposed to work, it doesn't, but it is the code doing something
>stupid, not you.
>Try the patch below.
>
[snip]
The patch you gave me worked, Neil, but the I ran into an odd problem where
the change is lost after a reboot.
I have raid1 devices for both superblocks 0.90.? and 1.0
If I update the superblock 1.0 device, mdadm --detail shows the update,
but if I reboot it is lost.
As well, evms complains about a mismatch between the kernel and disk
(this is how I first noticed it).
Superblock 0.90 works fine.
i.e. Starting with /dev/md4, superblock 1.0 with 2 devices:
mdadm --detail /dev/md4 shows
Raid Devices : 2
Active Devices : 2
I do "mdadm --grow /dev/md4 -n3"
mdadm --detail /dev/md4 shows
Raid Devices : 3
Active Devices : 2
I reboot....
mdadm --detail /dev/md4 shows
Raid Devices : 2
Active Devices : 2
Hope this makes sense.
Thanks,
-Bill
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