On Mon, 28 May 2012 22:50:03 +0200 Oliver Schinagl <oliver+list@xxxxxxxxxxx>
wrote:
> Hi list,
>
> I'm sorry if this is the wrong place to start, but I've been quite lost
> as to what is going wrong here.
No, you are in exactly the right place!
>
> I've been having some issues latly with my raid10 array. First some info.
>
> I have three raid10 arrays on my gentoo box on 2 drives using GPT.
> I was running 3.2.1 at the time but have 3.4.0 running at the moment.
> mdadm - v3.2.5 - 18th May 2012
>
>
> md0, a 2 far-copies, 1.2 metadata, raid10 array consisting of /dev/sda4
> and sdb4.
> md1, a 2 offset-copies, 1.2 metadata, raid10 array consisting of
> /dev/sda5 and sdb5
> md2, a 2 offset-copies, 1.2 metadata, raid10 array consisting of
> /dev/sda6 and sdb6
I'm liking the level of detail you are providing - thanks.
>
> sd*1 is bios_grub data, sd*2 is 256mb fat for playing with uefi and sd*3
> is 8gigs of unused space, may have some version of ubuntu on it and sd*7
> for swap.
>
> For all of this, md0 has always worked normally. it is being assembled
> from initramfs where a static mdadm lives as such:
> /bin/mdadm -A /dev/md0 -R -a md /dev/sda4 /dev/sdb4 || exit 1
In general I wouldn't recommend this. Names of sd devices change when
devices are removed or added, so this is fragile. It may cause the actual
problems you have been experiencing currently.
>
> md1 and md2 are being brought up during boot, md0 holds root, /usr etc
> wheras md1 are just for home and data.
>
> The last few weeks md1 and md2 randomly fail to come up properly. md1 or
> md2 come up as inactive and one of the two drivers are marked as spares.
> (Why as spares? Why won't it try to run the array with a missing drive?)
> While this happens, it's completly abitrary whether sda or sdb is being
> used. so md1 can be sda5[2](S) and md2 can be sdb5[2](S).
The (S) is a bit misleading here. When an array is 'inactive', all devices
are marked as '(S)', because they are not currently active (nothing is as the
whole array is inactive).
When md1 has sda5[2](S), is sdb5 mentioned for md1 as well, or is it simply
absent. I'm guessing the second.
This it most likely caused by "mdadm -I" being run by udev on device
discovery. Possibly it is racing with an "mdadm -A" run from a boot script.
Have a look for a udev/rules.d script which run mdadm -I and maybe disable it
and see what happens.
>
> When this happens, I mdadm --stop /dev/md1 and /dev/md2, followed
> immediatly by mdadm -A /dev/md1 (using mdadm.conf which doesn't even
> list the devices. ARRAY /dev/md1 metadata=1.2 UUID=nnn name=host:home).
> The arrays come up and work just fine.
>
> What happend today however, is that md2 again does not come up, and
> sda6[3](S) shows in /proc/mdadm. However re-assembly of the array fails
> and only using mdadm -A /dev/md2 /dev/sda6 /dev/sdb6 shows:
> mdadm: device 1 in /dev/md2 has wrong state in superblock, but /dev/sdb6
> seems ok
> mdadm: /dev/md2 assembled from 0 drives and 2 spares - not enough to
> start the array.
> /proc/mdadm shows as somewhat expected.
> md2 : inactive sda6[3](S) sdb6[2](S)
>
> Only using sdb6 however also fails. I guess because it does not want to
> use a spare.
> mdadm: failed to RUN_ARRAY /dev/md2: Invalid argument
> mdadm: Not enough devices to start the array.
>
> Now the really disturbing part comes from mdadm --examine.
> valexia oliver # mdadm --examine /dev/sda6
> /dev/sda6:
> Magic : a92b4efc
> Version : 1.2
> Feature Map : 0x0
> Array UUID : nnnn
> Name : host:opt (local to host host)
> Creation Time : Sun Aug 28 17:46:27 2011
> Raid Level : -unknown-
> Raid Devices : 0
>
> Avail Dev Size : 456165376 (217.52 GiB 233.56 GB)
> Data Offset : 2048 sectors
> Super Offset : 8 sectors
> State : active
> Device UUID : nnnn
>
> Update Time : Mon May 28 20:52:35 2012
> Checksum : ac17255 - correct
> Events : 1
>
>
> Device Role : spare
> Array State : ('A' == active, '.' == missing)
>
> sdb6 lists identical content only with the checksum's being correbt,
> albeit different and of coruse the Device UUID. Array UUID is of course
> identical as is creation time.
>
> Also to note, is that grub2 does mention an 'error: Unsupported RAID
> level: -1000000.' which probably relates to the 'Raid Level: -unknown-'.
>
> As to what may have caused this? I have absolutely no idea. I did a
> clean shutdown where the arrays get cleanly unmounted. Not 100% sure if
> the arrays get --stopped but I would be surprised if they did not.
>
> So I guess is this a md driver bug? Is there anything I can do to
> recover my data, which i cannot image it not being?
This is a known bug which has been fixed. You are now running 3.4 so are
safe from it.
You can recover your data by re-creating the array.
mdadm -C /dev/md2 -l10 -n2 --layout o2 --assume-clean \
-e 1.2 /dev/sda6 /dev/sdb6
Check that I have that right - don't just assume :-)
when you have created the array, check that the 'Data Offset' is still
correct, then if it is "fsck -n" the array to ensure everything looks good.
Then you should be back in business.
NeilBrown
>
> Thanks in advance for reading this.
>
> Oliver
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