I'm not sure whether this is a RAID problem or an LVM problem. I'll
start here since I can see more weird things happening with RAID than
LVM at the moment.
I have a Debian testing system running on a Sun box (2 x 400 MHz
Ultrasparc II processors). There are currently three 18G SCSI drives in
it: sda (not used), sdb and sdc (both of which have root partitions of
500M, and the remainder (sd[bc]4)combine to make up md0, a RAID-1
array. This has LVM2 on it to make up the /usr, /home and /var
partitions. Originally there was also an external SCSI disk drive tower,
and I'd used two drives of it in md0 to form another partition.
Everything ran OK until a week or so ago when I needed to turn the
machine off overnight. Before I brought it up the next morning, I
disconnected the external tower since I wasn't using it and it was
making a lot of noise. When I booted the box, LVM wouldn't start the
volume group because the other two drives were missing. After clearing
that one up, eventually, I could mount the VG, but LVM gave this error:
> Found duplicate PV xxxxxxxxxxxxxxxx: using /dev/sdc4 not /dev/sdb4
I couldn't seem to fix this. Eventually I gave up, copied the data
to another drive, deleted the VG, stopped the array, zeroed the
superblocks on the drives, and rebuilt the whole thing. Here's what I
get when I boot the system:
> input: Sun mouse on su/serio0
> md: linear personality registered as nr 1
> md: raid1 personality registered as nr 3
> md: raid5 personality registered as nr 4
> raid5: measuring checksumming speed
> VIS: : 120.000 MB/sec
> raid5: using function: VIS (120.000 MB/sec)
> md: md driver 0.90.1 MAX_MD_DEVS=256, MD_SB_DISKS=27
> device-mapper: 4.4.0-ioctl (2005-01-12) initialised: dm-devel@xxxxxxxxxx
>
> (5 lines of net-related stuff)
>
> md: Autodetecting RAID arrays.
> md: autorun ...
> md: ... autorun DONE.
> kjournald starting. Commit interval 5 seconds
>
> ...
>
> All modules loaded.
> Creating device-mapper devices...done.
> Creating device-mapper devices...done.
> Setting up LVM Volume groups...
> Reading all physical volumes. This may take a while...
> Found duplicate PV tS784Ip4IRpt8EwL84tETKpe1H4A11IG: using
/dev/sdc4 not /dev/sdb4
> Found volume group "curly_vg" using metadata type lvm2
> Found duplicate PV tS784Ip4IRpt8EwL84tETKpe1H4A11IG: using
/dev/sdc4 not /dev/sdb4
> 3 logical volume(s) in volume group "curly-vg" now active
So I still have the "Found duplicate" problem. A little more poking
around with mdadm made me wonder whether the RAID array is working at
all. I get conflicting results.
/proc/mdstat has this:
> Personalities : [linear] [raid1] [raid5]
> unused devices: <none>
mdadm -Q /dev/md0 gets me:
> /dev/md0: is an md device which is not active
> /dev/md0: is too small to be an md component.
mdadm -Q /dev/sdb4 gets me:
> /dev/sdb4: is not an md array
> /dev/sdb4: device 0 in 2 device undetected raid1 md0. Use mdadm
--examine for more detail.
mdadm -Q /dev/sdc4 gets me:
> /dev/sdc4: is not an md array
> /dev/sdc4: device 1 in 2 device undetected raid1 md0. Use mdadm
--examine for more detail.
mdadm -D /dev/md0 has:
> mdadm: md device /dev/md0 does not appear to be active.
On the other hand, mdadm --examine /dev/sdb4 gets me:
> /dev/sdb4:
> Magic : a92b4efc
> Version : 00.90.00
> UUID : a138d961:627a9a93:d92158f3:f4e786e0
> Creation Time : Mon Jun 20 11:43:17 2005
> Raid Level : raid1
> Raid Devices : 2
> Total Devices : 2
> Preferred Minor : 0
>
> Update Time : Mon Jun 20 13:07:57 2005
> State : clean
> Active Devices : 2
> Working Devices : 2
> Failed Devices : 0
> Spare Devices : 0
> Checksum : 1567d8d - correct
> Events : 0.12756
>
>
> Number Major Minor RaidDevice State
> this 0 8 20 0 active sync
/dev/.static/dev/sdb4
>
> 0 0 8 20 0 active sync
/dev/.static/dev/sdb4
> 1 1 8 36 1 active sync
/dev/.static/dev/sdc4
and mdadm --examine /dev/sdc4:
> /dev/sdc4:
> Magic : a92b4efc
> Version : 00.90.00
> UUID : a138d961:627a9a93:d92158f3:f4e786e0
> Creation Time : Mon Jun 20 11:43:17 2005
> Raid Level : raid1
> Raid Devices : 2
> Total Devices : 2
> Preferred Minor : 0
>
> Update Time : Mon Jun 20 13:07:57 2005
> State : clean
> Active Devices : 2
> Working Devices : 2
> Failed Devices : 0
> Spare Devices : 0
> Checksum : 1567d9f - correct
> Events : 0.12756
>
>
> Number Major Minor RaidDevice State
> this 1 8 36 1 active sync
/dev/.static/dev/sdc4
>
> 0 0 8 20 0 active sync
/dev/.static/dev/sdb4
> 1 1 8 36 1 active sync
/dev/.static/dev/sdc4
The results of mdadm --examine --scan are:
> ARRAY /dev/md0 level=raid1 num-devices=2
UUID=a138d961:627a9a93:d92158f3:f4e786e0
> devices=/dev/sdc4,/dev/sdb4
and the contents /etc/mdadm/mdadm.conf are:
> DEVICE /dev/sd*[0-9]
> ARRAY /dev/md0 level=raid1 num-devices=2
UUID=3570b3b2:58eaa1de:4064ed19:b8b2607b
mdadm version is 1.9.0, and I'm running kernel 2.6.11.
I suspect that the RAID array isn't working, and that LVM has picked
one of the two disks and is using that. Is that likely? What do I need
to do at this point?
Thanks,
.....Ron
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