Is my raid-1 array working?

Is my raid-1 array working?

[Ron Murray]

    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@redhat.com
 >
 >  (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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Re: Is my raid-1 array working?

[Luca Berra]

On Tue, Jun 21, 2005 at 09:21:49AM -0400, Ron Murray wrote:
> > Found duplicate PV xxxxxxxxxxxxxxxx: using /dev/sdc4 not /dev/sdb4

check that you have 
    md_component_detection = 1

in /etc/lvm/lvm.conf

L.

-- 
Luca Berra -- bluca@comedia.it
        Communication Media & Services S.r.l.
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Re: Is my raid-1 array working?

[Ron Murray]

Jurriaan Kalkman wrote:
>> > md: Autodetecting RAID arrays.
>> > md: autorun ...
>> > md: ... autorun DONE.
> 
> 
> Since no partitions seem to be recognized here, my first question would
> be: are the partitions of type 0xfd - the one you need for them to be
> automatically recognized?
> 
> Kind regards,
> Jurriaan


Aaaaahhhhhhhhhhhhhhh!!!! That fixed it. I must have missed that part.

Thanks for the help.

  .....Ron

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This email and any files transmitted with it are confidential and 
intended solely for the use of the individual or entity to whom they   
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the system manager at postmaster at dor.state.ma.us.
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