[Bug 20949] New: mdadm cannot assemble array as cannot open drive with O_EXCL

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http://bugzilla.ubuntu.com/show_bug.cgi?id=20949
Ubuntu | kernel-package

           Summary: mdadm cannot assemble array as cannot open drive with
                    O_EXCL
           Product: Ubuntu
           Version: unspecified
          Platform: i386
        OS/Version: other
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: kernel-package
        AssignedTo: ben.collins at ubuntu.com
        ReportedBy: hvy4-idbo at dea.spamcon.org
         QAContact: kernel-bugs at lists.ubuntu.com


Further to discussions (well, monologue!) on the forums here - http://ubuntuforums.org/
showthread.php?p=563255&posted=1

I've had two raid arrays working on my Breezy machine for several months.

/dev/md0 is a raid 5 built from /dev/sd[a-d]
/dev/md1 is a raid 0 built from /dev/sd[e-h]

I rebooted the server so I could change the power leads around and /dev/md1 won't assemble - it 
says no drives.  I have recently done a dist-upgrade and don't recall if I rebooted afterwards. 
/dev/md0 is working fine.

---------------------------------------------------
Here is what I get if I try manually -
sudo mdadm --assemble /dev/md1 /dev/sd[e-h]
mdadm: cannot open device /dev/sde: Device or resource busy
mdadm: /dev/sde has no superblock - assembly aborted

---------------------------------------------------
But --examine is happy with all the drives that make up the array
sudo mdadm --examine /dev/sde
/dev/sde:
Magic : a92b4efc
Version : 00.90.01
UUID : 22522c98:40ff7e71:c16d6be5:d6401d24
Creation Time : Fri May 20 13:56:01 2005
Raid Level : raid0
Device Size : 293036096 (279.46 GiB 300.07 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 1

Update Time : Fri May 20 13:56:01 2005
State : active
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Checksum : 3abea2a9 - correct
Events : 0.1

Chunk Size : 64K

Number Major Minor RaidDevice State
this 3 8 112 3 active sync /dev/sdh

0 0 8 64 0 active sync /dev/sde
1 1 8 80 1 active sync /dev/sdf
2 2 8 96 2 active sync /dev/sdg
3 3 8 112 3 active sync /dev/sdh

The array definitely doesn't exist as this shows -
cat /proc/mdstat
Personalities : [raid5]
md0 : active raid5 sda[3] sdb[2] sdd[1] sdc[0]
732595392 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU]

unused devices: <none>

---------------------------------------------------
More info from using strace

open("/dev/sde", O_RDONLY|O_EXCL) = -1 EBUSY (Device or resource busy)
write(2, "mdadm: cannot open device /dev/s"..., 60mdadm: cannot open device /dev/sde: Device or 
resource busy
) = 60
write(2, "mdadm: /dev/sde has wrong uuid.\n", 32mdadm: /dev/sde has wrong uuid.
) = 32

It looks like the exclusive open to sde is failing. I tried using lsof to see what else had sde 
open but can't see anything.

All ideas welcome, but I'm really worried that I might do something to get my /dev/md0 array 
into the same state, and this is required 24x7.

Note that this machine has been upgraded from Hoary, and I've also renumbered the mdadm-raid 
script in /etc/rcS.d as with it in the default place it was running before hotplug.

I'm reporting this as a kernel-package bug as I really don't know where else to put it!

Thanks

Ian

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