Justin Piszcz wrote:
On Sun, 14 Dec 2008, nterry wrote:
Michal Soltys wrote:
nterry wrote:
Hi. I hope someone can tell me what I have done wrong. I have a 4
disk Raid 5 array running on Fedora9. I've run this array for 2.5
years with no issues. I recently rebooted after upgrading to
Kernel 2.6.27.7. When I did this I found that only 3 of my disks
were in the array. When I examine the three active elements of the
array (/dev/sdd1, /dev/sde1, /dev/sdc1) they all show that the
array has 3 drives and one missing. When I examine the missing
drive it shows that all members of the array are present, which I
don't understand! When I try to add the missing drive back is says
the device is busy. Please see below and let me know what I need
to do to get this working again. Thanks Nigel:
==================================================================
[root@homepc ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdd1[0] sdc1[3] sde1[1]
735334656 blocks level 5, 128k chunk, algorithm 2 [4/3] [UU_U]
md_d0 : inactive sdb[2](S)
245117312 blocks
unused devices: <none>
[root@homepc ~]#
For some reason, it looks like you have 2 raid arrays visible - md0
and md_d0. The latter took sdb (not sdb1) as its component.
sd{c,d,e}1 is in assembeld array (with appropriately updated
superblocks), thus mdadm --examine calls show one device as removed,
but sdb is part of another inactive array, and the superblock is
untouched and shows "old" situation. Note that 0.9 superblock is
stored at the end of the device (see md(4) for details), so its
position could be valid for both sdb and sdb1.
This might be an effect of --incremental assembly mode. Hard to tell
more without seeing startup scripts, mdadm.conf, udev rules,
partition layout... Did upgrade involve anything more besides kernel ?
Stop both arrays, check mdadm.conf, assemble md0 manually (mdadm -A
/dev/md0 /dev/sd{c,d,e}1 ), verify situation with mdadm -D. If
everything looks sane, add /dev/sdb1 to the array. Still, w/o
checking out startup stuff, it might happen again after reboot.
Adding DEVICE /dev/sd[bcde]1 to mdadm.conf might help though.
Wait a bit for other suggestions as well.
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I don't think the Kernel upgrade actually caused the problem. I
tried booting up on an older (2.6.27.5) kernel and that made no
difference. I checked the logs for anything else that might have
made a difference, but couldn't see anything that made any sense to
me. I did note that on an earlier update mdadm was upgraded:
Nov 26 17:08:32 Updated: mdadm-2.6.7.1-1.fc9.x86_64
and I did not reboot after that upgrade
I included my mdadm.conf with the last email and it includes ARRAY
/dev/md0 level=raid5 num-devices=4
devices=/dev/sdb1,/dev/sdc1,/dev/sdd1,/dev/sde1
My configuration is just vanilla Fedora9 with the mdadm.conf I sent
I've never had a /dev/md_d0 array, so that must have been
automatically created. I may have had other devices and partitions
in /dev/md0 as I know I had several attempts at getting it working
2.5 years ago, and I had other issues when Fedora changed device
naming, I think at FC7. There is only one partition on /dev/sdb, see
below:
(parted) select /dev/sdb Using /dev/sdb
(parted) print Model: ATA Maxtor 6L250R0 (scsi)
Disk /dev/sdb: 251GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Number Start End Size Type File system Flags 1
32.3kB 251GB 251GB primary boot, raid
So it looks like something is creating the /dev/md_d0 and adding
/dev/sdb to it before /dev/md0 gets started.
So I tried:
[root@homepc ~]# mdadm --stop /dev/md_d0
mdadm: stopped /dev/md_d0
[root@homepc ~]# mdadm --add /dev/md0 /dev/sdb1
mdadm: re-added /dev/sdb1
[root@homepc ~]# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdb1[4] sdd1[0] sdc1[3] sde1[1]
735334656 blocks level 5, 128k chunk, algorithm 2 [4/3] [UU_U]
[>....................] recovery = 0.1% (299936/245111552)
finish=81.6min speed=49989K/sec
unused devices: <none>
[root@homepc ~]#
Great - All working. Then I rebooted and was back to square one with
only 3 drives in /dev/md0 and /dev/sdb in /dev/md_d0
So I am still not understanding
where /dev/md_d0 is coming from and although I know how to get things
working after a reboot, clearly this is not a long term solution...
What does:
mdadm --examine --scan
Say?
Are you using a kernel with an initrd+modules or is everything
compiled in?
Justin.
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[root@homepc ~]# mdadm --examine --scan
ARRAY /dev/md0 level=raid5 num-devices=2
UUID=c57d50aa:1b3bcabd:ab04d342:6049b3f1
spares=1
ARRAY /dev/md0 level=raid5 num-devices=4
UUID=50e3173e:b5d2bdb6:7db3576b:644409bb
spares=1
ARRAY /dev/md0 level=raid5 num-devices=4
UUID=50e3173e:b5d2bdb6:7db3576b:644409bb
spares=1
[root@homepc ~]#
I'm not sure I really know the answer to your second question. I'm
using a regular Fedora9 kernel, so I think that is initrd+modules
[root@homepc ~]# uname -a
Linux homepc.nigelterry.net 2.6.27.7-53.fc9.x86_64 #1 SMP Thu Nov 27
02:05:02 EST 2008 x86_64 x86_64 x86_64 GNU/Linux
[root@homepc ~]#
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