Re: Adding a disk to RAID0

[NeilBrown <neilb@suse.de>]

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On Mon, 05 Mar 2012 15:35:15 -0800 Victor Balakine <victor.balakine@ubc.ca>
wrote:

> Am I the only one having problem adding disks to RAID0? Has anybody 
> tried that on 3.* kernel?

Strange.  It works for me.

We need to find out what the md0_raid0 process is doing.
Can you
   cat /proc/PROCESSID/stack

and see what that shows?

NeilBrown


> 
> Victor
> 
> On 2012-02-28 15:34, Victor Balakine wrote:
> > I am trying to add another disk to RAID0 and this functionality appears
> > to be broken.
> > First I create a RAID0 array:
> > #mdadm --create /dev/md0 --level=0 --raid-devices=1 --force /dev/xvda2
> > mdadm: Defaulting to version 1.2 metadata
> > mdadm: array /dev/md0 started.
> >
> > So far everything works fine. Then I add another disk to it:
> > #mdadm --grow /dev/md0 --raid-devices=2 --add /dev/xvda3
> > --backup-file=/backup-md0
> > mdadm: level of /dev/md0 changed to raid4
> > mdadm: added /dev/xvda3
> > mdadm: Need to backup 1024K of critical section..
> >
> > This is what I see in /var/log/messages
> > Feb 28 15:03:30 storage kernel: [ 1420.174022] md: bind<xvda2>
> > Feb 28 15:03:30 storage kernel: [ 1420.209167] md: raid0 personality
> > registered for level 0
> > Feb 28 15:03:30 storage kernel: [ 1420.209818] bio: create slab <bio-1>
> > at 1
> > Feb 28 15:03:30 storage kernel: [ 1420.209832] md/raid0:md0: looking at
> > xvda2
> > Feb 28 15:03:30 storage kernel: [ 1420.209837] md/raid0:md0: comparing
> > xvda2(8386560) with xvda2(8386560)
> > Feb 28 15:03:30 storage kernel: [ 1420.209844] md/raid0:md0: END
> > Feb 28 15:03:30 storage kernel: [ 1420.209851] md/raid0:md0: ==> UNIQUE
> > Feb 28 15:03:30 storage kernel: [ 1420.209856] md/raid0:md0: 1 zones
> > Feb 28 15:03:30 storage kernel: [ 1420.209859] md/raid0:md0: FINAL 1 zones
> > Feb 28 15:03:30 storage kernel: [ 1420.209866] md/raid0:md0: done.
> > Feb 28 15:03:30 storage kernel: [ 1420.209870] md/raid0:md0: md_size is
> > 8386560 sectors.
> > Feb 28 15:03:30 storage kernel: [ 1420.209875] ******* md0 configuration
> > *********
> > Feb 28 15:03:30 storage kernel: [ 1420.209879] zone0=[xvda2/]
> > Feb 28 15:03:30 storage kernel: [ 1420.209885] zone offset=0kb device
> > offset=0kb size=4193280kb
> > Feb 28 15:03:30 storage kernel: [ 1420.209902]
> > **********************************
> > Feb 28 15:03:30 storage kernel: [ 1420.209903]
> > Feb 28 15:03:30 storage kernel: [ 1420.209919] md0: detected capacity
> > change from 0 to 4293918720
> > Feb 28 15:03:30 storage kernel: [ 1420.223968] md0: p1
> > ...
> > Feb 28 15:04:01 storage kernel: [ 1450.783016] async_tx: api initialized
> > (async)
> > Feb 28 15:04:01 storage kernel: [ 1450.796912] xor: automatically using
> > best checksumming function: generic_sse
> > Feb 28 15:04:01 storage kernel: [ 1450.816012] generic_sse: 9509.000 MB/sec
> > Feb 28 15:04:01 storage kernel: [ 1450.816021] xor: using function:
> > generic_sse (9509.000 MB/sec)
> > Feb 28 15:04:01 storage kernel: [ 1450.912021] raid6: int64x1 1888 MB/s
> > Feb 28 15:04:01 storage kernel: [ 1450.980013] raid6: int64x2 2707 MB/s
> > Feb 28 15:04:01 storage kernel: [ 1451.048025] raid6: int64x4 2073 MB/s
> > Feb 28 15:04:01 storage kernel: [ 1451.116039] raid6: int64x8 2010 MB/s
> > Feb 28 15:04:01 storage kernel: [ 1451.184017] raid6: sse2x1 4764 MB/s
> > Feb 28 15:04:01 storage kernel: [ 1451.252018] raid6: sse2x2 5170 MB/s
> > Feb 28 15:04:01 storage kernel: [ 1451.320016] raid6: sse2x4 7548 MB/s
> > Feb 28 15:04:01 storage kernel: [ 1451.320025] raid6: using algorithm
> > sse2x4 (7548 MB/s)
> > Feb 28 15:04:01 storage kernel: [ 1451.330136] md: raid6 personality
> > registered for level 6
> > Feb 28 15:04:01 storage kernel: [ 1451.330145] md: raid5 personality
> > registered for level 5
> > Feb 28 15:04:01 storage kernel: [ 1451.330149] md: raid4 personality
> > registered for level 4
> > Feb 28 15:04:01 storage kernel: [ 1451.330662] md/raid:md0: device xvda2
> > operational as raid disk 0
> > Feb 28 15:04:01 storage kernel: [ 1451.330820] md/raid:md0: allocated
> > 2176kB
> > Feb 28 15:04:01 storage kernel: [ 1451.330869] md/raid:md0: raid level 4
> > active with 1 out of 2 devices, algorithm 5
> > Feb 28 15:04:01 storage kernel: [ 1451.330874] RAID conf printout:
> > Feb 28 15:04:01 storage kernel: [ 1451.330876] --- level:4 rd:2 wd:1
> > Feb 28 15:04:01 storage kernel: [ 1451.330878] disk 0, o:1, dev:xvda2
> > Feb 28 15:04:01 storage kernel: [ 1451.417995] md: bind<xvda3>
> > Feb 28 15:04:01 storage kernel: [ 1451.616399] RAID conf printout:
> > Feb 28 15:04:01 storage kernel: [ 1451.616404] --- level:4 rd:3 wd:2
> > Feb 28 15:04:01 storage kernel: [ 1451.616408] disk 0, o:1, dev:xvda2
> > Feb 28 15:04:01 storage kernel: [ 1451.616411] disk 1, o:1, dev:xvda3
> > Feb 28 15:04:01 storage kernel: [ 1451.619054] md: reshape of RAID array
> > md0
> > Feb 28 15:04:01 storage kernel: [ 1451.619066] md: minimum _guaranteed_
> > speed: 1000 KB/sec/disk.
> > Feb 28 15:04:01 storage kernel: [ 1451.619069] md: using maximum
> > available idle IO bandwidth (but not more than 200000 KB/sec) for reshape.
> > Feb 28 15:04:01 storage kernel: [ 1451.619075] md: using 128k window,
> > over a total of 4193280k.
> > Feb 28 15:05:02 storage udevd[280]: timeout '/sbin/blkid -o udev -p
> > /dev/md0'
> > Feb 28 15:05:03 storage udevd[280]: timeout: killing '/sbin/blkid -o
> > udev -p /dev/md0' [1829]
> > Feb 28 15:05:04 storage udevd[280]: timeout: killing '/sbin/blkid -o
> > udev -p /dev/md0' [1829]
> > Feb 28 15:05:05 storage udevd[280]: timeout: killing '/sbin/blkid -o
> > udev -p /dev/md0' [1829]
> >
> > And then it just goes on forever. md0_raid0 process stays at 100% CPU load.
> > # ps -ef | grep md0
> > root 7268 2 99 09:34 ? 05:53:00 [md0_raid0]
> > root 7270 2 0 09:34 ? 00:00:00 [md0_reshape]
> > root 7271 1 0 09:34 pts/0 00:00:00 mdadm --grow /dev/md0
> > --raid-devices=2 --add /dev/sdc1 --backup-file=/backup-md0
> >
> > # cat /proc/mdstat
> > Personalities : [raid0] [raid6] [raid5] [raid4]
> > md0 : active raid4 xvda3[2] xvda2[0]
> > 4193280 blocks super 1.2 level 4, 512k chunk, algorithm 5 [3/1] [U__]
> > resync=DELAYED
> >
> > unused devices: <none>
> >
> > # mdadm --version
> > mdadm - v3.2.2 - 17th June 2011
> > # uname -a
> > Linux storage 3.1.9-1.4-xen #1 SMP Fri Jan 27 08:55:10 UTC 2012
> > (efb5ff4) x86_64 x86_64 x86_64 GNU/Linux
> >
> > It's OpenSUSE 12.1 with all the latest updates running in XEN that I
> > created to reproduce the problem. The actual server is running the same
> > version of OpenSUSE (Linux san1 3.1.9-1.4-desktop #1 SMP PREEMPT Fri Jan
> > 27 08:55:10 UTC 2012 (efb5ff4) x86_64 x86_64 x86_64 GNU/Linux) on a
> > hardware server. If you need any more information I can easily get it
> > since it's a VM and the problem is easily reproducible.
> >
> > Victor
> > --
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