* Stuck reshape
@ 2013-11-22 19:17 Larkin Lowrey
2013-11-24 23:43 ` NeilBrown
0 siblings, 1 reply; 3+ messages in thread
From: Larkin Lowrey @ 2013-11-22 19:17 UTC (permalink / raw)
To: linux-raid
I have a reshape that got stuck on what appears to be step 1 of the process.
What can be done? Will a shutdown be recoverable, or should I be
prepared to restore from backup?
I can read from the array w/o error.
I initiated the re-shape with the following command (devices 4->5, level
5->6, chunk 512->256):
mdadm --grow /dev/md1 --level=6 --raid-devices=6 --chunk=256
The output was:
mdadm: level of /dev/md1 changed to raid6
mdadm: Need to backup 3072K of critical section..
The status is:
md1 : active raid6 sdo1[6] sdn1[5] sdd1[2] sdb1[4] sdc1[0] sda1[1]
2929890816 blocks super 1.2 level 6, 512k chunk, algorithm 18
[6/5] [UUUU_U]
[>....................] reshape = 0.0% (512/976630272)
finish=56199369.9min speed=0K/sec
bitmap: 0/1 pages [0KB], 1048576KB chunk
This process is chewing up a lot of CPU:
2858 root 20 0 7936 3692 280 R 91.5 0.0 35:23.72 mdadm
2856 root 20 0 0 0 0 R 24.4 0.0 14:05.14
md1_raid6
2857 root 20 0 0 0 0 R 12.2 0.0 4:28.68
md1_reshape
(that's 91.5% for mdadm, 24.4% for md1_raid6, and 12.2% for md1_reshape)
All drives are on-line and functioning normally. I did forget to remove
the internal bitmap and I also forgot to use an external backup file.
mdadm - v3.2.6 - 25th October 2012
kernel: 3.11.8-200.fc19.x86_64
Syslog is:
[ 601.373480] md: bind<sdn1>
[ 601.773482] md: bind<sdo1>
[ 601.824051] RAID conf printout:
[ 601.824058] --- level:5 rd:4 wd:4
[ 601.824062] disk 0, o:1, dev:sdc1
[ 601.824065] disk 1, o:1, dev:sda1
[ 601.824068] disk 2, o:1, dev:sdd1
[ 601.824071] disk 3, o:1, dev:sdb1
[ 601.824073] RAID conf printout:
[ 601.824075] --- level:5 rd:4 wd:4
[ 601.824078] disk 0, o:1, dev:sdc1
[ 601.824080] disk 1, o:1, dev:sda1
[ 601.824083] disk 2, o:1, dev:sdd1
[ 601.824085] disk 3, o:1, dev:sdb1
[ 647.692320] md/raid:md1: device sdd1 operational as raid disk 2
[ 647.698547] md/raid:md1: device sdb1 operational as raid disk 3
[ 647.704787] md/raid:md1: device sdc1 operational as raid disk 0
[ 647.710941] md/raid:md1: device sda1 operational as raid disk 1
[ 647.718258] md/raid:md1: allocated 5394kB
[ 647.752152] md/raid:md1: raid level 6 active with 4 out of 5 devices,
algorithm 18
[ 647.760088] RAID conf printout:
[ 647.760092] --- level:6 rd:5 wd:4
[ 647.760096] disk 0, o:1, dev:sdc1
[ 647.760100] disk 1, o:1, dev:sda1
[ 647.760103] disk 2, o:1, dev:sdd1
[ 647.760105] disk 3, o:1, dev:sdb1
[ 648.622041] RAID conf printout:
[ 648.622049] --- level:6 rd:6 wd:5
[ 648.622053] disk 0, o:1, dev:sdc1
[ 648.622057] disk 1, o:1, dev:sda1
[ 648.622059] disk 2, o:1, dev:sdd1
[ 648.622062] disk 3, o:1, dev:sdb1
[ 648.622065] disk 4, o:1, dev:sdo1
[ 648.622072] RAID conf printout:
[ 648.622074] --- level:6 rd:6 wd:5
[ 648.622077] disk 0, o:1, dev:sdc1
[ 648.622079] disk 1, o:1, dev:sda1
[ 648.622082] disk 2, o:1, dev:sdd1
[ 648.622084] disk 3, o:1, dev:sdb1
[ 648.622087] disk 4, o:1, dev:sdo1
[ 648.622089] disk 5, o:1, dev:sdn1
[ 648.622475] md: reshape of RAID array md1
[ 648.626832] md: minimum _guaranteed_ speed: 1000 KB/sec/disk.
[ 648.633041] md: using maximum available idle IO bandwidth (but not
more than 200000 KB/sec) for reshape.
[ 648.643053] md: using 128k window, over a total of 976630272k.
--Larkin
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: Stuck reshape
2013-11-22 19:17 Stuck reshape Larkin Lowrey
@ 2013-11-24 23:43 ` NeilBrown
2013-11-25 1:44 ` Larkin Lowrey
0 siblings, 1 reply; 3+ messages in thread
From: NeilBrown @ 2013-11-24 23:43 UTC (permalink / raw)
To: Larkin Lowrey; +Cc: linux-raid
[-- Attachment #1: Type: text/plain, Size: 4715 bytes --]
On Fri, 22 Nov 2013 13:17:52 -0600 Larkin Lowrey <llowrey@nuclearwinter.com>
wrote:
> I have a reshape that got stuck on what appears to be step 1 of the process.
>
> What can be done? Will a shutdown be recoverable, or should I be
> prepared to restore from backup?
>
> I can read from the array w/o error.
If it is convenient to take a backup, or a copy of the more important files,
that might not be a bad idea. It shouldn't be necessary, but better safe
than sorry.
>
> I initiated the re-shape with the following command (devices 4->5, level
> 5->6, chunk 512->256):
> mdadm --grow /dev/md1 --level=6 --raid-devices=6 --chunk=256
So devices: 4 -> 6 ??
>
> The output was:
> mdadm: level of /dev/md1 changed to raid6
> mdadm: Need to backup 3072K of critical section..
>
> The status is:
>
> md1 : active raid6 sdo1[6] sdn1[5] sdd1[2] sdb1[4] sdc1[0] sda1[1]
> 2929890816 blocks super 1.2 level 6, 512k chunk, algorithm 18
> [6/5] [UUUU_U]
> [>....................] reshape = 0.0% (512/976630272)
> finish=56199369.9min speed=0K/sec
> bitmap: 0/1 pages [0KB], 1048576KB chunk
>
> This process is chewing up a lot of CPU:
> 2858 root 20 0 7936 3692 280 R 91.5 0.0 35:23.72 mdadm
> 2856 root 20 0 0 0 0 R 24.4 0.0 14:05.14
> md1_raid6
> 2857 root 20 0 0 0 0 R 12.2 0.0 4:28.68
> md1_reshape
>
> (that's 91.5% for mdadm, 24.4% for md1_raid6, and 12.2% for md1_reshape)
>
> All drives are on-line and functioning normally. I did forget to remove
> the internal bitmap and I also forgot to use an external backup file.
You don't need a backup file when increasing the number of data drives, and
recent kernels don't need you to remove the bitmap (and one those that did,
it would fail cleanly).
So these aren't problems.
Still, something is clearly wrong.
It should be completely safe to reboot ... but given that I don't know what
the reshape is hanging here I cannot promise that the reshape won't hang
again after a reboot.
I'll try to reproduce this and see if I can understand what is happening.
Meanwhile ... maybe try killing mdadm. That certainly won't hurt and may
help.
NeilBrown
>
> mdadm - v3.2.6 - 25th October 2012
> kernel: 3.11.8-200.fc19.x86_64
>
> Syslog is:
>
> [ 601.373480] md: bind<sdn1>
> [ 601.773482] md: bind<sdo1>
> [ 601.824051] RAID conf printout:
> [ 601.824058] --- level:5 rd:4 wd:4
> [ 601.824062] disk 0, o:1, dev:sdc1
> [ 601.824065] disk 1, o:1, dev:sda1
> [ 601.824068] disk 2, o:1, dev:sdd1
> [ 601.824071] disk 3, o:1, dev:sdb1
> [ 601.824073] RAID conf printout:
> [ 601.824075] --- level:5 rd:4 wd:4
> [ 601.824078] disk 0, o:1, dev:sdc1
> [ 601.824080] disk 1, o:1, dev:sda1
> [ 601.824083] disk 2, o:1, dev:sdd1
> [ 601.824085] disk 3, o:1, dev:sdb1
> [ 647.692320] md/raid:md1: device sdd1 operational as raid disk 2
> [ 647.698547] md/raid:md1: device sdb1 operational as raid disk 3
> [ 647.704787] md/raid:md1: device sdc1 operational as raid disk 0
> [ 647.710941] md/raid:md1: device sda1 operational as raid disk 1
> [ 647.718258] md/raid:md1: allocated 5394kB
> [ 647.752152] md/raid:md1: raid level 6 active with 4 out of 5 devices,
> algorithm 18
> [ 647.760088] RAID conf printout:
> [ 647.760092] --- level:6 rd:5 wd:4
> [ 647.760096] disk 0, o:1, dev:sdc1
> [ 647.760100] disk 1, o:1, dev:sda1
> [ 647.760103] disk 2, o:1, dev:sdd1
> [ 647.760105] disk 3, o:1, dev:sdb1
> [ 648.622041] RAID conf printout:
> [ 648.622049] --- level:6 rd:6 wd:5
> [ 648.622053] disk 0, o:1, dev:sdc1
> [ 648.622057] disk 1, o:1, dev:sda1
> [ 648.622059] disk 2, o:1, dev:sdd1
> [ 648.622062] disk 3, o:1, dev:sdb1
> [ 648.622065] disk 4, o:1, dev:sdo1
> [ 648.622072] RAID conf printout:
> [ 648.622074] --- level:6 rd:6 wd:5
> [ 648.622077] disk 0, o:1, dev:sdc1
> [ 648.622079] disk 1, o:1, dev:sda1
> [ 648.622082] disk 2, o:1, dev:sdd1
> [ 648.622084] disk 3, o:1, dev:sdb1
> [ 648.622087] disk 4, o:1, dev:sdo1
> [ 648.622089] disk 5, o:1, dev:sdn1
> [ 648.622475] md: reshape of RAID array md1
> [ 648.626832] md: minimum _guaranteed_ speed: 1000 KB/sec/disk.
> [ 648.633041] md: using maximum available idle IO bandwidth (but not
> more than 200000 KB/sec) for reshape.
> [ 648.643053] md: using 128k window, over a total of 976630272k.
>
> --Larkin
> --
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> the body of a message to majordomo@vger.kernel.org
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Stuck reshape
2013-11-24 23:43 ` NeilBrown
@ 2013-11-25 1:44 ` Larkin Lowrey
0 siblings, 0 replies; 3+ messages in thread
From: Larkin Lowrey @ 2013-11-25 1:44 UTC (permalink / raw)
To: NeilBrown; +Cc: linux-raid
On 11/24/2013 5:43 PM, NeilBrown wrote:
>> I initiated the re-shape with the following command (devices 4->5, level
>> 5->6, chunk 512->256):
>> mdadm --grow /dev/md1 --level=6 --raid-devices=6 --chunk=256
>
> So devices: 4 -> 6 ??
Correct, devices 4->6.
>
>>
>> The output was:
>> mdadm: level of /dev/md1 changed to raid6
>> mdadm: Need to backup 3072K of critical section..
>>
>> The status is:
>>
>> md1 : active raid6 sdo1[6] sdn1[5] sdd1[2] sdb1[4] sdc1[0] sda1[1]
>> 2929890816 blocks super 1.2 level 6, 512k chunk, algorithm 18
>> [6/5] [UUUU_U]
>> [>....................] reshape = 0.0% (512/976630272)
>> finish=56199369.9min speed=0K/sec
>> bitmap: 0/1 pages [0KB], 1048576KB chunk
>>
>> This process is chewing up a lot of CPU:
>> 2858 root 20 0 7936 3692 280 R 91.5 0.0 35:23.72 mdadm
>> 2856 root 20 0 0 0 0 R 24.4 0.0 14:05.14
>> md1_raid6
>> 2857 root 20 0 0 0 0 R 12.2 0.0 4:28.68
>> md1_reshape
>>
>> (that's 91.5% for mdadm, 24.4% for md1_raid6, and 12.2% for md1_reshape)
>>
>> All drives are on-line and functioning normally. I did forget to remove
>> the internal bitmap and I also forgot to use an external backup file.
>
> You don't need a backup file when increasing the number of data
drives, and
> recent kernels don't need you to remove the bitmap (and one those that
did,
> it would fail cleanly).
> So these aren't problems.
>
> Still, something is clearly wrong.
>
> It should be completely safe to reboot ... but given that I don't know
what
> the reshape is hanging here I cannot promise that the reshape won't hang
> again after a reboot.
>
> I'll try to reproduce this and see if I can understand what is happening.
> Meanwhile ... maybe try killing mdadm. That certainly won't hurt and may
> help.
>
> NeilBrown
>
Thank you for your reply. I managed to resolve this issue but hadn't
gotten around to replying with an update.
I noticed, via strace, that mdadm was reading from sysfs as fast as it
could and was trying to open sync_completed O_RDWR which it was unable
to do since it was read-only. Just for fun I changed sync_completed to
0644 and all mdadm did with that file was read from it. This was with
mdadm v3.2.6. This 'fix' did not change any aspect of the behavior other
than allowing mdadm to read the file w/o error.
I finally decided to 'echo max > /sys/block/md1/md/sync_max'. It had
been stuck at 1024. That unstuck the reshape and it completed
successfully. Being paranoid, I did a full compare of the most recent
backup and no (unexpected) differences were detected.
I did a 'echo t > /proc/sysrq-trigger' while things were stuck but it
overran the buffer rather badly.
--Larkin
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