From: NeilBrown <neilb@suse.de>
To: Rory Jaffe <rsjaffe@gmail.com>
Cc: Phil Turmel <philip@turmel.org>,
Mikael Abrahamsson <swmike@swm.pp.se>,
linux-raid@vger.kernel.org
Subject: Re: RAID5 Shrinking array-size nearly killed the system
Date: Tue, 15 Mar 2011 16:44:41 +1100 [thread overview]
Message-ID: <20110315164441.109af85e@notabene.brown> (raw)
In-Reply-To: <AANLkTinHVJh-fd2z6Rq037CuAUXwnJK1tEjgxM60OHnP@mail.gmail.com>
On Tue, 15 Mar 2011 05:26:44 +0000 Rory Jaffe <rsjaffe@gmail.com> wrote:
> >> One more glitch? I ran the following command, trying several different
> >> locations for the backup file, all of which have plenty of space and
> >> are not on the array.
> >>
> >> sudo mdadm -G /dev/md/0_0 -n 4 --backup-file=/tmp/backmd
> >>
> >> mdadm gives the message "mdadm: Need to backup 960K of critical
> >> section.." and it immediately returns to the command prompt without
> >> shrinking the array.
> >
> > Are you sure its not doing the reshape? "cat /proc/mdstat" will show whats happening in the background.
> >
> > Also, check your dmesg to see if there are any explanatory messages.
> >
> > Phil
> >
> I tried again, with the same results. Details follow:
>
> To assemble the array, I used
> ubuntu@ubuntu:~/mdadm-3.2$ sudo mdadm --assemble --scan
> then
> I resynced the array.
> then
> ubuntu@ubuntu:~/mdadm-3.2$ sudo mdadm --grow /dev/md127 --array-size 5857612608
> then
> ubuntu@ubuntu:~/mdadm-3.2$ sudo mdadm -G -n 4 --backup-file=mdbak /dev/md127
> and again received the messages:
> ubuntu@ubuntu:~/mdadm-3.2$ sudo mdadm -G -n 4 --backup-file=mdback /dev/md127
> mdadm: Need to backup 960K of critical section..
> ubuntu@ubuntu:~/mdadm-3.2$ cat /proc/mdstat
> Personalities : [raid6] [raid5] [raid4]
> md127 : active raid5 sda2[0] sdh2[5] sdg2[4] sdf2[3] sde2[2] sdd2[1]
> 5857612608 blocks level 5, 64k chunk, algorithm 2 [6/6] [UUUUUU]
>
> unused devices: <none>
> ubuntu@ubuntu:~/mdadm-3.2$ mdadm -V
> mdadm - v3.2 DEVELOPER_ONLY - 1st February 2011 (USE WITH CARE)
^^^^^^^^^^^^^^ ^^^^^^^^^^^^^
I guess you must be a developer, so probably don't need any help....
But may I suggest trying mdadm-3.1.4 instead??
NeilBrown
>
>
> The following appear to be the relevant parts of dmesg--
>
> [ 758.516860] md: md127 stopped.
> [ 758.522499] md: bind<sdd2>
> [ 758.523731] md: bind<sde2>
> [ 758.525170] md: bind<sdf2>
> [ 758.525588] md: bind<sdg2>
> [ 758.526003] md: bind<sdh2>
> [ 758.526748] md: bind<sda2>
> [ 758.567380] async_tx: api initialized (async)
> [ 758.740173] raid6: int64x1 335 MB/s
> [ 758.910051] raid6: int64x2 559 MB/s
> [ 759.080062] raid6: int64x4 593 MB/s
> [ 759.250058] raid6: int64x8 717 MB/s
> [ 759.420148] raid6: sse2x1 437 MB/s
> [ 759.590013] raid6: sse2x2 599 MB/s
> [ 759.760037] raid6: sse2x4 634 MB/s
> [ 759.760044] raid6: using algorithm sse2x4 (634 MB/s)
> [ 759.793413] md: raid6 personality registered for level 6
> [ 759.793423] md: raid5 personality registered for level 5
> [ 759.793429] md: raid4 personality registered for level 4
> [ 759.798708] md/raid:md127: device sda2 operational as raid disk 0
> [ 759.798720] md/raid:md127: device sdh2 operational as raid disk 5
> [ 759.798729] md/raid:md127: device sdg2 operational as raid disk 4
> [ 759.798739] md/raid:md127: device sdf2 operational as raid disk 3
> [ 759.798747] md/raid:md127: device sde2 operational as raid disk 2
> [ 759.798756] md/raid:md127: device sdd2 operational as raid disk 1
> [ 759.800722] md/raid:md127: allocated 6386kB
> [ 759.810239] md/raid:md127: raid level 5 active with 6 out of 6
> devices, algorithm 2
> [ 759.810249] RAID conf printout:
> [ 759.810255] --- level:5 rd:6 wd:6
> [ 759.810263] disk 0, o:1, dev:sda2
> [ 759.810271] disk 1, o:1, dev:sdd2
> [ 759.810278] disk 2, o:1, dev:sde2
> [ 759.810285] disk 3, o:1, dev:sdf2
> [ 759.810293] disk 4, o:1, dev:sdg2
> [ 759.810300] disk 5, o:1, dev:sdh2
> [ 759.810416] md127: detected capacity change from 0 to 9996992184320
> [ 759.825149] md127: unknown partition table
> [ 810.381494] md127: detected capacity change from 9996992184320 to
> 5998195310592
> [ 810.384868] md127: unknown partition table
>
> and here is the information about the array.
> sudo mdadm -D /dev/md127
> /dev/md127:
> Version : 0.90
> Creation Time : Thu Jan 6 06:13:08 2011
> Raid Level : raid5
> Array Size : 5857612608 (5586.25 GiB 5998.20 GB)
> Used Dev Size : 1952537536 (1862.08 GiB 1999.40 GB)
> Raid Devices : 6
> Total Devices : 6
> Preferred Minor : 127
> Persistence : Superblock is persistent
>
> Update Time : Tue Mar 15 00:45:28 2011
> State : clean
> Active Devices : 6
> Working Devices : 6
> Failed Devices : 0
> Spare Devices : 0
>
> Layout : left-symmetric
> Chunk Size : 64K
>
> UUID : 7e946e9d:b6a3395c:b57e8a13:68af0467
> Events : 0.76
>
> Number Major Minor RaidDevice State
> 0 8 2 0 active sync /dev/sda2
> 1 8 50 1 active sync /dev/sdd2
> 2 8 66 2 active sync /dev/sde2
> 3 8 82 3 active sync /dev/sdf2
> 4 8 98 4 active sync /dev/sdg2
> 5 8 114 5 active sync /dev/sdh2
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next prev parent reply other threads:[~2011-03-15 5:44 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <AANLkTimrq904HRZfx6RpPrVNd0EJ5AkUZtytY7TqcFYv@mail.gmail.com>
2011-03-12 4:58 ` RAID5 Shrinking array-size nearly killed the system Rory Jaffe
2011-03-12 5:56 ` Mikael Abrahamsson
2011-03-12 14:40 ` Phil Turmel
[not found] ` <AANLkTik2qk2ep7fsQPjAesnjur-0AB-Xx7EeZ5YfeCSA@mail.gmail.com>
2011-03-12 17:47 ` [PATCH] Add more warnings to --grow documentation (was: RAID5 Shrinking array-size nearly killed the system) Phil Turmel
[not found] ` <AANLkTikRdqZ4nAdLcUuYz17KeWb54ES_sNYzzW-u1R0x@mail.gmail.com>
2011-03-12 17:58 ` RAID5 Shrinking array-size nearly killed the system Phil Turmel
2011-03-12 18:31 ` Rory Jaffe
[not found] ` <AANLkTim+OwO5-w5Hhjdchp+Nj8k0zTLqqvRKfAzFgkWz@mail.gmail.com>
2011-03-12 20:10 ` Phil Turmel
2011-03-13 6:56 ` Rory Jaffe
2011-03-13 13:33 ` Phil Turmel
2011-03-15 5:26 ` Rory Jaffe
2011-03-15 5:44 ` NeilBrown [this message]
2011-03-15 5:53 ` Rory Jaffe
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