From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: RAID5 Shrinking array-size nearly killed the system Date: Tue, 15 Mar 2011 16:44:41 +1100 Message-ID: <20110315164441.109af85e@notabene.brown> References: <4D7B85EB.60505@turmel.org> <4D7BB462.5030706@turmel.org> <4D7BD323.3040205@turmel.org> <4D7CC7B9.3010207@turmel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Rory Jaffe Cc: Phil Turmel , Mikael Abrahamsson , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Tue, 15 Mar 2011 05:26:44 +0000 Rory Jaffe wrote= : > >> One more glitch? I ran the following command, trying several diffe= rent > >> locations for the backup file, all of which have plenty of space a= nd > >> are not on the array. > >> > >> sudo mdadm -G /dev/md/0_0 -n 4 --backup-file=3D/tmp/backmd > >> > >> mdadm gives the message "mdadm: Need to backup 960K of critical > >> section.." and it immediately returns to the command prompt withou= t > >> shrinking the array. > > > > Are you sure its not doing the reshape? =A0"cat /proc/mdstat" will = show whats happening in the background. > > > > Also, check your dmesg to see if there are any explanatory messages= =2E > > > > Phil > > > I tried again, with the same results. Details follow: >=20 > 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=3Dmdbak /= dev/md127 > and again received the messages: > ubuntu@ubuntu:~/mdadm-3.2$ sudo mdadm -G -n 4 --backup-file=3Dmdback = /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= ] >=20 > unused devices: > 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 >=20 >=20 > The following appear to be the relevant parts of dmesg-- >=20 > [ 758.516860] md: md127 stopped. > [ 758.522499] md: bind > [ 758.523731] md: bind > [ 758.525170] md: bind > [ 758.525588] md: bind > [ 758.526003] md: bind > [ 758.526748] md: bind > [ 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 999699218432= 0 > [ 759.825149] md127: unknown partition table > [ 810.381494] md127: detected capacity change from 9996992184320 to > 5998195310592 > [ 810.384868] md127: unknown partition table >=20 > 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 >=20 > Update Time : Tue Mar 15 00:45:28 2011 > State : clean > Active Devices : 6 > Working Devices : 6 > Failed Devices : 0 > Spare Devices : 0 >=20 > Layout : left-symmetric > Chunk Size : 64K >=20 > UUID : 7e946e9d:b6a3395c:b57e8a13:68af0467 > Events : 0.76 >=20 > 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 > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid"= in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html