Status of RAID (md)
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From: Daniel Bareiro on 1 Aug 2010 22:30 Hi all! On the day I found this e-mail notification of fail event from mdadm: --------------------------------------------------------------------- This is an automatically generated mail message from mdadm running on antares A Fail event had been detected on md device /dev/md2. It could be related to component device /dev/sdd3. Faithfully yours, etc. P.S. The /proc/mdstat file currently contains the following: Personalities : [raid1] [raid6] [raid5] [raid4] md2 : active raid5 sda3[0] sdd3[4](F) sdc3[2] 2136170880 blocks level 5, 64k chunk, algorithm 2 [4/2] [U_U_] md1 : active raid1 sda2[0] sdd2[3] sdc2[2] 19534976 blocks [4/3] [U_UU] md0 : active raid1 sda1[0] sdd1[3] sdc1[2] sdb1[1] 979840 blocks [4/4] [UUUU] unused devices: <none> --------------------------------------------------------------------- It seems that a disk of the RAID-5 disappeared and another one has failed. A closer inspection shows: antares:~# mdadm --detail /dev/md2 /dev/md2: Version : 00.90 Creation Time : Thu Dec 17 13:18:29 2009 Raid Level : raid5 Array Size : 2136170880 (2037.21 GiB 2187.44 GB) Used Dev Size : 712056960 (679.07 GiB 729.15 GB) Raid Devices : 4 Total Devices : 3 Preferred Minor : 2 Persistence : Superblock is persistent Update Time : Sun Aug 1 16:38:59 2010 State : clean, degraded Active Devices : 2 Working Devices : 2 Failed Devices : 1 Spare Devices : 0 Layout : left-symmetric Chunk Size : 64K UUID : be723ed5:c2ac3c34:a640c0ed:43e24fc2 Events : 0.726249 Number Major Minor RaidDevice State 0 8 3 0 active sync /dev/sda3 1 0 0 1 removed 2 8 35 2 active sync /dev/sdc3 3 0 0 3 removed 4 8 51 - faulty spare /dev/sdd3 That is to say, the RAID has four disks and failed both the spare disk and other disk from array. What is unclear to me is why if there are two active disks, it seems that the RAID is broken because the filesystem is on read-only mode: # pvs PV VG Fmt Attr PSize PFree /dev/md2 backup lvm2 a- 1,99T 0 # lvs LV VG Attr LSize Origin Snap% Move Log Copy% Convert space backup -wi-ao 1,99T # mount /dev/md1 on / type ext3 (rw,errors=remount-ro) tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /sys type sysfs (rw,noexec,nosuid,nodev) procbususb on /proc/bus/usb type usbfs (rw) udev on /dev type tmpfs (rw,mode=0755) tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev) devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620) /dev/mapper/backup-space on /space type ext3 (ro) Then, I tried to add the missing disk, but the situation did not change: # mdadm --add /dev/md2 /dev/sdb3 mdadm: re-added /dev/sdb3 antares:~# mdadm --detail /dev/md2 /dev/md2: Version : 00.90 Creation Time : Thu Dec 17 13:18:29 2009 Raid Level : raid5 Array Size : 2136170880 (2037.21 GiB 2187.44 GB) Used Dev Size : 712056960 (679.07 GiB 729.15 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 2 Persistence : Superblock is persistent Update Time : Sun Aug 1 17:03:19 2010 State : clean, degraded Active Devices : 2 Working Devices : 3 Failed Devices : 1 Spare Devices : 1 Layout : left-symmetric Chunk Size : 64K UUID : be723ed5:c2ac3c34:a640c0ed:43e24fc2 Events : 0.726256 Number Major Minor RaidDevice State 0 8 3 0 active sync /dev/sda3 1 0 0 1 removed 2 8 35 2 active sync /dev/sdc3 3 0 0 3 removed 4 8 19 - spare /dev/sdb3 5 8 51 - faulty spare /dev/sdd3 # cat /proc/mdstat Personalities : [raid1] [raid6] [raid5] [raid4] md2 : active raid5 sdb3[4](S) sda3[0] sdd3[5](F) sdc3[2] 2136170880 blocks level 5, 64k chunk, algorithm 2 [4/2] [U_U_] md1 : active raid1 sda2[0] sdd2[3] sdc2[2] 19534976 blocks [4/3] [U_UU] md0 : active raid1 sda1[0] sdd1[3] sdc1[2] sdb1[1] 979840 blocks [4/4] [UUUU] unused devices: <none> # mount /dev/md1 on / type ext3 (rw,errors=remount-ro) tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /sys type sysfs (rw,noexec,nosuid,nodev) procbususb on /proc/bus/usb type usbfs (rw) udev on /dev type tmpfs (rw,mode=0755) tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev) devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620) /dev/mapper/backup-space on /space type ext3 (ro) What could be the problem? Thanks in advance for your reply. Regards, Daniel -- Fingerprint: BFB3 08D6 B4D1 31B2 72B9 29CE 6696 BF1B 14E6 1D37 Powered by Debian GNU/Linux Lenny - Linux user #188.598
From: Daniel Bareiro on 2 Aug 2010 09:20 Hi, Martin. On Monday, 02 August 2010 08:30:03 +0200, martin f krafft wrote: > also sprach Daniel Bareiro <daniel-listas(a)gmx.net> [2010.08.02.0420 +0200]: > > md2 : active raid5 sda3[0] sdd3[4](F) sdc3[2] > > 2136170880 blocks level 5, 64k chunk, algorithm 2 [4/2] [U_U_] > [â¦] > > That is to say, the RAID has four disks and failed both the spare > > disk and other disk from array. What is unclear to me is why if > > there are two active disks, > There is no spare disk. The reason why sdd is listed as "faulty > spare" is because it's out of sync. Remove and re-add it: > > mdadm --remove /dev/md2 /dev/sdd3 > mdadm --add /dev/md2 /dev/sdd3 # mdadm --remove /dev/md2 /dev/sdd3 mdadm: hot removed /dev/sdd3 # cat /proc/mdstat Personalities : [raid1] [raid6] [raid5] [raid4] md2 : active raid5 sdb3[4](S) sda3[0] sdc3[2] 2136170880 blocks level 5, 64k chunk, algorithm 2 [4/2] [U_U_] md1 : active raid1 sda2[0] sdd2[3] sdc2[2] 19534976 blocks [4/3] [U_UU] md0 : active raid1 sda1[0] sdd1[3] sdc1[2] sdb1[1] 979840 blocks [4/4] [UUUU] unused devices: <none> # mdadm --add /dev/md2 /dev/sdd3 mdadm: re-added /dev/sdd3 # cat /proc/mdstat Personalities : [raid1] [raid6] [raid5] [raid4] md2 : active raid5 sdd3[4](S) sdb3[5](S) sda3[0] sdc3[2] 2136170880 blocks level 5, 64k chunk, algorithm 2 [4/2] [U_U_] md1 : active raid1 sda2[0] sdd2[3] sdc2[2] 19534976 blocks [4/3] [U_UU] md0 : active raid1 sda1[0] sdd1[3] sdc1[2] sdb1[1] 979840 blocks [4/4] [UUUU] unused devices: <none> It draws attention to me that now both sdb3 and sdd3 are noticeable like spare disks. > > md2 : active raid5 sdb3[4](S) sda3[0] sdd3[5](F) sdc3[2] > > 2136170880 blocks level 5, 64k chunk, algorithm 2 [4/2] [U_U_] > This is indeed a bit strange, but the array might start syncing in > the new disk (called a spare) as soon as you remove sdd3 (see > above). When I tried to add sdb3 was because the disk for some reason did not appear with "cat /proc/mdstat" (not even like it was failed), although when using "mdadm --detail /dev/md2" appear as both sdd3 and sdb3 as removed. To what it can be due that sdb3 does not appear when doing "cat /proc/mdstat"? It is somewhat confusing to see a disk labeled like spare when it is not. Is this "normal"? If this is the case, the only thing I can think of is that after the first disk failure, the system was in interim recovery mode, and during it, the second disk would have failed. Thanks for your reply. Regards, Daniel -- Fingerprint: BFB3 08D6 B4D1 31B2 72B9 29CE 6696 BF1B 14E6 1D37 Powered by Debian GNU/Linux Lenny - Linux user #188.598
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