nas brot # mdadm -D /dev/md0 /dev/md0: Version : 1.0 Creation Time : Fri Aug 24 04:18:31 2012 Raid Level : raid1 Array Size : 511988 (500.07 MiB 524.28 MB) Used Dev Size : 511988 (500.07 MiB 524.28 MB) Raid Devices : 2 Total Devices : 3 Persistence : Superblock is persistent Update Time : Sun Nov 16 19:15:17 2014 State : clean Active Devices : 2 Working Devices : 3 Failed Devices : 0 Spare Devices : 1 Name : localhost.localdomain:0 UUID : 262c8e68:c7c4fa6d:19af27e8:0cfc68a1 Events : 248 Number Major Minor RaidDevice State 0 8 2 0 active sync /dev/sda2 4 8 33 1 active sync /dev/sdc1 3 8 17 - spare /dev/sdb1 nas brot # mdadm --verbose --manage --add /dev/md0 /dev/sdd2 mdadm: added /dev/sdd2 nas brot # mdadm --verbose --manage --add /dev/md0 /dev/sde2 mdadm: added /dev/sde2 nas brot # cat /proc/mdstat Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] md2 : active raid5 sdb3[6] sdc3[5] sda3[0] 52430848 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU] md4 : active raid5 sdb4[2] sdc4[1] sda4[3] 5753362432 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU] bitmap: 0/22 pages [0KB], 65536KB chunk md0 : active raid1 sde2[5](S) sdd2[2](S) sdb1[3](S) sdc1[4] sda2[0] 511988 blocks super 1.0 [2/2] [UU] unused devices: nas brot # mdadm /dev/md0 --fail /dev/sdc1 mdadm: set /dev/sdc1 faulty in /dev/md0 nas brot # mdadm /dev/md0 --fail /dev/sdb1 mdadm: set /dev/sdb1 faulty in /dev/md0 nas brot # cat /proc/mdstat Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] md2 : active raid5 sdb3[6] sdc3[5] sda3[0] 52430848 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU] md4 : active raid5 sdb4[2] sdc4[1] sda4[3] 5753362432 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU] bitmap: 0/22 pages [0KB], 65536KB chunk md0 : active raid1 sde2[5] sdd2[2](S) sdb1[3](S) sdc1[4](F) sda2[0] 511988 blocks super 1.0 [2/1] [U_] [==========>..........] recovery = 52.9% (270912/511988) finish=0.0min speed=67728K/sec nas brot # mdadm /dev/md0 --remove /dev/sdb1 /dev/sdc1 mdadm: hot removed /dev/sdb1 from /dev/md0 mdadm: hot removed /dev/sdc1 from /dev/md0 nas brot # mdadm -D /dev/md0 /dev/md0: Version : 1.0 Creation Time : Fri Aug 24 04:18:31 2012 Raid Level : raid1 Array Size : 511988 (500.07 MiB 524.28 MB) Used Dev Size : 511988 (500.07 MiB 524.28 MB) Raid Devices : 2 Total Devices : 3 Persistence : Superblock is persistent Update Time : Sun Nov 16 19:41:39 2014 State : clean Active Devices : 2 Working Devices : 3 Failed Devices : 0 Spare Devices : 1 Name : localhost.localdomain:0 UUID : 262c8e68:c7c4fa6d:19af27e8:0cfc68a1 Events : 277 Number Major Minor RaidDevice State 0 8 2 0 active sync /dev/sda2 5 8 66 1 active sync /dev/sde2 2 8 50 - spare /dev/sdd2 nas brot # mdadm --grow /dev/md0 --raid-devices=3 raid_disks for /dev/md0 set to 3 unfreeze nas brot # mdadm -D /dev/md0 /dev/md0: Version : 1.0 Creation Time : Fri Aug 24 04:18:31 2012 Raid Level : raid1 Array Size : 511988 (500.07 MiB 524.28 MB) Used Dev Size : 511988 (500.07 MiB 524.28 MB) Raid Devices : 3 Total Devices : 3 Persistence : Superblock is persistent Update Time : Sun Nov 16 19:45:49 2014 State : clean, degraded, recovering Active Devices : 2 Working Devices : 3 Failed Devices : 0 Spare Devices : 1 Rebuild Status : 81% complete Name : localhost.localdomain:0 UUID : 262c8e68:c7c4fa6d:19af27e8:0cfc68a1 Events : 296 Number Major Minor RaidDevice State 0 8 2 0 active sync /dev/sda2 5 8 66 1 active sync /dev/sde2 2 8 50 2 spare rebuilding /dev/sdd2