I had a RAID5 array set up as /dev/md1 using 4 external USB3 drives.
Following a reboot (I assume, although to be honest I'm not sure what caused it) the array hasn't come back up correctly: $ cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md1 : active raid5 super 1.2 level 5, 512k chunk, algorithm 2 [4/0] [____]
md0 : active raid5 sda1[0] sdb1[1] sdd1[3] sdc1[2] 5860535808 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU]
unused devices: <none>
Note: /dev/md0 is a separate array and is working fine; md1 should comprise sd[fghi]1
All the "missing" partitions are present, eg: $sudo fdisk -l /dev/sdf
Disk /dev/sdf: 2000.4 GB, 2000398934016 bytes 81 heads, 63 sectors/track, 765633 cylinders, total 3907029168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x2c2d5341
Device Boot Start End Blocks Id System /dev/sdf1 2048 3907029167 1953513560 fd Linux RAID autodetect
(same applies for the other three disks).
How do I get mdadm to add my disks into the array, both now and after a reboot?