mdadm doc

Due to the replacement by mdadm over raidtools, /dev/md0 failed to work well with mdadm. It seems /dev/md0 is called a legacy array without a superblock in mdadm. Anyway, /dev/md0 is raid1 with /dev/sdb1 and /dev/sdc1 mirroring.

Useful mdadm commands:

Assemble

mdadm -As /dev/md0 (with /etc/mdadm.conf to scan)or mdadm -A /dev/md0 /dev/sdb1 /dev/sdc1

Query

mdadm -Q -D /dev/md0 (-D gives more detailed)

Examine

mdadm -E /dev/md0

Solution I:

• stop the array and release sdb1 and sdc1 mdadm -S /dev/md0 and mount either of them to /db.

Solution II:

• bind the 1st drive mdadm -A /dev/md0 /dev/sdc1 (it seems /dev/sdb1 is not the 1st drive. Same command with /dev/sdb1 failed)
• optional. start md0 mdadm -R /dev/md0 (this is necessary only if mdadm -S /dev/md0 has been executed)
• add another drive, mdadm /dev/md0 -a /dev/sdb1 (this will resynch md0)
• check resynching status, cat /proc/mdstat

Solution III(2006-09-08):

• directly assemble the whole md0 mdadm -A /dev/md0 /dev/sdc1 /dev/sdb1. and it's done.
• probably the new sbc(good) makes it possible.

2006-08-24

• sdb1 is the mounted one. sbc1 is old(bad one).
• log from log_05

2006-09-08

Luigi changed the bad one(sbc) and back to /dev/md0.