Hi,
I am testing failures in an md RAID5 scenario, and I am stuck.
Situation: 3 SATA disks with 1 partition, sda1, sdb1 and sdc1 are used to create a RAID5 array.
Now I restart the system with the 'middle' disk powered down. md starts the RAID in degraded mode and works fine, but the system now renamed the partition previously known as sdc1 to sdb1.
I restart, with power to the 'middle' drive restored. The 'middle' drive re-asumes its original name sdb1, and the other disk moves back to sdc1.
Now when md starts it accepts sda1, kicks off sdb1 as outdated, and never seems to even look at sdc1. Hence it will not start the array.
Looking at the superblocks with lsraid sda1 and sdb1 show a state of 'good', sdc1's state is unknown. However the 'last updated' dates on sda1 and sdc1 match, so at least in theory the RAID should be able to start up with those 2 partitions. (see below for superblock listing, it uses aliased device names which did not help though).
Am I correct to assume that md stored the fact that it ran in degraded mode using sda1 and sdb1 (whiich really was sdc1), and hence it never looks at sdc1 again (other than to apparently set the state to 'unknown')?
I attempted to work around the renaming issues using scsidev and 'fixed' device names, but apparently somehow md discovers the original names and works with those at some levels.
Any suggestions? And is there a way to mark the superblock of the 3rd drive as 'good' so that md considers it and will start up?
BTW: Linux xanadu2 2.6.8-1-386 #1 Mon Sep 13 23:29:55 EDT 2004 i686 GNU/Linux
Thanks much
Gerd
xanadu2:~# lsraid -D -d /dev/scsi/cd_1_3-p1 -d /dev/scsi/cd_2_3-p1 -d /dev/scsi/cd_3_3-p1 -l
[dev 8, 1] /dev/scsi/cd_1_3-p1:
md version = 0.90.0
superblock uuid = 0F4274E7.6F390D6E.6521DD63.654D0072
md minor number = 0
created = 1097103636 (Wed Oct 6 18:00:36 2004)
last updated = 1097103991 (Wed Oct 6 18:06:31 2004)
raid level = 5
chunk size = 256 KB
apparent disk size = 47872 KB
disks in array = 2
required disks = 3
active disks = 2
working disks = 2
failed disks = 1
spare disks = 0
position in disk list = 0
position in md device = 0
state = good
[dev 8, 17] /dev/scsi/cd_2_3-p1:
md version = 0.90.0
superblock uuid = 0F4274E7.6F390D6E.6521DD63.654D0072
md minor number = 0
created = 1097103636 (Wed Oct 6 18:00:36 2004)
last updated = 1097103744 (Wed Oct 6 18:02:24 2004)
raid level = 5
chunk size = 256 KB
apparent disk size = 47872 KB
disks in array = 3
required disks = 3
active disks = 3
working disks = 3
failed disks = 0
spare disks = 0
position in disk list = 2
position in md device = 2
state = good[dev 8, 33] /dev/scsi/cd_3_3-p1:
md version = 0.90.0
superblock uuid = 0F4274E7.6F390D6E.6521DD63.654D0072
md minor number = 0
created = 1097103636 (Wed Oct 6 18:00:36 2004)
last updated = 1097103991 (Wed Oct 6 18:06:31 2004)
raid level = 5
chunk size = 256 KB
apparent disk size = 47872 KB
disks in array = 2
required disks = 3
active disks = 2
working disks = 2
failed disks = 1
spare disks = 0
position in disk list = 2
position in md device = 2
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