Re: replaced disk in RAID1 imsm array - how to activate?

(oh apologies- I misspelt imsm as imsi in the subject - really mean imsm, the Intel Matrix BIOS fakeraid).

This server has two disks, /dev/sda and /dev/sdb. I created a RAID1 IMSM array in the BIOS, then booted linux and detected the array with

mdadm --examine --scan > /etc/mdadm/mdadm.conf
mdadm --assemble --scan --run --auto=yes

Then /dev/md127 shows up as imsm container, /dev/md126 is the array itself, and (after partitioning) /dev/md looks like this:

root@server3-b05-tpb:~# ls -l /dev/md
total 0
lrwxrwxrwx 1 root root  8 Aug  9 14:15 Volume0 -> ../md126
lrwxrwxrwx 1 root root 10 Aug  9 13:34 Volume0p1 -> ../md126p1
lrwxrwxrwx 1 root root 10 Aug  9 13:34 Volume0p2 -> ../md126p2
lrwxrwxrwx 1 root root 10 Aug  9 13:34 Volume0p5 -> ../md126p5
lrwxrwxrwx 1 root root  8 Aug  9 13:55 imsm0 -> ../md127

Then I removed /dev/sda (by pulling it out), put it back in, zero'd the superblock, added it back with mdadm --add /dev/md127 /dev/sda, and now it just sits there as member of the container, but the array in md126 doesn't start to rebuild.

[ actually, it's a bit more complicated than this, since I am fixing up the debian wheezy installer to support imsm arrays, with quite a bit of success, so I installed debian with this array as the root filesystem ]

Yes, mdmon is running.

dmesg when I pulled out /dev/sda:

ata1: exception Emask 0x50 SAct 0x0 SErr 0x4090800 action 0xe frozen
ata1: irq_stat 0x00400040, connection status changed
ata1: SError: { HostInt PHYRdyChg 10B8B DevExch }
ata1: hard resetting link
ata1: SATA link down (SStatus 0 SControl 300)
ata1: hard resetting link
ata1: SATA link down (SStatus 0 SControl 300)
ata1: limiting SATA link speed to 1.5 Gbps
ata1: hard resetting link
ata1: SATA link down (SStatus 0 SControl 310)
ata1.00: disabled
ata1: EH complete
sd 1:0:0:0: rejecting I/O to offline device
killing request
Unhandled error code
 Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK
CDB: Write(10): 2a 00 57 54 66 ef 00 00 01 00
end_request: I/O error, dev sda, sector 1465149167
ata1.00: detaching (SCSI 1:0:0:0)
Synchronizing SCSI cache
 Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
Stopping disk
START_STOP FAILED
 Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
md/raid1:md126: Disk failure on sda, disabling device.
md/raid1:md126: Operation continuing on 1 devices.
RAID1 conf printout:
 --- wd:1 rd:2
 disk 0, wo:1, o:0, dev:sda
 disk 1, wo:0, o:1, dev:sdb
RAID1 conf printout:
 --- wd:1 rd:2
 disk 1, wo:0, o:1, dev:sdb
md: unbind<sda>
md: export_rdev(sda)



On 08/09/2012 03:47 PM, Roberto Spadim wrote:

explain better..
do you have 2 disks in raid1, and removed one disk, or removed two disks?
could you send dmesg messages?

2012/8/9 Miquel van Smoorenburg [off-list ref]:

quoted

Setup: kernel 3.2.21 (debian testing), mdadm 3.2.5.

I created a RAID1 imsi array on a supermicro server for testing
purposes. I'm trying to see what happens if I hot-remove disks,
hot-add them, reboot, etc to test the resiliency of this setup.

So I removed (by pulling it out) one disk, then simulated adding
a blank replacement disk by putting it back in and running
mdadm --zero-superblock on it.

I re-added it to the container with mdadm /dev/md127 --add /dev/sda..
and now it just sits there. How do I get the RAID1 array (dev/md126)
to start using this disk? The manpage says:

        -a, --add
               hot-add  listed  devices.  If a device appears to have recently
               been part of the array (possibly it failed or was removed)  the
               device  is  re-added  as  described in the next point.  If that
               fails or the device was never part of the array, the device  is
               added  as a hot-spare.  If the array is degraded, it will imme‐
               diately start to rebuild data onto that spare.

However, nothing is happening:

root@server3-b05-tpb:~/tmp# cat /proc/mdstat
Personalities : [raid1]
md126 : active raid1 sdb[0]
       31457280 blocks super external:/md127/0 [2/1] [_U]

md127 : inactive sda[1](S) sdb[0](S)
       6306 blocks super external:imsm


Thanks,

Mike.
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