Hi:
I think I did something wrong and cause mdadm data corruption.
but I am curious which steps brings me down. hope someone can told me
about it.
I have two hosts forms a vm HA cluster. each one is a 2TB * 2
mdadm raid 1. I need to test something but lack of disks, so I pull
one disk of each hosts. after testing, I put the disk back and let
mdadm rebuild. host B took several hours to rebuild and looks fine.
host A took only 5 min to rebuild. after completing rebuild, the
virtual machines stand above the raid crashed one by one. since I
know I have write many data bytes during the testing, host A should
not took only 5 min to recover. I must do something wrong to confuse
mdadm. below is what I done:
1. I test a 3 disk mdadm raid 5: sda (hostA sdb), sdb (hostB sdb), sdc
(new disk). I wrote about 5G data for system restore testing.
2. then I test a 4 disk mdadm raid10: sda (hostA sdb), sdb(hostB
sdb),sdc(new disk),sdd (new disk). I wrote about 5G data for system
restore testing.
3. then I test again a 4 disk mdadm rai10, but wrote about 120G data
for system restore testing.
then I put back the disk to hostA and hostB (hot plugin, HOST A and B
are still running). at hostA I issue command blow:
mdadm --stop /dev/md126; mdadm --stop /dev/md127 (the plugged disk
has raid data on it and udev seems found it)
dd if=/dev/sda of=/dev/sdb bs=1k count=1000 (to recreate mbr
partition table).
partprobe /dev/sdb
mdadm --add /dev/md0 /dev/sdb1 (this is a small 500MB raid for /boot).
mdadm --add /dev/md1 /dev/sdb2 (this is about 2TB raid).
mdadm seems confused it only took 5 min to recover. I did the same
at host B and it took several hours to recover.
so I did something wrong to confuse the mdadm superblock? should I
use "mdadm --zero-superblock /dev/sdb2" before I add it back to mdadm?
thanks a lot for advice!!
Regards,
tbskyd
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