Hello,
My PC suffered a rather nasty case of HW failure recently where the MB
would break the CPU and RAM. I ended up with different data on different
members of my RAID6 array.
I wanted to scan through the drives and take some checksums of various
files in an attempt to ascertain which drives took the most data
corruption damage, to try and find the date that the damage started
occurring (as it was unclear when exactly this began), and to try and
rescue some of the data off of the good pairs.
So I setup the array into read-only mode and started the array with only
two of the drives. Drives 0 and 1. Then I proceeded to try and start a
second pair, drives 2 and 3, so that I could scan them simultaneously.
With the intent of then switching it over to 0 and 2 and 1 and 3, then 0
and 3 and 1 and 2.
This failed with the error message:
# mdadm --assemble -o --run /dev/md128 /dev/sdc /dev/sdd
mdadm: Found some drive for array that is already active: /dev/md127
mdadm: giving up.
# mdadm --detail /dev/md127
Version : 1.2
Creation Time : XXX
Raid Level : raid6
Array Size : XXX
Used Dev Size : XXX
Raid Devices : 4
Total Devices : 2
Persistence : Superblock is persistent
Intent Bitmap : Internal
Update Time : XXX
State : clean, degraded
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : bitmap
Name : XXX
UUID : XXX
Events : 3826931
Number Major Minor RaidDevice State
7 9 0 0 active sync /dev/md0
- 0 0 1 removed
- 0 0 2 removed
6 9 1 3 active sync /dev/md1
Any ideas as to how I can get mdadm to run the array as I requested
above? I did try --force, but mdadm refused to listen.
Thanks,
David
