Create Raid6 with 1 missing member fails
I tried to create a raid6 with one missing member, but it fails.
It works fine to create a raid6 with two missing members. Is it supposed to be like that ?
mdadm -C /dev/md0 -n5 -l6 -c256 /dev/sd[bcde]1 missing
raid5: failed to run raid set md0
mdadm: RUN_ARRAY failed: Input/output error
mdadm: stopped /dev/md0
mdadm --version
mdadm - v2.6.4 - 19th October 2007
uname -a
Linux compaq2.lan 2.6.23.15-137.fc8 #1 SMP Sun Feb 10 17:03:13 EST 2008 x86_64 x86_64 x86_64 GNU/Linux
mdadm --examine /dev/sdb1/dev/sdb1:
Magic : a92b4efc
Version : 00.90.00
UUID : e4147673:e22e02ac:09e8c875:b3e364c1
Creation Time : Sun Feb 17 14:31:55 2008
Raid Level : raid6
Used Dev Size : 488295424 (465.67 GiB 500.01 GB)
Array Size : 1464886272 (1397.02 GiB 1500.04 GB) Raid Devices : 5
Total Devices : 5
Preferred Minor : 0
Update Time : Sun Feb 17 14:31:55 2008
State : active
Active Devices : 4
Working Devices : 4
Failed Devices : 1
Spare Devices : 0
Checksum : d9c93170 - correct
Events : 0.1
Chunk Size : 256K
Number Major Minor RaidDevice State
this 0 8 17 0 active sync /dev/sdb1
0 0 8 17 0 active sync /dev/sdb1 1 1 8 33 1 active sync /dev/sdc1 2 2 8 49 2 active sync /dev/sdd1 3 3 8 65 3 active sync /dev/sde1 4 4 0 0 4 faulty
Quoted 3 lines · On Sunday February 17, [email protected] wrote:
I tried to create a raid6 with one missing member, but it fails. It works fine to create a raid6 with two missing members. Is it supposed to be like that ?
No, it isn't supposed to be like that, but currently it is.
The easiest approach if to create it with 2 drives missing, and the extra drive immediately.
This is essentially what mdadm will do when I fix it.
Alternately you can use --assume-clean to tell it that the array is clean. It is actually a lie, but it is a harmless lie. Whenever any data is written to the array, that little part of the array will get "cleaned". (Note that this isn't true of raid5, only of raid6).
NeilBrown