> >> NeilBrown
> >
> > I have exactly the same situation, except there are two "failed"
> > disks on a RAID5 array. As for the OP, the "failures" are spurious.
> > Running the remove and then the add command puts the disks back in as
> > spare
> > disks, not live ones, and then the array just sits there, doing nothing.
> > I
> > tried the trick of doing
> >
> > echo repair > /sys/block/md0/md/sync_action
> >
> > but the array still just sits there saying it is "clean, degraded", with
> 2
> > spare and 5 working devices.
> >
>
> No such a good option when you have two failures.
> If you have two failures you need to stop the array, then assemble
> it again using --force.
> It is now too late for that: adding them with "--add" will have erased
> the old metadata.
>
> Your only option is to re-create the array. Make sure you use the
> same parameters (e.g. chunk size) as when you first created the array.
> You can check the correct parameters by looking at a device with
> "--examine".
> Also make sure you put the devices in the correct order.
>
> The best thing to do is to try creating the array, using
> "--assume-clean" so it won't trigger a resync.
> Then use "fsck", the "mount" to make sure the data is good.
> Once you are satisfied that the data is good and that you created
> the array with the right parameters, use "echo repair > ...."
> to make sure the array really is 'clean'.
>
> I guess I should stop mdadm from trashing the superblock when you
> add a spare to an array which has failed....
>
> NeilBrown
OK, Neil, I've had this occur again. A prolonged power failure took one of
the systems offline, and now it's convicting 3 of 7 disks in a RAID5 array.
I've done nothing but stop the array. Prior to stopping the array, mdadm
reported:
Backup:/# mdadm -Dt /dev/md0
/dev/md0:
Version : 01.02
Creation Time : Sun Jul 12 20:44:02 2009
Raid Level : raid5
Array Size : 8790830592 (8383.59 GiB 9001.81 GB)
Used Dev Size : 2930276864 (2794.53 GiB 3000.60 GB)
Raid Devices : 7
Total Devices : 7
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Sun Aug 2 04:01:52 2009
State : clean, degraded
Active Devices : 4
Working Devices : 4
Failed Devices : 3
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 256K
Name : 'Backup':0
UUID : 940ae4e4:04057ffc:5e92d2fb:63e3efb7
Events : 14
Number Major Minor RaidDevice State
0 8 80 0 active sync /dev/sdf
1 8 96 1 active sync /dev/sdg
2 8 0 2 active sync /dev/sda
3 8 16 3 active sync /dev/sdb
4 0 0 4 removed
5 0 0 5 removed
6 0 0 6 removed
4 8 32 - faulty spare /dev/sdc
5 8 48 - faulty spare /dev/sdd
6 8 64 - faulty spare /dev/sde
The array did have a bitmap, but mdadm didn't report it. When I
attempt using --assemble and --force, I get:
Backup:/# mdadm --assemble --force /dev/md0
mdadm: /dev/md0 not identified in config file.
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