Help recreating a raid5

Hi

I need to rebuild a 3-disk raid5.

One disk may be faulty (sda) ; one is good (sdd) and the other I think is OK too (sdb).

The array dropped one disk (sda), then a short time later, another (sdb)

I mistakenly 'added' sdb back in which of course marked it as a spare. This means that --assemble even with --force no longer works:

haze:~# mdadm --detail /dev/md1
/dev/md1:
        Version : 00.90.03
  Creation Time : Sat Jun 11 23:12:06 2005
     Raid Level : raid5
    Device Size : 195358336 (186.31 GiB 200.05 GB)
   Raid Devices : 3
  Total Devices : 2
Preferred Minor : 1
    Persistence : Superblock is persistent

Update Time : Sun Apr 2 08:35:50 2006
State : clean, degraded
Active Devices : 1
Working Devices : 2
Failed Devices : 0
Spare Devices : 1

Layout : left-symmetric
Chunk Size : 64K

UUID : 8d3c8cee:ef55096d:0f219d44:189f8912
Events : 0.1285185

Number Major Minor RaidDevice State
0 8 49 0 active sync /dev/sdd1
1 0 0 - removed
2 0 0 - removed

3 8 17 - spare /dev/sdb1

A recent --detail whilst all was well gave:

/dev/md1:

        Version : 00.90.03
  Creation Time : Sat Jun 11 23:12:06 2005
     Raid Level : raid5
     Array Size : 390716672 (372.62 GiB 400.09 GB)
    Device Size : 195358336 (186.31 GiB 200.05 GB)

Raid Devices : 3
Total Devices : 3
Preferred Minor : 1
Persistence : Superblock is persistent

Update Time : Fri Mar 31 09:53:07 2006
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0

Layout : left-symmetric
Chunk Size : 64K

UUID : 8d3c8cee:ef55096d:0f219d44:189f8912
Events : 0.1269558

Number Major Minor RaidDevice State
0 8 49 0 active sync /dev/sdd1
1 8 17 1 active sync /dev/sdb1
2 8 1 2 active sync /dev/sda1

and at the first failure I saw this in dmesg:
raid5: Disk failure on sda1, disabling device. Operation continuing on 2 devices
RAID5 conf printout:
--- rd:3 wd:2 fd:1
disk 0, o:1, dev:sdd1
disk 1, o:1, dev:sdb1
disk 2, o:0, dev:sda1
RAID5 conf printout:
--- rd:3 wd:2 fd:1
disk 0, o:1, dev:sdd1
disk 1, o:1, dev:sdb1

From some archive reading I understand that I can recreate the array using

   mdadm --create /dev/md1 -l5 -n3 /dev/sdd1 /dev/sdb1 missing

but that I need to specify the correct order for the drives.

I've not used --assume-clean, --force or --run; should I? I assume that since it's only got 2 of 3 then it won't need the assume-clean.

The detail and dmesg data suggests that the order in the command above is correct.

Can anyone confirm this?

Thanks

David

Yes, that all looks correct.

NeilBrown

Thanks Neil

That seemed to work.
Now I need to find out if I have bad hardware or if there is something (else) wrong with libata :)

David