Hello --

I'll try to keep this as brief as I can.

A while back I created an LVM array from 4 1TB Maxtor externals. This LVM
was to serve as a temporary data dump, while two of my internal HDs, were
RMA'd.

During the waiting period, one of the Maxtors failed, and I lost my data.
Having learned my lesson, I pulled the Maxtor for RMA, and resconstructed
the three remaining as a RAID5 array, then created an LVM volume with it.
Lovely.

When the failed Maxtor's replacement returned, I decided to grow the RAID5
array with it. Everything was going fine until one of the other Maxtors
decided to die on me as well. Needless to say I was unimpressed.

The newly-failed unit has been pulled and RMA'd , but I notice that whenever
the just-replaced unit falls asleep, it "falls off" the SCSI chain and
disappears.

Usually, I reboot and then re-assemble the array (this is only temporary
after all), but this time I decided to re-add the device after switching it
off then back on again. Its designation changed from /dev/sdn1
to /dev/sdq1. However, mdadm added it as a spare device, instead of
a "normal" raid component, and of course updated its superblock
accordingly.

Now, I can't start the array at all. mdadm --examine /dev/sdn1 gives:

/dev/sdn1:
Magic : a92b4efc
Version : 00.90.00
UUID : 37e70d06:2fd37f7b:2b41430b:610aafc7
Creation Time : Sun Aug 19 00:33:28 2007
Raid Level : raid5
Used Dev Size : 976767936 (931.52 GiB 1000.21 GB)
Array Size : 2930303808 (2794.56 GiB 3000.63 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 5

Update Time : Sun Nov 4 21:44:14 2007
State : clean
Active Devices : 2
Working Devices : 3
Failed Devices : 1
Spare Devices : 1
Checksum : 6575e3e1 - correct
Events : 0.705392

Layout : left-symmetric
Chunk Size : 32K

Number Major Minor RaidDevice State
this 4 65 1 4 spare

0 0 8 241 0 active sync /dev/sdp1
1 1 0 0 1 faulty removed
2 2 8 225 2 active sync /dev/sdo1
3 3 0 0 3 faulty removed
4 4 65 1 4 spare


"Total Devices" should be 3 not 4, since no spares were specified at
creation time. The drive contents have not been modified, so what I need to
do is change the major/minor number of the drive in the MD superblock. Is
this possible? The "real" major and minor numbers are:
/dev/sdn(8,208) /dev/sdn1(8,209)



All help gratefully received,

Rohan Beckles
rohan.beckles@virgin.net