Guy,
Thanks for the input. I'm not sure why that disk is now a spare either. I was hoping that there was some way to re-write that superblock to convince the array it was a good disk. I saw some old (pre-mdadm) advice which mentioned using mkraid to rewrite (all) of the superblocks, but that seems really drastic.
In the worst case, as you mentioned, I would try to start with the other (failed) disk. Most of the data on that drive is fairly static, so I hope to have some good recovery -- assuming the disk is still OK (in the past it has been something like a loose cable, so I'm hopeful).
I'll wait and see if Neil has any advice. *crosses fingers*
Bob
Guy wrote:
Your array had 5 disks, not counting any spares. You need to start the array with at least 4 of the five disks, spares don't help when starting an array.
I don't know why it thinks your disk (hdi1) is a spare. But, that may explain how it was removed from the array. Unless Neil has some magic incantations, I think you are out of luck.
If Neil has no ideas, you could try to start the array with the drive that failed (hdk1), but that will cause corruption of any stripes that have changed since the drive was removed from the array. So, save this option as a last resort. Of course, if hdk1 has failed hard, you will not be able to use it.
Last resort!!! Corruption will occur! mdadm --assemble --force /dev/md0 /dev/hde1 /dev/hdk1 /dev/hdm1 /dev/hdo1
Guy
-----Original Message----- From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid-owner@xxxxxxxxxxxxxxx] On Behalf Of Robert Osiel Sent: Saturday, November 13, 2004 7:36 PM To: linux-raid@xxxxxxxxxxxxxxx Subject: Re: A few mdadm questions
Guy/Neil:
Thanks a lot for the help.
Sorry that I didn't include all of the info in my last message, but this box is off the network right now and doesn't even have a floppy or monitor, so I had to do a little work to get the info out.
I tried to start the array with the 3 good disks and the 1 spare, but I got an error to the effect that 3 good + 1 spare drives are not enough to start the array (see below)
> cat /proc/mdstat Personalities : [linear] [raid0] [raid1] [raid5] [multipath] read_ahead not set unused devices: <none>
> mdadm -D /dev/md0 mdadm: md device /dev/md0 does not appear to be active
> mdadm --assemble --force /dev/md0 /dev/hde1 /dev/hdi1 /dev/hdm1 /dev/hdo1
mdadm: /dev/md0 assembled from 3 drives and 1 spare - not enough to start the array
> cat /proc/mdstat Personalities : [linear] [raid0] [raid1] [raid5] [multipath] read_ahead not set md0: inactive ide/host2/bus0/target0/lun0/part1[0] ide/host4/bus0/target0/lun0/part1[5] ide/host6/bus1/target0/lun0/part1[4] ide/host6/bus0/target0/lun0/part1[3]
Some notes: hdk1 is the disk which failed initially hdi1 is the disk which I removed and which thinks it is a 'spare'
The other three drives report basically identical info, like this: > mdadm -E /dev/hde1
Magic : a92b4efc Version : 00.90.00 UUID : ec2e64a8:fffd3e41:ffee5518:2f3e858c Creation Time : Sun Oct 5 01:25:49 2003 Build Level: raid5 Device Size : 160079488 (152.66 GiB 163.92 GB) Raid Devices : 5 Total Devices : 5 Preferred Minor : 0
Update Time Sat Sep 25 22:07:26 2004 State : dirty Active Devices : 3 Working Devices : 4 Failed Devices : 1 Spare Devices : 1 Checksum : 4ee5cc77 - correct Events : 0.10
Layout : left-symmetric Chunk Size : 128K
Number Major Minor RaidDevice State
this 0 22 1 0 active sync
0 0 22 1 0 active sync
1 1 0 0 1 faulty removed
2 2 56 1 2 faulty /dev/ide/host4/bus0/target0/lun0/part1
3 3 57 1 3 active sync /dev/ide/host4/bus1/target0/lun0/part1
4 4 88 1 4 active sync /dev/ide/host6/bus0/target0/lun0/part1
5 5 34 1 5 spare
Here are the two drives in question:
__________mdadm -E /dev/hdi1:
Magic : a92b4efc Version : 00.90.00 UUID : ec2e64a8:fffd3e41:ffee5518:2f3e858c Creation Time : Sun Oct 5 01:25:49 2003 Build Level: raid5 Device Size : 160079488 (152.66 GiB 163.92 GB) Raid Devices : 5 Total Devices : 5 Preferred Minor : 0
Update Time Sat Sep 25 22:07:26 2004 State : dirty Active Devices : 3 Working Devices : 4 Failed Devices : 1 Spare Devices : 1 Checksum : 4ee5cc77 - correct Events : 0.10
Layout : left-symmetric Chunk Size : 128K
Number Major Minor RaidDevice State
this 5 34 1 5 spare
0 0 22 1 0 active sync
1 1 0 0 1 faulty removed
2 2 56 1 2 faulty /dev/ide/host4/bus0/target0/lun0/part1
3 3 57 1 3 active sync /dev/ide/host4/bus1/target0/lun0/part1
4 4 88 1 4 active sync /dev/ide/host6/bus0/target0/lun0/part1
5 5 34 1 5 spare
__________mdadm -E /dev/hdk1 Magic : a92b4efc Version : 00.90.00 UUID : ec2e64a8:fffd3e41:ffee5518:2f3e858c Creation Time : Sun Oct 5 01:25:49 2003 Build Level: raid5 Device Size : 160079488 (152.66 GiB 163.92 GB) Raid Devices : 5 Total Devices : 5 Preferred Minor : 0
Update Time Sat Sep 25 22:07:24 2004 State : dirty Active Devices : 4 Working Devices : 5 Failed Devices : 0 Spare Devices : 1 Checksum : 4ee5cc77 - correct Events : 0.9
Layout : left-symmetric Chunk Size : 128K
Number Major Minor RaidDevice State
this 2 56 1 2 active sync /dev/ide/host4/bus0/target0/lun0/part1
0 0 22 1 0 active sync
1 1 0 0 1 faulty removed
2 2 56 1 2 active sync /dev/ide/host4/bus0/target0/lun0/part1
3 3 57 1 3 active sync /dev/ide/host4/bus1/target0/lun0/part1
4 4 88 1 4 active sync /dev/ide/host6/bus0/target0/lun0/part1
5 5 34 1 5 spare
Neil Brown wrote:
haveOn Friday November 12, bugzilla@xxxxxxxxxxxxxxxx wrote:
First, stop using the old raid tools. Use mdadm only! mdadm would not
allowed your error to occur.
I'm afraid this isn't correct, though the rest of Guy's advice is very good (thanks Guy!).
mdadm --remove does exactly the same thing as raidhotremove
It is the kernel that should (and does) stop you from hot-removing a device that is working and active. So I'm not quite sure what happened to Robert...
Robert: it is always useful to provide specific with the output of cat /proc/mdstat
and
mdadm -D /dev/mdX
This avoids possible confusion over terminology.
NeilBrown
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