Molle Bestefich <molle.bestefich <at> gmail.com> writes:
> Karl Voit wrote:
> > if (super == NULL) {
> > fprintf(stderr, Name ": No suitable drives found for %s\n", mddev);
> > [...]
> >
> > Well I guess, the message will be shown, if the superblock is not found.
>
> Yes. No clue why, my buest guess is that you've already zeroed the superblock.
I did, yes. This was because the disks were marked as spare disks and a friend
of mine guessed that zeroing the superblocks might probably erase those
spare-marks and probably the disks can be assembled again. This was after a lot
of testing other methods.
> What does madm --query / --examine say about /dev/sd[abcd], are there
> superblocks ?
root@ned ~ # mdadm --query /dev/md0 /dev/sd[abcd]
/dev/md0: is an md device which is not active
/dev/sda: is not an md array
/dev/sdb: is not an md array
/dev/sdc: is not an md array
/dev/sdd: is not an md array
root@ned ~ # mdadm --query /dev/md0 /dev/sd[abcd]1
/dev/md0: is an md device which is not active
/dev/sda1: is not an md array
/dev/sda1: device 4 in 4 device undetected raid5 /dev/md0. Use \
mdadm --examine for more detail.
/dev/sdb1: is not an md array
/dev/sdb1: device 6 in 4 device undetected raid5 /dev/md0. Use \
mdadm --examine for more detail.
/dev/sdc1: is not an md array
/dev/sdc1: device 5 in 4 device undetected raid5 /dev/md0. Use \
mdadm --examine for more detail.
/dev/sdd1: is not an md array
/dev/sdd1: device 7 in 4 device undetected raid5 /dev/md0. Use \
mdadm --examine for more detail.
root@ned ~ # mdadm --examine /dev/md0 /dev/sd[abcd]
mdadm: No md superblock detected on /dev/md0.
mdadm: No md superblock detected on /dev/sda.
mdadm: No md superblock detected on /dev/sdb.
mdadm: No md superblock detected on /dev/sdc.
mdadm: No md superblock detected on /dev/sdd.
root@ned ~ # mdadm --examine /dev/md0
mdadm: No md superblock detected on /dev/md0.
root@ned ~ # mdadm --examine /dev/sda1
/dev/sda1:
Magic : a92b4efc
Version : 00.90.02
UUID : 15f07005:037e4abf:70f51389:83dde0ed
Creation Time : Sun Jan 29 21:35:05 2006
Raid Level : raid5
Device Size : 244147712 (232.84 GiB 250.01 GB)
Array Size : 732443136 (698.51 GiB 750.02 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Update Time : Sun Jul 2 17:23:03 2006
State : clean
Active Devices : 0
Working Devices : 4
Failed Devices : 0
Spare Devices : 4
Checksum : 4eb2dfe6 - correct
Events : 0.1652541
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 4 8 1 4 spare /dev/sda1
0 0 0 0 0 removed
1 1 0 0 1 faulty removed
2 2 0 0 2 faulty removed
3 3 0 0 3 faulty removed
4 4 8 1 4 spare /dev/sda1
5 5 8 33 5 spare /dev/sdc1
6 6 8 17 6 spare /dev/sdb1
7 7 8 49 7 spare /dev/sdd1
root@ned ~ # mdadm --examine /dev/sdb1
/dev/sdb1:
Magic : a92b4efc
Version : 00.90.02
UUID : 15f07005:037e4abf:70f51389:83dde0ed
Creation Time : Sun Jan 29 21:35:05 2006
Raid Level : raid5
Device Size : 244147712 (232.84 GiB 250.01 GB)
Array Size : 732443136 (698.51 GiB 750.02 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Update Time : Sun Jul 2 17:23:03 2006
State : clean
Active Devices : 0
Working Devices : 4
Failed Devices : 0
Spare Devices : 4
Checksum : 4eb2dffa - correct
Events : 0.1652541
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 6 8 17 6 spare /dev/sdb1
0 0 0 0 0 removed
1 1 0 0 1 faulty removed
2 2 0 0 2 faulty removed
3 3 0 0 3 faulty removed
4 4 8 1 4 spare /dev/sda1
5 5 8 33 5 spare /dev/sdc1
6 6 8 17 6 spare /dev/sdb1
7 7 8 49 7 spare /dev/sdd1
root@ned ~ # mdadm --examine /dev/sdc1
/dev/sdc1:
Magic : a92b4efc
Version : 00.90.02
UUID : 15f07005:037e4abf:70f51389:83dde0ed
Creation Time : Sun Jan 29 21:35:05 2006
Raid Level : raid5
Device Size : 244147712 (232.84 GiB 250.01 GB)
Array Size : 732443136 (698.51 GiB 750.02 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Update Time : Sun Jul 2 17:23:03 2006
State : clean
Active Devices : 0
Working Devices : 4
Failed Devices : 0
Spare Devices : 4
Checksum : 4eb2e008 - correct
Events : 0.1652541
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 5 8 33 5 spare /dev/sdc1
0 0 0 0 0 removed
1 1 0 0 1 faulty removed
2 2 0 0 2 faulty removed
3 3 0 0 3 faulty removed
4 4 8 1 4 spare /dev/sda1
5 5 8 33 5 spare /dev/sdc1
6 6 8 17 6 spare /dev/sdb1
7 7 8 49 7 spare /dev/sdd1
root@ned ~ # mdadm --examine /dev/sdd1
/dev/sdd1:
Magic : a92b4efc
Version : 00.90.02
UUID : 15f07005:037e4abf:70f51389:83dde0ed
Creation Time : Sun Jan 29 21:35:05 2006
Raid Level : raid5
Device Size : 244147712 (232.84 GiB 250.01 GB)
Array Size : 732443136 (698.51 GiB 750.02 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Update Time : Sun Jul 2 17:23:03 2006
State : clean
Active Devices : 0
Working Devices : 4
Failed Devices : 0
Spare Devices : 4
Checksum : 4eb2e01c - correct
Events : 0.1652541
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 7 8 49 7 spare /dev/sdd1
0 0 0 0 0 removed
1 1 0 0 1 faulty removed
2 2 0 0 2 faulty removed
3 3 0 0 3 faulty removed
4 4 8 1 4 spare /dev/sda1
5 5 8 33 5 spare /dev/sdc1
6 6 8 17 6 spare /dev/sdb1
7 7 8 49 7 spare /dev/sdd1
root@ned ~ #
[Unrecognised md component device]
> > Again: this seems to be the case, when the superblock is empty.
>
> Yes, looks like it can't find any usable superblocks.
> Maybe you've accidentally zeroed the superblocks on sd[abcd]1 also?
Yes. But it was on purpose (again after trying a lot of things
without success).
> If you fdisk -l /dev/sd[abcd], does the partition tables look like
> they should / like they used to?
Yes:
root@ned ~ # fdisk -l /dev/sda
Disk /dev/sda: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 1 30395 244147806 fd Linux raid autodetect
root@ned ~ #
... all four of them are exactly the same.
> What does mdadm --query / --examine /dev/sd[abcd]1 tell you, any
> superblocks ?
See above.
> > The problem is also, that without deeper background knowledge, I can not
> > predict, if this or that permanently affects the real data on the disks.
>
> My best guess is that it's OK and you won't loose data if you run
> --zero-superblock on /dev/sd[abcd] and then create an array on
> /dev/sd[abcd]1, but I do find it odd that it suddenly can't find
> superblocks on /dev/sd[abcd]1.
My friend said, that I should try this line
mdadm --create -n 4 -l 5 /dev/md0 missing /dev/sdb1 /dev/sdc1 /dev/sdd1
instead of this line
mdadm --create -n 4 -l 5 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1
first, because when the second one works, it might be the case, that the
raid is starting to synchronize and this might cause problems.
> > Maybe such a person like me starts to think that sw-raid-tools like
> > mdadm should warn users before permanent changes are executed. If
> > mdadm should be used by users (additional to raid-geeks like you),
> > it might be a good idea to prevent data loss. (Ment as a suggestion.)
>
> Perhaps. Or perhaps mdadm should just tell you that you're doing
> something stupid if you try to manipulate arrays on a block device
> which seems to contain a partition table.
Additionally, yes.
> It's not like it's even remotely useful to create an MD array spanning
> the whole disk rather than spanning a partition which spans the whole
> disk, anyway.
I agree. But including best practices into mdadm is not quite an easy
task, I guess.
TNX (again)
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