Walt Shekrota wrote:

> 2.6.23-gentoo-r3
> built with non mdadm tools
> ie raidtools
> has been working for some time
> Occasionally in upgrades I might have to create devices or raidstart or
> something.
> This is a data only non lvm ext3 raid5 of roughly 144g (3x73g)
> So I recently and perhaps too casually bumped the kernel up to 23 from 21
> worried about some other problem I was having with udev. Yes I'm bleeding
> all over, I hate it when that happens.
> So at boot the volume would normally be mounted as in fstab. Now it stops
> in a shell.
> zoomzoom ~ # raidstart /dev/md0
> cannot determine md version: no MD device file in /dev.
> zoomzoom ~ #
> zoomzoom ~ # cd /dev
> zoomzoom dev # MAKEDEV md
> zoomzoom dev # modprobe md
> zoomzoom dev # raidstart /dev/md0
> /dev/md0: No such device
> zoomzoom dev #
>
> I did see an option in the new 23 kernel not sure if turning it on caused
> this or was possibly fallout from an nfs mount left up at reboot.
> --- Multiple devices driver support (RAID and LVM)
> ? ?
> ? ? <M> RAID support
> ? ?
> ? ? <M> Linear (append) mode
> ? ?
> ? ? < > RAID-0 (striping) mode
> ? ?
> ? ? <M> RAID-1 (mirroring) mode
> ? ?
> ? ? < > RAID-10 (mirrored striping) mode (EXPERIMENTAL)
> ? ?
> ? ? <M> RAID-4/RAID-5/RAID-6 mode
> ? ?
> ? ? [ ] Support adding drives to a raid-5 array
> ? ?
> ? ? <M> Multipath I/O support
> ? ?
> ? ? <M> Faulty test module for MD
> ? ?
> ? ? <M> Device mapper support
> ? ?
> ? ?[*] Device mapper debugging support
> ? ?
> ? ? <M> Crypt target support
> ? ?
> ? ? <M> Snapshot target (EXPERIMENTAL)
> ? ?
> ? ? <M> Mirror target (EXPERIMENTAL)
> ? ?
> ? ? <M> Zero target (EXPERIMENTAL)
>
> see the option for adding drives after raid5? That had been enabled '*'
> and removing it did not change the kernel image.
> If anyone has some safe ideas I'd appreciate it.
> If you read the help on that add drive option it talks about moving data,
> I'd sure hate to think that happened. I think this just showwed in the 23
> kernel.
>


An odd thing is fdisk -l shows the 3 raid5 disks at the end and something
extra
Disk /dev/sdd: 73.4 GB, 73407865856 bytes
255 heads, 63 sectors/track, 8924 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000

Device Boot Start End Blocks Id System
/dev/sdd1 1 8924 71681998+ fd Linux raid
autodetect

Disk /dev/sde: 73.4 GB, 73407865856 bytes
255 heads, 63 sectors/track, 8924 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000

Device Boot Start End Blocks Id System
/dev/sde1 1 8924 71681998+ fd Linux raid
autodetect

Disk /dev/sdf: 73.4 GB, 73407865856 bytes
255 heads, 63 sectors/track, 8924 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000

Device Boot Start End Blocks Id System
/dev/sdf1 1 8924 71681998+ fd Linux raid
autodetect

Disk /dev/dm-0: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000

Disk /dev/dm-0 doesn't contain a valid partition table

What is dm-0?
Thanks.
-Walt