Re: Raid 10 question/problem [ot]

Jan Engelhardt
2007-01-28T12:41:33Z

On Jan 28 2007 12:05, Michael Tokarev wrote:
>Jan Engelhardt wrote:
>>
>> That's interesting. I am using Aurora Corona, and all but md0 vanishes.
>> (Reason for that is that udev does not create the nodes md1-md31 on
>> boot, so mdadm cannot assemble the arrays.)
>
>This is nonsense.
>
>Mdadm creates those nodes automa[tg]ically - man mdadm, search for --auto.
>Udev has exactly nothing to do with mdX nodes.

Note that `mdadm -As` _is_ run on FC6 boot.

>In order for an md array to be started up on boot, it has to be specified
>in /etc/mdadm.conf. With proper DEVICE line in there. That's all.

That's how it is, and it does not work.

openSUSE 10.2:
no mdadm.conf _at all_, /etc/init.d/boot.d/boot.md is chkconfig'ed _out_,
_no_ md kernel module is loaded, and I still have all the /dev/md nodes.

FC6 standard install:
no mdadm.conf, otherwise regular boot. /dev/md0 exists. Uhuh.

FC6 with two raids:

# fdisk -l
Disk /dev/sdb: 8589 MB, 8589934592 bytes
255 heads, 63 sectors/track, 1044 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdb1 1 123 987966 fd Linux raid autodetect
/dev/sdb2 124 246 987997+ fd Linux raid autodetect
/dev/sdb3 247 369 987997+ fd Linux raid autodetect
/dev/sdb4 370 1044 5421937+ fd Linux raid autodetect

Disk /dev/sdc: 8589 MB, 8589934592 bytes
255 heads, 63 sectors/track, 1044 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdc1 1 123 987966 fd Linux raid autodetect
/dev/sdc2 124 246 987997+ fd Linux raid autodetect
/dev/sdc3 247 369 987997+ fd Linux raid autodetect
/dev/sdc4 370 1044 5421937+ fd Linux raid autodetect

# mdadm -C /dev/md0 -e 1.0 -l 1 -n 2 /dev/sdb1 /dev/sdc1
mdadm: array /dev/md0 started.
# mdadm -C /dev/md1 -e 1.0 -l 1 -n 2 /dev/sdb2 /dev/sdc2
mdadm: error opening /dev/md1: No such file or directory

Showstopper.

# mknod /dev/md1 b 9 1
# mdadm -C /dev/md1 -e 1.0 -l 1 -n 2 /dev/sdb2 /dev/sdc2
mdadm: array /dev/md1 started.
# cat /etc/mdadm.conf
cat: /etc/mdadm.conf: No such file or directory
# echo "DEVICE /dev/sd[a-z][0-9]" >/etc/mdadm.conf
# mdadm --detail --scan >>/etc/mdadm.conf
# cat /etc/mdadm.conf
DEVICE /dev/sd[a-z][0-9]
ARRAY /dev/md0 level=raid1 num-devices=2 name=0 UUID=5ded6a11:3b9072f6:ae46efc7:d1628ea7
ARRAY /dev/md1 level=raid1 num-devices=2 name=1 UUID=2fda5608:d63d8287:761a7a09:68fe743f
# reboot

...
Starting udev: [ OK ]
Loading default keymap (us): [ OK ]
Setting hostname fc6.site: [ OK ]
mdadm: /dev/md0 has been started with 2 drives.
mdadm: error opening /dev/md1: No such file or directory
No devices found
Setting up Logical Volume Management: No volume groups found [ OK ]
...

Now with "DEVICE partitions" in mdadm.conf:

mdadm: /dev/md0 has been started with 2 drives.
mdadm: error opening /dev/md1: No such file or directory

You see, I have all the reason to be confused.

>But in any case, this has exactly nothing to do with kernel.
>It's 100% userspace issues, I'd say distribution-specific issues.

At least I can agree.

-`J'
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