failed to write superblock errors, and more!

I'm wondering what's going on here:

turnip:~ # mdadm /dev/md1 --create --level=1 --bitmap=internal
--raid-devices=2 /dev/sdd1 missing
mdadm: array /dev/md1 started.
turnip:~ # mdadm /dev/md2 --create --level=1 --bitmap=internal
--raid-devices=2 /dev/md1 missing
mdadm: failed to write superblock to /dev/md1
mdadm: array /dev/md2 started.
turnip:~ # mdadm /dev/md2 --stop
turnip:~ # mdadm --zero-superblock /dev/md1
mdadm: Couldn't open /dev/md1 for write - not zeroing
turnip:~ # mdadm /dev/md1 --stop
turnip:~ # mdadm --zero-superblock /dev/sdd1
mdadm: Couldn't open /dev/sdd1 for write - not zeroing
turnip:~ # mdadm /dev/md2 --stop
turnip:~ # mdadm /dev/md2 --stop --force
turnip:~ # ls /sys/block/md1/holders/
md2
turnip:~ #

The kernel is 2.6.34.7-0.7-default (x86_64). openSUSE 11.3.
mdadm 3.0.3

--
Jon
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html

Re: failed to write superblock errors, and more!

On Mon, 14 Feb 2011 22:00:46 -0600 Jon Nelson
wrote:

> I'm wondering what's going on here:
>
> turnip:~ # mdadm /dev/md1 --create --level=1 --bitmap=internal
> --raid-devices=2 /dev/sdd1 missing
> mdadm: array /dev/md1 started.

So far, so good.

> turnip:~ # mdadm /dev/md2 --create --level=1 --bitmap=internal
> --raid-devices=2 /dev/md1 missing
> mdadm: failed to write superblock to /dev/md1

Probably your device is an exact multiple of 64K in size, and is of such a
size that mdadm choose a bitmap size between 60K and 64K. This doesn't fit
and initialising the bitmap fail. Fixed in newer releases.

> mdadm: array /dev/md2 started.

oops. mdadm ignores the error status after printing the 'failed to write
superblock' message. Note added to my to-do list.

> turnip:~ # mdadm /dev/md2 --stop

Normal usage is:
mdadm --stop /dev/md2
Putting them in the other order should either work or give an error message.
It currently does neither. Note added to my to-do list.

Remaining messages are because /dev/md2 is not stopped.

NeilBrown


> turnip:~ # mdadm --zero-superblock /dev/md1
> mdadm: Couldn't open /dev/md1 for write - not zeroing
> turnip:~ # mdadm /dev/md1 --stop
> turnip:~ # mdadm --zero-superblock /dev/sdd1
> mdadm: Couldn't open /dev/sdd1 for write - not zeroing
> turnip:~ # mdadm /dev/md2 --stop
> turnip:~ # mdadm /dev/md2 --stop --force
> turnip:~ # ls /sys/block/md1/holders/
> md2
> turnip:~ #
>
> The kernel is 2.6.34.7-0.7-default (x86_64). openSUSE 11.3.
> mdadm 3.0.3
>

--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html