Am 20.06.2009 um 23:26 schrieb NeilBrown:
On Sun, June 21, 2009 12:21 am, Ralf Müller wrote:
Am 19.06.2009 um 03:58 schrieb Neil Brown:
Do you have an idea why this bitmap has been ignored?
Probably a kernel bug. There have been a couple of fixes relating
to
this since 2.6.25. Hopefully it is all working in 2.6.30...
The bug that you hit was probably the one fixed by
commit a0da84f35b25875870270d16b6eccda4884d61a7
which is in 2.6.27.
Just for your information: I updated to OpenSuSE 11.1
(kernel 2.6.27.23-0.1) and tried to remove, grow, re-add the other
devices. For the first disk it worked - re-add took nearly no time
because of the bitmap. For the second disk - it did not work:
complete
resync triggered. No idea why. It has been the same sequence of
commands on the same kind of device. There were no filesystem write
operations on the raid while updating.
Thanks for keeping us informed.
The was another bug related to this that was fixed much more
recently -
in 2.6.30 I think.
commit d0a4bb492772ce5c4bdfba3744a99ed6f6fb238f
I think it was a lot harder to hit, but maybe you hit it.
Ok - when you said it was a lot harder to hit I thought "Hey - hit two
bugs in a row was a great deal, hit a seldom bug a second time ... this
will not happen" and I tried the 4th disk with fail/grow/re-add too.
I hit this bug again ... so it seems having a bitmap at these arrays
saved 10 out of 40 hours for me. Not that impressive ;)
The array does not have a lot of write load (actually write operations
happen in _multi_ GB chunks one to four times a year).
Would there have been a way to update the recorded device-size of
the member devices online? If the fail/grow/re-add cycle would
have worked, I still would have superblocks with the old
size - right?
With a recent kernel, you can write "0" (or some other size
in sectors) to /sys/block/mdX/md/dev-YYY/size, and it will update the
device size online. That functionality appeared in 2.6.26 so
OpenSUSE 11.1 should have it.
It does. And as far as I can say it works. The new device size is
reported in /sys/.../dev-YYY/size and with mdadm -E. So I expect
these values to actually be written to the superblocks.
Regards
Ralf
--
Van Roy's Law: -------------------------------------------------------
An unbreakable toy is useful for breaking other toys.
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
