[DRBD-user] "kernel: bio too big device drbd0"

Lars Ellenberg lars.ellenberg at linbit.com
Thu Jun 6 14:51:46 CEST 2013

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On Tue, Jun 04, 2013 at 11:56:34AM +0200, Lutz Vieweg wrote:
> Hi,
> I recently increased the size of a DRBD, first increasing the
> underlying Logical Volume with a command like
>  lvresize --nofsck --extents N DataVG/DataLV
> then I invoked
>  drbdadm resize ResourceData
> and finally
>  cryptsetup resize cryptedResourceData
> to also increase the size of a LUKS device that exists
> on top of the drbd0 device.
> The procedure so far worked fine, I should also mention that
> the same procedure worked fine some years ago for a preceding
> capacity increase.
> The filesystem that resides on the LUKS device has not yet
> been increased in size, because of this bug:
>  https://bugzilla.redhat.com/show_bug.cgi?id=909602
> so the filesystem resize will need to wait for a kernel
> update (planned soon).
> Last time we added capacity, the xfs_grow went fine.
> What concerns me is that after the resizing, /var/log/messages
> accumulated a few dozen of these messages (only on the primary):
> >Jun  4 10:56:40  kernel: bio too big device drbd0 (304 > 256)
> >Jun  4 10:56:40  kernel: bio too big device drbd0 (264 > 256)
> >Jun  4 10:56:40  kernel: bio too big device drbd0 (384 > 256)
> >Jun  4 10:56:42  kernel: bio too big device drbd0 (512 > 256)
> >Jun  4 10:57:05  kernel: bio too big device drbd0 (512 > 256)
> >Jun  4 11:12:07  kernel: bio too big device drbd0 (376 > 256)

You did something bad, and that confused the IO stack.
This causes IO errors.

> The system does not yet show any abnormal behaviour, it has
> been running busy for some days after the first of those messages
> appeared.
> Should I be worried?

Yes, I'd be worried, if I've seen IO errors logged at the kernel level,
but no service nor application noticed them.


> (A "verify" is currently running at 80%, no differences have been found
>  to the secondary so far.)
> [This is not directly related to my recent question about compiling
>  drbd-8.4.3 for linux-3.9.4, the observation is from a different
>  server that is currently running linux 3.7.6 with drbd-8.4]

: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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