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

Lars Ellenberg lars.ellenberg at linbit.com
Thu Jun 6 21:00:20 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 Thu, Jun 06, 2013 at 03:39:19PM +0200, Sebastian Riemer wrote:
> On 04.06.2013 11:56, Lutz Vieweg wrote:
> [...]
> > 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)
> 
> Looks like something in the IO stack above DRBD in the kernel doesn't
> respect the IO size limits of DRBD.
> 
> In kernel 3.3 the function "blk_set_stacking_limits()" has been
> introduced to fix such issues. MD uses this function for example. Before
> that MD used too small IO limits.
> 
> Try these commands and repeat them for the devices above:
> $ cat /sys/block/drbd0/queue/max_sectors_kb
> $ cat /sys/block/drbd0/queue/max_hw_sectors_kb
> 
> Should be 128 as DRBD has 128 KiB hashing functions and can't do bigger
> IO because of that. The kernel internally calculates with 512 byte
> sectors. So 256 sectors are 128 KiB.

At some point you need to update your part of reality, too ;-)
He is talking about DRBD 8.4, and there is no such limitation anymore.

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

DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
__
please don't Cc me, but send to list   --   I'm subscribed



More information about the drbd-user mailing list