[DRBD-user] kernel: drbd0: bio would need to, but cannot, be split:

[Alexandre Biancalana]

On Thu, May 28, 2009 at 8:29 AM, Lars Ellenberg
<lars.ellenberg at linbit.com> wrote:
> On Thu, May 28, 2009 at 01:01:04PM +0200, hans morbus2000 wrote:
>> hello,
>>
>> we have configure "Nested lvm2 on top of drbd" on SLES10 SP2 (with all Updates)
>> Raid5 ->lvm2->drbd->lvm2 with 3 LVs with reiserfs and ocfs2
>> drbd 8.2.6 in primary/primary mode
>>
>> when we mapping LV to Virtual Disk over GUI or command line
>> # xm block-attach <domain id from xm list> /dev/vgmirror/raid dev/xvdb w
>>
>> Everything was going just fine until I tried to test the filesystems in the domU
>>
>> error on DomU
>> kernel: Buffer I/O error on device xvdb1, logical block 838849799
>> kernel: end_request: I/O error, dev xvdb, sector 838849855
>> kernel: Buffer I/O error on device xvdb1, logical block 838849792
>> kernel: Buffer I/O error on device xvdb1, logical block 838849793
>> kernel: end_request: I/O error, dev xvdb, sector 63
>> kernel: end_request: I/O error, dev xvdb, sector 63
>> kernel: end_request: I/O error, dev xvdb, sector 125
>> ...
>>
>> error on Dom0
>> kernel: drbd0: bio would need to, but cannot, be split: (vcnt=8,idx=0,size=4096,sector=1048565439)
>> kernel: drbd0: bio would need to, but cannot, be split: (vcnt=8,idx=0,size=4096,sector=1048565439)
>> kernel: drbd0: bio would need to, but cannot, be split: (vcnt=8,idx=0,size=4096,sector=209715647)
>> kernel: drbd0: bio would need to, but cannot, be split: (vcnt=8,idx=0,size=4096,sector=209715647)
>> ...
>>
>> how can we resolve this problem?
>> is this solved in the release 8.3?
>> can DRBD handle more than one Logical Volume per DRBD device?
>
> http://article.gmane.org/gmane.comp.linux.drbd/15034/
> http://article.gmane.org/gmane.comp.linux.drbd/15589/

Lars,

   Just put add

disk {
    	...
    	max-bio-bvecs 1;
    	...
    }
in drbd.conf solve this issue or is also needed to set

# echo 4 > /sys/block/sdb/queue/max_sectors_kb

?



Best Regards and thank you for the great work !

Alexandre