Hi Josh,
i got the following info from the qemu devs.
The discards get canceled by the client kernel as they take TOO long.
This happens due to the fact that ceph handle discards as buffered I/O.
I see that there are max pending 800 requests. And rbd returns success
first when there are no
sorry meant the building in this case. The building of 900 requests
takes too long. So the kernel starts to cancel these I/O requests.
void AioCompletion::finish_adding_requests(CephContext *cct)
{
ldout(cct, 20) AioCompletion::finish_adding_requests
(void*)this pending
Hi Josh,
sorry for the bunch of mails.
It turns out not to be a bug in RBD or ceph but a bug in the linux
kernel itself. Paolo from qemu told me the linux kernel should serialize
these requests instead of sending the whole bunch and then hoping that
all of them get's handling in miliseconds.
But strange enough this works fine with normal iscsi target... no idea why.
Stefan
Am 19.11.2012 11:15, schrieb Stefan Priebe - Profihost AG:
Hi Josh,
sorry for the bunch of mails.
It turns out not to be a bug in RBD or ceph but a bug in the linux
kernel itself. Paolo from qemu told me the
Maybe thats the problem. Finalize gets never called so qemu block driver
doesn't get any feedback and then cancels the io / request.
Stefan
Am 18.11.2012 um 03:38 schrieb Josh Durgin josh.dur...@inktank.com:
On 11/17/2012 02:19 PM, Stefan Priebe wrote:
Hello list,
right now librbd returns
Its done as buffered io. So finalize is only called when buffered is false?
Stefan
Am 18.11.2012 um 03:38 schrieb Josh Durgin josh.dur...@inktank.com:
On 11/17/2012 02:19 PM, Stefan Priebe wrote:
Hello list,
right now librbd returns an error if i issue a discard for a sector /
byterange
mhm ok the finalize is only called if building is false and there are no
pending requests. But the discard issued is a bunch of 1000 requests or
so. So the finalize is only called in the end. And it seems this is too
late for qemu block driver.
Greets,
Stefan
Am 18.11.2012 03:38, schrieb Josh
On 11/17/2012 02:19 PM, Stefan Priebe wrote:
Hello list,
right now librbd returns an error if i issue a discard for a sector /
byterange where ceph does not have any file as i had never written to
this section.
Thanks for bringing this up again. I haven't had time to dig deeper
into it yet,
Hi Josh,
Am 18.11.2012 um 03:38 schrieb Josh Durgin josh.dur...@inktank.com:
On 11/17/2012 02:19 PM, Stefan Priebe wrote:
Hello list,
right now librbd returns an error if i issue a discard for a sector /
byterange where ceph does not have any file as i had never written to
this section.
