On Mon, Dec 1, 2014 at 1:09 PM, Dan Van Der Ster
daniel.vanders...@cern.ch wrote:
Hi Ilya,
On 28 Nov 2014, at 17:56, Ilya Dryomov ilya.dryo...@inktank.com wrote:
On Fri, Nov 28, 2014 at 5:46 PM, Dan Van Der Ster
daniel.vanders...@cern.ch wrote:
Hi Andrei,
Yes, I’m testing from within the
Hi,
After some more tests we’ve found that max_sectors_kb is the reason for
splitting large IOs.
We increased it to 4MB:
echo 4096 cat /sys/block/vdb/queue/max_sectors_kb
and now fio/iostat are showing reads up to 4MB are getting through to the block
device unsplit.
We use 4MB to match the
November, 2014 1:33:20 PM
Subject: Re: [ceph-users] large reads become 512 kbyte reads on
qemu-kvm rbd
Hi,
After some more tests we’ve found that max_sectors_kb is the reason
for splitting large IOs.
We increased it to 4MB:
echo 4096 cat /sys/block/vdb/queue/max_sectors_kb
and now fio
:20 PM
Subject: Re: [ceph-users] large reads become 512 kbyte reads on qemu-kvm rbd
Hi,
After some more tests we’ve found that max_sectors_kb is the reason for
splitting large IOs.
We increased it to 4MB:
echo 4096 cat /sys/block/vdb/queue/max_sectors_kb
and now fio/iostat are showing reads up
On Fri, Nov 28, 2014 at 5:46 PM, Dan Van Der Ster
daniel.vanders...@cern.ch wrote:
Hi Andrei,
Yes, I’m testing from within the guest.
Here is an example. First, I do 2MB reads when the max_sectors_kb=512, and
we see the reads are split into 4. (fio sees 25 iops, though iostat reports
100
On Fri, 28 Nov 2014 08:56:24 PM Ilya Dryomov wrote:
which you are supposed to change on a per-device basis via sysfs.
Is there a way to do this for windows VM's?
--
Lindsay
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___
Oops, I was off by a factor of 1000 in my original subject. We actually have 4M
and 8M reads being split into 100 512kB reads per second. So perhaps these are
limiting:
# cat /sys/block/vdb/queue/max_sectors_kb
512
# cat /sys/block/vdb/queue/read_ahead_kb
512
Questions below remain.
Cheers,
