Udo,
I was wondering yesterday if aligning the LVM VG to 4MB would provide any performance benefit. My hunch is that it would, much like erasure blocks on SSDs (probably not so much now). I haven't had a chance to test it though. If you do, I'd like to know your results.
On Thu, Dec 18, 2014 at 1:44 AM, Udo Lembke <ulembke@xxxxxxxxxxxx> wrote:
Hi all,
I have some fileserver with insufficient read speed.
Enabling read ahead inside the VM improve the read speed, but it's
looks, that this has an drawback during lvm-operations like pvmove.
For test purposes, I move the lvm-storage inside an VM from vdb to vdc1.
It's take days, because it's 3TB data.
After enbling read ahead (echo 4096 >
/sys/block/vdb/queue/read_ahead_kb; echo 4096 >
/sys/block/vdc/queue/read_ahead_kb) the move-speed drop noticeable!
Are they any tunings to improve speed related to lvm on rbd-storage?
Perhaps, if using partitions, align the partition on 4MB?
Any hints?
Udo
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