[ceph-users] Bluestore performance 50% of filestore

Mark Nelson mnelson at redhat.com
Tue Nov 14 13:03:31 PST 2017


Hi Radoslav,

Is RBD cache enabled and in writeback mode?  Do you have client side 
readahead?

Both are doing better for writes than you'd expect from the native 
performance of the disks assuming they are typical 7200RPM drives and 
you are using 3X replication (~150IOPS * 27 / 3 = ~1350 IOPS).  Given 
the small file size, I'd expect that you might be getting better journal 
coalescing in filestore.

Sadly I imagine you can't do a comparison test at this point, but I'd be 
curious how it would look if you used libaio with a high iodepth and a 
much bigger partition to do random writes over.

Mark

On 11/14/2017 01:54 PM, Milanov, Radoslav Nikiforov wrote:
> Hi
>
> We have 3 node, 27 OSDs cluster running Luminous 12.2.1
>
> In filestore configuration there are 3 SSDs used for journals of 9 OSDs
> on each hosts (1 SSD has 3 journal paritions for 3 OSDs).
>
> I’ve converted filestore to bluestore by wiping 1 host a time and
> waiting for recovery. SSDs now contain block-db – again one SSD serving
> 3 OSDs.
>
>
>
> Cluster is used as storage for Openstack.
>
> Running fio on a VM in that Openstack reveals bluestore performance
> almost twice slower than filestore.
>
> fio --name fio_test_file --direct=1 --rw=randwrite --bs=4k --size=1G
> --numjobs=2 --time_based --runtime=180 --group_reporting
>
> fio --name fio_test_file --direct=1 --rw=randread --bs=4k --size=1G
> --numjobs=2 --time_based --runtime=180 --group_reporting
>
>
>
>
>
> Filestore
>
>   write: io=3511.9MB, bw=19978KB/s, iops=4994, runt=180001msec
>
>   write: io=3525.6MB, bw=20057KB/s, iops=5014, runt=180001msec
>
>   write: io=3554.1MB, bw=20222KB/s, iops=5055, runt=180016msec
>
>
>
>   read : io=1995.7MB, bw=11353KB/s, iops=2838, runt=180001msec
>
>   read : io=1824.5MB, bw=10379KB/s, iops=2594, runt=180001msec
>
>   read : io=1966.5MB, bw=11187KB/s, iops=2796, runt=180001msec
>
>
>
> Bluestore
>
>   write: io=1621.2MB, bw=9222.3KB/s, iops=2305, runt=180002msec
>
>   write: io=1576.3MB, bw=8965.6KB/s, iops=2241, runt=180029msec
>
>   write: io=1531.9MB, bw=8714.3KB/s, iops=2178, runt=180001msec
>
>
>
>   read : io=1279.4MB, bw=7276.5KB/s, iops=1819, runt=180006msec
>
>   read : io=773824KB, bw=4298.9KB/s, iops=1074, runt=180010msec
>
>   read : io=1018.5MB, bw=5793.7KB/s, iops=1448, runt=180001msec
>
>
>
>
>
> - Rado
>
>
>
>
>
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