[ceph-users] Bluestore performance 50% of filestore

Milanov, Radoslav Nikiforov radonm at bu.edu
Thu Nov 16 07:53:40 PST 2017


FYI
Having 50GB bock.db made no difference on the performance.

- Rado

From: David Turner [mailto:drakonstein at gmail.com]
Sent: Tuesday, November 14, 2017 6:13 PM
To: Milanov, Radoslav Nikiforov <radonm at bu.edu>
Cc: Mark Nelson <mnelson at redhat.com>; ceph-users at lists.ceph.com
Subject: Re: [ceph-users] Bluestore performance 50% of filestore


I'd probably say 50GB to leave some extra space over-provisioned.  50GB should definitely prevent any DB operations from spilling over to the HDD.

On Tue, Nov 14, 2017, 5:43 PM Milanov, Radoslav Nikiforov <radonm at bu.edu<mailto:radonm at bu.edu>> wrote:
Thank you,
It is 4TB OSDs and they might become full someday, I’ll try 60GB db partition – this is the max OSD capacity.

- Rado

From: David Turner [mailto:drakonstein at gmail.com<mailto:drakonstein at gmail.com>]
Sent: Tuesday, November 14, 2017 5:38 PM

To: Milanov, Radoslav Nikiforov <radonm at bu.edu<mailto:radonm at bu.edu>>
Cc: Mark Nelson <mnelson at redhat.com<mailto:mnelson at redhat.com>>; ceph-users at lists.ceph.com<mailto:ceph-users at lists.ceph.com>

Subject: Re: [ceph-users] Bluestore performance 50% of filestore

You have to configure the size of the db partition in the config file for the cluster.  If you're db partition is 1GB, then I can all but guarantee that you're using your HDD for your blocks.db very quickly into your testing.  There have been multiple threads recently about what size the db partition should be and it seems to be based on how many objects your OSD is likely to have on it.  The recommendation has been to err on the side of bigger.  If you're running 10TB OSDs and anticipate filling them up, then you probably want closer to an 80GB+ db partition.  That's why I asked how full your cluster was and how large your HDDs are.

Here's a link to one of the recent ML threads on this topic.  http://lists.ceph.com/pipermail/ceph-users-ceph.com/2017-September/020822.html
On Tue, Nov 14, 2017 at 4:44 PM Milanov, Radoslav Nikiforov <radonm at bu.edu<mailto:radonm at bu.edu>> wrote:
Block-db partition is the default 1GB (is there a way to modify this? journals are 5GB in filestore case) and usage is low:

[root at kumo-ceph02 ~]# ceph df
GLOBAL:
    SIZE        AVAIL      RAW USED     %RAW USED
    100602G     99146G        1455G          1.45
POOLS:
    NAME              ID     USED       %USED     MAX AVAIL     OBJECTS
    kumo-vms          1      19757M      0.02        31147G        5067
    kumo-volumes      2        214G      0.18        31147G       55248
    kumo-images       3        203G      0.17        31147G       66486
    kumo-vms3         11     45824M      0.04        31147G       11643
    kumo-volumes3     13     10837M         0        31147G        2724
    kumo-images3      15     82450M      0.09        31147G       10320

- Rado

From: David Turner [mailto:drakonstein at gmail.com<mailto:drakonstein at gmail.com>]
Sent: Tuesday, November 14, 2017 4:40 PM
To: Mark Nelson <mnelson at redhat.com<mailto:mnelson at redhat.com>>
Cc: Milanov, Radoslav Nikiforov <radonm at bu.edu<mailto:radonm at bu.edu>>; ceph-users at lists.ceph.com<mailto:ceph-users at lists.ceph.com>

Subject: Re: [ceph-users] Bluestore performance 50% of filestore

How big was your blocks.db partition for each OSD and what size are your HDDs?  Also how full is your cluster?  It's possible that your blocks.db partition wasn't large enough to hold the entire db and it had to spill over onto the HDD which would definitely impact performance.

On Tue, Nov 14, 2017 at 4:36 PM Mark Nelson <mnelson at redhat.com<mailto:mnelson at redhat.com>> wrote:
How big were the writes in the windows test and how much concurrency was
there?

Historically bluestore does pretty well for us with small random writes
so your write results surprise me a bit.  I suspect it's the low queue
depth.  Sometimes bluestore does worse with reads, especially if
readahead isn't enabled on the client.

Mark

On 11/14/2017 03:14 PM, Milanov, Radoslav Nikiforov wrote:
> Hi Mark,
> Yes RBD is in write back, and the only thing that changed was converting OSDs to bluestore. It is 7200 rpm drives and triple replication. I also get same results (bluestore 2 times slower) testing continuous writes on a 40GB partition on a Windows VM, completely different tool.
>
> Right now I'm going back to filestore for the OSDs so additional tests are possible if that helps.
>
> - Rado
>
> -----Original Message-----
> From: ceph-users [mailto:ceph-users-bounces at lists.ceph.com<mailto:ceph-users-bounces at lists.ceph.com>] On Behalf Of Mark Nelson
> Sent: Tuesday, November 14, 2017 4:04 PM
> To: ceph-users at lists.ceph.com<mailto:ceph-users at lists.ceph.com>
> Subject: Re: [ceph-users] Bluestore performance 50% of filestore
>
> 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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