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@xxxxxxxxx]
Sent: Tuesday, November 14, 2017 5:38 PM
To: Milanov, Radoslav Nikiforov <radonm@xxxxxx>
Cc: Mark Nelson <mnelson@xxxxxxxxxx>; ceph-users@xxxxxxxxxxxxxx
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@xxxxxx> 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@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@xxxxxxxxx]
Sent: Tuesday, November 14, 2017 4:40 PM
To: Mark Nelson <mnelson@xxxxxxxxxx>
Cc: Milanov, Radoslav Nikiforov <radonm@xxxxxx>;
ceph-users@xxxxxxxxxxxxxx
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.
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@xxxxxxxxxxxxxx] On Behalf Of Mark Nelson
> Sent: Tuesday, November 14, 2017 4:04 PM
> To: ceph-users@xxxxxxxxxxxxxx
> 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
>>
>>
>>
>>
>>
>> _______________________________________________
>> ceph-users mailing list
>> ceph-users@xxxxxxxxxxxxxx
>>
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>
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