Re: cephfs speed

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[replying to myself]

I set aside cephfs and created an rbd volume. I get the same splotchy throughput with rbd as I was getting with cephfs. (image attached)

So, withdrawing this as a question here as a cephfs issue.

#backingout

peter


Peter Eisch
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v2.10

On 8/30/18, 12:25 PM, "Peter Eisch" <Peter.Eisch@xxxxxxxxxxxxxxx> wrote:

Thanks for the thought. It’s mounted with this entry in fstab (one line, if email wraps it):

cephmon-s01,cephmon-s02,cephmon-s03:/ /loam ceph noauto,name=clientname,secretfile=/etc/ceph/secret,noatime,_netdev 0 2

Pretty plain, but I'm open to tweaking!

peter

From: Gregory Farnum <gfarnum@xxxxxxxxxx>
Date: Thursday, August 30, 2018 at 11:47 AM
To: Peter Eisch <Peter.Eisch@xxxxxxxxxxxxxxx>
Cc: "ceph-users@xxxxxxxxxxxxxx" <ceph-users@xxxxxxxxxxxxxx>
Subject: Re: cephfs speed

How are you mounting CephFS? It may be that the cache settings are just set very badly for a 10G pipe. Plus rados bench is a very parallel large-IO benchmark and many benchmarks you might dump into a filesystem are definitely not.
-Greg

On Thu, Aug 30, 2018 at 7:54 AM Peter Eisch <mailto:Peter.Eisch@xxxxxxxxxxxxxxx> wrote:
Hi,

I have a cluster serving cephfs and it works. It’s just slow. Client is using the kernel driver. I can ‘rados bench’ writes to the cephfs_data pool at wire speeds (9580Mb/s on a 10G link) but when I copy data into cephfs it is rare to get above 100Mb/s. Large file writes may start fast (2Gb/s) but within a minute slows. In the dashboard at the OSDs I get lots of triangles (it doesn't stream) which seems to be lots of starts and stops. By contrast the graphs show constant flow when using 'rados bench.'

I feel like I'm missing something obvious. What can I do to help diagnose this better or resolve the issue?

Errata:
Version: 12.2.7 (on everything)
mon: 3 daemons, quorum cephmon-s01,cephmon-s03,cephmon-s02
mgr: cephmon-s02(active), standbys: cephmon-s01, cephmon-s03
mds: cephfs1-1/1/1 up {0=cephmon-s02=up:active}, 2 up:standby
osd: 70 osds: 70 up, 70 in
rgw: 3 daemons active

rados bench summary:
Total time run: 600.043733
Total writes made: 167725
Write size: 4194304
Object size: 4194304
Bandwidth (MB/sec): 1118.09
Stddev Bandwidth: 7.23868
Max bandwidth (MB/sec): 1140
Min bandwidth (MB/sec): 1084
Average IOPS: 279
Stddev IOPS: 1
Max IOPS: 285
Min IOPS: 271
Average Latency(s): 0.057239
Stddev Latency(s): 0.0354817
Max latency(s): 0.367037
Min latency(s): 0.0120791

peter


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v2.10

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