Hi,
We are performing couple performance tests on CephFS using fio. fio is run
in k8s pod and 3 pods will be up running mounting the same pvc to CephFS
volume. Here is command line for random read:
fio -direct=1 -iodepth=128 -rw=randread -ioengine=libaio -bs=4k -size=1G
-numjobs=5 -runtime=500 -group_reporting -directory=/tmp/cache
-name=Rand_Read_Testing_$BUILD_TIMESTAMP
The random read is performed very slow. Here is the cluster log from
dashboard:
5/30/23 8:13:16 PM
[INF]
Health check cleared: MDS_SLOW_REQUEST (was: 1 MDSs report slow requests)
5/30/23 8:13:16 PM
[INF]
Health check cleared: MDS_SLOW_METADATA_IO (was: 1 MDSs report slow
metadata IOs)
5/30/23 8:13:16 PM
[INF]
MDS health message cleared (mds.?): 1 slow metadata IOs are blocked > 30
secs, oldest blocked for 33 secs
5/30/23 8:13:16 PM
[INF]
MDS health message cleared (mds.?): 1 slow requests are blocked > 30 secs
5/30/23 8:13:14 PM
[WRN]
Health check update: 2 MDSs report slow requests (MDS_SLOW_REQUEST)
5/30/23 8:13:13 PM
[INF]
MDS health message cleared (mds.?): 1 slow requests are blocked > 30 secs
5/30/23 8:13:08 PM
[WRN]
Health check failed: 1 MDSs report slow requests (MDS_SLOW_REQUEST)
5/30/23 8:13:08 PM
[WRN]
Health check failed: 1 MDSs report slow metadata IOs (MDS_SLOW_METADATA_IO)
5/30/23 8:13:08 PM
[WRN]
slow request 34.213327 seconds old, received at
2023-05-30T12:12:33.951399+0000: client_request(client.270564:1406144
getattr pAsLsXsFs #0x700000103d0 2023-05-30T12:12:33.947323+0000
caller_uid=0, caller_gid=0{}) currently failed to rdlock, waiting
5/30/23 8:13:08 PM
[WRN]
1 slow requests, 1 included below; oldest blocked for > 34.213328 secs
5/30/23 8:13:07 PM
[WRN]
slow request 33.169703 seconds old, received at
2023-05-30T12:12:33.952078+0000: peer_request:client.270564:1406144
currently dispatched
5/30/23 8:13:07 PM
[WRN]
1 slow requests, 1 included below; oldest blocked for > 33.169704 secs
5/30/23 8:13:04 PM
[INF]
Cluster is now healthy
5/30/23 8:13:04 PM
[INF]
Health check cleared: MDS_SLOW_REQUEST (was: 1 MDSs report slow requests)
5/30/23 8:13:04 PM
[INF]
Health check cleared: MDS_SLOW_METADATA_IO (was: 1 MDSs report slow
metadata IOs)
5/30/23 8:13:04 PM
[INF]
MDS health message cleared (mds.?): 9 slow metadata IOs are blocked > 30
secs, oldest blocked for 45 secs
5/30/23 8:13:04 PM
[INF]
MDS health message cleared (mds.?): 2 slow requests are blocked > 30 secs
5/30/23 8:12:57 PM
[WRN]
2 slow requests, 0 included below; oldest blocked for > 44.954377 secs
5/30/23 8:12:52 PM
[WRN]
2 slow requests, 0 included below; oldest blocked for > 39.954313 secs
5/30/23 8:12:48 PM
[WRN]
Health check failed: 1 MDSs report slow requests (MDS_SLOW_REQUEST)
5/30/23 8:12:47 PM
[WRN]
slow request 34.935921 seconds old, received at
2023-05-30T12:12:12.185614+0000: client_request(client.270564:1406139
create #0x7000001045b/atomic7966567911433736706tmp
2023-05-30T12:12:12.182999+0000 caller_uid=0, caller_gid=0{}) currently
submit entry: journal_and_reply
5/30/23 8:12:47 PM
[WRN]
slow request 34.954254 seconds old, received at
2023-05-30T12:12:12.167281+0000: client_request(client.270564:1406138
rename #0x70000010457/build.xml #0x70000010457/atomic6590865221269854506tmp
2023-05-30T12:12:12.162999+0000 caller_uid=0, caller_gid=0{}) currently
submit entry: journal_and_reply
5/30/23 8:12:47 PM
[WRN]
2 slow requests, 2 included below; oldest blocked for > 34.954254 secs
5/30/23 8:12:44 PM
[WRN]
Health check failed: 1 MDSs report slow metadata IOs (MDS_SLOW_METADATA_IO)
5/30/23 8:12:41 PM
[INF]
Cluster is now healthy
5/30/23 8:12:41 PM
[INF]
Health check cleared: MDS_SLOW_REQUEST (was: 1 MDSs report slow requests)
5/30/23 8:12:41 PM
[INF]
MDS health message cleared (mds.?): 1 slow requests are blocked > 30 secs
5/30/23 8:12:40 PM
[INF]
Health check cleared: MDS_SLOW_METADATA_IO (was: 1 MDSs report slow
metadata IOs)
5/30/23 8:12:40 PM
[INF]
MDS health message cleared (mds.?): 1 slow metadata IOs are blocked > 30
secs, oldest blocked for 38 secs
However, random write test is performing very good.
Any suggestions on the problem?
Thanks,
Ben
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