On 09/08/12 11:36, Mark Kirkwood wrote:
On 09/08/12 09:58, Mark Nelson wrote:
For what it's worth, with mostly default settings I was seeing about
8MB/s to dell branded samsung SSDs with 4k IOs using rados bench.
That was with 256 concurrent client requests. This is definitely
something we are working hard on tracking down.
Right (FWIW I think the Dells are actually Toshiba devices - and are
pretty good). This is what I get doing the rados bench for 1M and 4K
blocks:
Sorry Josh - I completely missed the word "Samsung" in your
post...(we've been testing some Dell branded SSD for another project and
it was like giving blood to get the actual brand and model out of them)...
$ rados bench -b 1048576 -t 256 -p rbd 100 write
Total writes made: 3879
Write size: 1048576
Bandwidth (MB/sec): 38.414
Stddev Bandwidth: 40.157
Max bandwidth (MB/sec): 174
Min bandwidth (MB/sec): 0
Average Latency: 6.57279
Stddev Latency: 6.20373
Max latency: 28.531
Min latency: 0.435691
$ rados bench -b 4096 -t 256 -p rbd 100 write
Total writes made: 4851
Write size: 4096
Bandwidth (MB/sec): 0.179
Stddev Bandwidth: 0.378904
Max bandwidth (MB/sec): 3.22266
Min bandwidth (MB/sec): 0
Average Latency: 5.60013
Stddev Latency: 8.18634
Max latency: 22.6542
Min latency: 0.020016
I tried out a raft of xfs config changes and also made the Ceph journal
really big (10G):
$ mkfs.xfs -f -l internal,size=1024m -d agcount=4 /dev/sd[b,c]2
+ mount options with nobarrier,logbufs=8
The results improved a little, but still very slow for small request
sizes...
$ rados bench -b 1048576 -t 256 -p rbd 100 write
Total writes made: 5165
Write size: 1048576
Bandwidth (MB/sec): 50.646
Stddev Bandwidth: 18.8124
Max bandwidth (MB/sec): 205
Min bandwidth (MB/sec): 0
Average Latency: 4.93633
Stddev Latency: 0.549063
Max latency: 5.58999
Min latency: 1.90631
$ rados bench -b 4096 -t 256 -p rbd 100 write
Write size: 4096
Bandwidth (MB/sec): 0.316
Stddev Bandwidth: 0.874144
Max bandwidth (MB/sec): 3.96484
Min bandwidth (MB/sec): 0
Average Latency: 3.16257
Stddev Latency: 11.9167
Max latency: 58.1325
Min latency: 0.017823
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