Re: Ceph RBD performance - random writes

[Mark Kirkwood <mark.kirkwood@catalyst.net.nz>]

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:



$ 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