Hello all, I am new to the list. I have a single machines setup for testing Ceph. It has a dual proc 6 cores(12core total) for CPU and 128GB of RAM. I also have 3 Intel 520 240GB SSDs and an OSD setup on each disk with the OSD and Journal in separate partitions formatted with ext4.
My goal here is to prove just how fast Ceph can go and what kind of performance to expect when using it as a back-end storage for virtual machines mostly windows. I would also like to try to understand how it will scale IO by removing one disk of the three and doing the benchmark tests. But that is secondary. So far here are my results. I am aware this is all sequential, I just want to know how fast it can go. DD IO test of SSD disks: I am testing 8K blocks since that is the default block size of windows. dd of=ddbenchfile if=/dev/zero bs=8K count=1000000 8192000000 bytes (8.2 GB) copied, 17.7953 s, 460 MB/s dd if=ddbenchfile of=/dev/null bs=8K 8192000000 bytes (8.2 GB) copied, 2.94287 s, 2.8 GB/s RADOS bench test with 3 SSD disks and 4MB object size(Default): rados --no-cleanup bench -p pbench 30 write Total writes made: 2061 Write size: 4194304 Bandwidth (MB/sec): 273.004 Stddev Bandwidth: 67.5237 Max bandwidth (MB/sec): 352 Min bandwidth (MB/sec): 0 Average Latency: 0.234199 Stddev Latency: 0.130874 Max latency: 0.867119 Min latency: 0.039318 ----- rados bench -p pbench 30 seq Total reads made: 2061 Read size: 4194304 Bandwidth (MB/sec): 956.466 Average Latency: 0.0666347 Max latency: 0.208986 Min latency: 0.011625 This all looks like I would expect from using three disks. The problems appear to come with the 8K blocks/object size. RADOS bench test with 3 SSD disks and 8K object size(8K blocks): rados --no-cleanup bench -b 8192 -p pbench 30 write Total writes made: 13770 Write size: 8192 Bandwidth (MB/sec): 3.581 Stddev Bandwidth: 1.04405 Max bandwidth (MB/sec): 6.19531 Min bandwidth (MB/sec): 0 Average Latency: 0.0348977 Stddev Latency: 0.0349212 Max latency: 0.326429 Min latency: 0.0019 ------ rados bench -b 8192 -p pbench 30 seq Total reads made: 13770 Read size: 8192 Bandwidth (MB/sec): 52.573 Average Latency: 0.00237483 Max latency: 0.006783 Min latency: 0.000521 So are these performance correct or is this something I missed with the testing procedure? The RADOS bench number with 8K block size are the same we see when testing performance in an VM with SQLIO. Does anyone know of any configure changes that are needed to get the Ceph performance closer to native performance with 8K blocks? Thanks in advance. -- -- *Jason Villalta* Co-founder [image: Inline image 1] 800.799.4407x1230 | www.RubixTechnology.com<http://www.rubixtechnology.com/>
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