Hi, > Correct, but that's the theoretical maximum I was referring to. If I calculate that I should be able to get 50MB/second then 30MB/second is acceptable but 500KB/second is not :) I have written a small benchmark for RBD : https://gist.github.com/smunaut/5433222 It uses the librbd API directly without kernel client and queue requests long in advance and this should give an "upper" bound to what you can get at best. It reads and writes the whole image, so I usually just create a 1 or 2 G image for testing. Using two OSDs on two distinct recent 7200rpm drives (with journal on the same disk as data), I get : Read: 89.52 Mb/s (2147483648 bytes in 22877 ms) Write: 10.62 Mb/s (2147483648 bytes in 192874 ms) The raw disk do about 45 Mo/s when written by 1M chunk. But when written by 4k chunk, this falls to ~500 ko/s ... # dd if=/dev/zero of=/dev/xen-disks/test bs=1M oflag=direct 2049+0 records in 2048+0 records out 2147483648 bytes (2.1 GB) copied, 49.3943 s, 43.5 MB/s # dd if=/dev/zero of=/dev/xen-disks/test bs=4k oflag=direct ^C61667+0 records in 61667+0 records out 252588032 bytes (253 MB) copied, 539.123 s, 469 kB/s Cheers, Sylvain -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
