Anything with an iodepth of 1 is going to be (relatively) terrible on RBD.
iodepth=128 results in 300 iops in the same setup. Not much better :)
The forthcoming Octopus release of librbd adds support for sparse copy-up writes [1] when your min OSD release is set to Octopus (reads from the parent image were already sparse-read ops). Using holes was previously not very practical due to the large allocations sizes on the OSD, but with the change to 4KiB minimum block sizes, such a technique would be possible (albeit a breaking change for all older clients controlled via a new feature bit). You also have the ability to control the RBD object sizes and use something smaller than the 4MiB default.
That's good news! Is it already in 15.1.1, can I test it? -- Vitaliy Filippov _______________________________________________ Dev mailing list -- dev@xxxxxxx To unsubscribe send an email to dev-leave@xxxxxxx
