Ceph

Running concurrent rados bench processes results in various different problems when performing reads from the same pool. I've seen times where the same objects get almost at the same time resulting in reads from pagecache and other times where IO errors are reported and rados bench dies. I assume that there isn't a distinct object prefix for each rados bench instance's objects.

It would be nice to allow the user to assign one for both writes and reads so that concurrent rados bench instances could be run with their own distinct set of objects and not have to resort to hacks like having individual pools for every single rados bench instance being run. That's what I'm doing now, but it does not scale well once the total number of PGs exceeds a certain number (somewhere in the 80-100k region).