I have been trying to run rados bench runs and I've noticed a lot of variations from run to run. The runs generally write data with --no-cleanup then read it back (seq), dropping the caches in between I admit this is on a single node "cluster" with 5 data disks so maybe not realistic but... In my runs I also collect disk activity traces. When I look at the seq read scores, I've noticed the low scoring runs always have a "hot" disk which maxes out while others might be at 30% to 40% usage. Whereas in the high scoring runs the disk activity is much more evenly distributed. I realize the hashing of objects to primary osds depends on the object names which are different for each run (in rados bench, the object names include the pid). But I was surprised at the sometimes marked unevenness in the hashing. Have others seen this and is there a good workaround? -- Tom Deneau, AMD -- 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
