Hi, i did one experiment which gives some interesting result. i create two OSD (ext4), each is a SSD attached on the same PC. i also configure one monitor and one mds on that PC. so generally, my OSDs, monitor and mds locate on the same node. i set up the ceph service and mount the ceph also on a local directory on that PC. so client, OSDs, monitor and mds all on the same node. i suppose this will exclude the network communication cost. i run fio benchmark which create one 10GB file (larger than main memory) on the ceph mount point. it perform sequential read/write and random read/write on the file, and generate the throughput result. next i umount the ceph and stop ceph service. i create ext4 on the same SSD that used as OSD before. then run the same workloads and get the throughput result. here are the results: (throughput kb/s)Seq-read Rand-read Seq-write Rand-write ceph 7378 4740 790 1211 ext4 58260 17334 54697 34257 as you see, the ceph has huge performance down, even monitor, mds, client and osds locate on the same physical machine. another interesting thing is the seq-write has lower throughput compared with random-write under ceph. not quite clear.... does anyone have idea about why ceph has that performance down? Thanks, Sheng -- Sheng Qiu Texas A & M University Room 332B Wisenbaker email: herbert1984106@xxxxxxxxx College Station, TX 77843-3259 -- 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
