2011/5/9 Gregory Farnum <gregf@xxxxxxxxxxxxxxx>: > On Sun, May 8, 2011 at 7:43 PM, Simon Tian <aixt2006@xxxxxxxxx> wrote: >> Hi folks, >> >>   ÂI am testing the replication performance of ceph-0.26 with >> libceph, write 1G data in with ceph_write() and read it out with >> ceph_read(), >> >> rep_size  Â1                2 >>  Â3           Â4 >> writeï Â78.8 MB/s        39.38 MB/s       Â27.7 MB/s        20.90 MB/s >> readï  85.3 MB/s        85.33 MB/s       Â78.77MB/s        78.77MB/s >> >> I think if the replication strategy is splay or primary copy, not the >> chain, as the thesis said,  writing speed for 3, 4 or even more >> replication will be a little worse than Â2 replication, should be near >> with 39.38 MB/s. >> But the write performance ÂI got is affect so much by size of replication. >> >> What is the replication strategy in ceph-0.26, not splay? ÂIf splay, >> why not near with 39.38 MB/s? >> >> There is 5 OSDs in 2 hosts, 2 in one and 3 int the other. > > The replication strategy has been fixed at primary copy for several > years now. At expected replication levels (2-3) there just isn't a big > difference between the strategies, and limiting it to primary-copy > replication makes a lot of the bookkeeping for data safety much easier > to handle. As you know, I am a fresh to ceph, haha For primary copy, I think when the replication size is 3, 4, or even more, the writing speed should also near with 2 replication. Because the 2nd, 3rd, 4th, ... replication are written parallelly. The speed I got for 3, 4 replication is not near with the speed of 2, in fact, like linear reduce. Thx very much! -- 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
