Xiaoguang, This should be a normal result – the client’s pagecache buffered the write when you dd onto a ceph fs, while no buffering when dd to a rbd. What do you think? Thanks -haifeng On 8/10/10 11:23 AM, "Xiaoguang Liu" <syslxg@xxxxxxxxx> wrote: > on my 2-ods-node cluster, dd can only reach 13MB/s on rbd device. this > is much lower than what I expected. > I can get 30-60 MB/s on a ceph filesystem over the same cluster. > > any idea? > > > > > [root@ceph-1 ~]# dd if=/dev/zero of=/dev/rbd0 bs=1M count=5000 > 5000+0 records in > 5000+0 records out > 5242880000 bytes (5.2 GB) copied, 391.508 s, 13.4 MB/s > -- > 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 > ��.n��������+%������w��{.n����z��u���ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
