Hi there, I don't think that Xiaoguang saw the speed of 30-60 MB/s because of cache effects as the speed should be in the order of at least some hundred MB/s then. Do you agree? Could perhaps someone having an rbd-setup running confirm or reject Xiaoguangs measurements? Best regards Ulrich -----Ursprüngliche Nachricht----- Von: Haifeng Liu <haifeng@xxxxxxxxxxxxx> Gesendet: Aug 10, 2010 7:46:52 AM An: "ceph-devel@xxxxxxxxxxxxxxx" <ceph-devel@xxxxxxxxxxxxxxx> Betreff: Re: RBD performance is not good >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" 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�����r��y���b�X��ǧv�^�){.n�+���z�]z���{ay� ʇڙ�,j��f���h���z� �w��� ���j:+v���w�j�m��������zZ+��ݢj"�� -- 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
