An interesting benchmark would be to compare "Ceph SSD journal" + "ext4 on spinner" versus "Ceph without journal" + "ext4 on spinner with external SSD journal". I won't be surprised if the second outperformed the first - you are actually making the whole setup much simpler and Ceph is mostly CPU bound. My bet is on ext4.
Jan > On 07 Aug 2015, at 16:57, Межов Игорь Александрович <me...@yuterra.ru> wrote: > > Hi! > >> No, I was indeed talking about the ext4 journals, e.g. described here: > ... >> but the problem with the persistent device names is keeping me from trying >> it. > > So you assume 3-way setup in Ceph: first drive for filesystem data, second > drive for filesystem journal and third drive for ceph journal? And what is > the benefits? > Ceph journalling already support transactional writes and ext4 journaling > doesn't > improve it anyway. Maybe it is useful to split iops onto a pair devices > instead of one? > It is a too complicated setup, I think. > > > Megov Igor > CIO, Yuterra > > > ________________________________________ > От: ceph-users <ceph-users-boun...@lists.ceph.com> от имени Burkhard Linke > <burkhard.li...@computational.bio.uni-giessen.de> > Отправлено: 7 августа 2015 г. 17:37 > Кому: ceph-users@lists.ceph.com > Тема: Re: [ceph-users] Different filesystems on OSD hosts at the > samecluster > > Hi, > > On 08/07/2015 04:30 PM, Udo Lembke wrote: >> Hi, >> I use the ext4-parameters like Christian Balzer wrote in one posting: >> osd mount options ext4 = "user_xattr,rw,noatime,nodiratime" >> osd_mkfs_options_ext4 = -J size=1024 -E >> lazy_itable_init=0,lazy_journal_init=0 > Thx for the details. >> >> The osd-journals are on SSD-Partitions (without filesystem). IMHO ext4 don't >> support an different journal-device, like >> xfs do, but I assume you mean the osd-jounal and not the filesystem journal?! > No, I was indeed talking about the ext4 journals, e.g. described here: > > http://raid6.com.au/posts/fs_ext4_external_journal_caveats/ > > The setup is tempting (both ext4 + OSD journal on SSD), but the problem > with the persistent device names is keeping me from trying it. > > Regards, > Burkhard > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
