In addition to that, Ceph uses full data journaling — if you have two journals on the OS drive then you'll be limited to what that OS drive can provide, divided by two (if you have two-copy happening). -Greg Software Engineer #42 @ http://inktank.com | http://ceph.com On Mon, Aug 26, 2013 at 2:09 PM, Samuel Just <sam.just@xxxxxxxxxxx> wrote: > I think rados bench is actually creating new objects with each IO. > Can you paste in the command you used? > -Sam > > On Tue, Aug 20, 2013 at 7:28 AM, daniel pol <daniel_pol@xxxxxxxxxxx> wrote: >> Hi ! >> >> Ceph newbie here with a placement question. I'm trying to get a simple Ceph >> setup to run well with sequential reads big packets (>256k). >> This is for learning/benchmarking purpose only and the setup I'm working >> with has a single server with 2 data drives, one OSD on each, journals on >> the OS drive, no replication, dumpling release. >> When running rados bench or using a rbd block device the performance is only >> 35%-50% of what the underlying XFS filesystem can do and when I look at the >> IO trace I see random IO going to the physical disk, while the IO at ceph >> layer is sequential. Haven't tested CephFS yet but expect similar results >> there. >> Looking for advice on how to configure Ceph to generate sequential read IO >> pattern to the underlying physical disk. >> >> Have a nice day, >> Dani >> >> _______________________________________________ >> ceph-users mailing list >> ceph-users@xxxxxxxxxxxxxx >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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