On Wed, Jun 26, 2013 at 11:57 AM, Oliver Fuckner <olli@xxxxxxxxxxx> wrote: > How do I debug expander behaviour? I know lsiutil, but is there something > like iostat for sas lanes/phys? Talking about oversubscription: What I > really try is 24 streams to one SSD-mirror. So I will probably need more > ssds, okay... Just by testing simultaneous writes to all your drives and seeing what happens, basically. > > I would test the write behavior of your disks independently of Ceph (but > > simultaneously!) and see what happens. > well dd to the ssds also shows 400MByte/sec with 4MByte blocks. Ah, they're in a RAID-1 mirror with all 24 going to it? Yeah, 24 simultaneous streams is beyond what a lot of controllers and drives can handle very well. Try running multiple streams to the drives and see what their average, deviation, and aggregate bandwidth is. :) I expect that's the issue. -Greg _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
 |