I finally did manage to do this, and the results were a bit interesting. First, the highest amount I saw in the %utilization column was 16% on one server, and that was only there for 1 measurement period. Typical maximums were 7%.
The interesting part was that my second server was rarely over 1%, my first server was 4-7% and my 3rd server was 5-9%. The other interesting part was where the I/O was principally happening. Originally, I had 8TB of 750GB SATA disks (in a hardware raid-6), and then I added a second RAID-6 of 2TB disks which has the majority of the disk space. The two are lvm'ed together. So far, nearly all the %utilization numbers were showing up on the 750GB disks. I have been running xfs_fsr to get the fragmentation down. My 3rd node is still at 17%; the first node is at 5%, and the 2nd node is at 0.7%. I've put in a cron job to run xfs_fsr for 4 hours each Sunday night starting at midnight (when my cluster is usually idle anyway) to try and improve/manage that. I'm not sure if there is actually a causality relationship here, but the load% seems to follow the frag% (higher frag, higher load). Still, the fact that ti peaks out so low has me questioning what's going on... Watching it a bit longer into another workload, and I do see %use spike up to 35%, but network I/O (as measured by bwm-ng) still peaks at 8MB/s on pure gig-e (which should be capable of 90MB/s). --Jim On Thu, Oct 6, 2011 at 1:36 PM, Emmanuel Florac <[email protected]> wrote: > Le Wed, 5 Oct 2011 08:44:11 -0700 vous écriviez: > >> I don't >> know how to watch actual IOPS or other more direct metrics. > > Use the iostat command, something like > > iostat -mx 4 > > you'll have a very detailed report on disk activity. The percentage of > usage (last column to the right) might be interesting. Let it run for a > while and see if there's a pattern. > > -- > ------------------------------------------------------------------------ > Emmanuel Florac | Direction technique > | Intellique > | <[email protected]> > | +33 1 78 94 84 02 > ------------------------------------------------------------------------ > _______________________________________________ Pvfs2-users mailing list [email protected] http://www.beowulf-underground.org/mailman/listinfo/pvfs2-users
