> I was under the impression that real-time processes essentially trump all > others, and I'm surprised by this behaviour; I had a dozen or so RT-processes > sat waiting for disc for about 20s.
Process priorities on Solaris affect CPU scheduling, but not (currently) I/O scheduling nor memory usage. > * Is this a ZFS issue? Would we be better using another filesystem? It is a ZFS issue, though depending on your I/O patterns, you might be able to see similar starvation on other file systems. In general, other file systems issue I/O independently, so on average each process will make roughly equal forward process on a continuous basis. You still don't have guaranteed I/O rates (in the sense that XFS on SGI, for instance, provides). > * Is there any way to mitigate against it? Reduce the number of iops > available for reading, say? > Is there any way to disable or invert this behaviour? I'll let the ZFS developers tackle this one .... --- Have you considered using two systems (or two virtual systems) to ensure that the writer isn't affected by reads? Some QFS customers use this configuration, with one system writing to disk and another system reading from the same disk. This requires the use of a SAN file system but it provides the potential for much greater (and controllable) throughput. If your I/O needs are modest (less than a few GB/second), this is overkill. Anton This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
