Giovanni Tirloni <gtirloni <at> sysdroid.com> writes: > > The chassis has 4 columns of 6 disks. The 18 disks I was testing were > all on columns #1 #2 #3.
Good, so this confirms my estimations. I know you said the current ~810 MB/s are amply sufficient for your needs. Spreading the 18 drives across all 4 port multipliers could give you ~972 MB/s. But know that by *removing* 2 drives from the pool you could reach an even higher ~1080 MB/s, because the striped pool is bottlenecked by the slower drives on the congested 3Gbps links, so you are under-using the non-congested 3Gbps links. A 4+4+4+4 config (4 drives on each 3Gbps link, 16 total) would give 300MB/s * 90% / 4 = 67.5 MB/s per drive, times 16 drives = 1080 MB/s. To sum up this thread (your current config is b): (a) 18 drives, HBA in the PCIe 1.0 slot, regardless of PMP config -> 600 MB/s (b) 18 drives, using only 3 PMP (6+6+6+0 config) -> 810 MB/s (c) 18 drives, spread across all 4 PMPs (5+5+4+4 config) -> 972 MB/s (d) 16 drives, more efficient use of all links (4+4+4+4 config) -> 1080 MB/s -mrb _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
