> ZIL OPTIONS: Obviously a DDRdrive is the ideal (36k 4k random > IOPS***) but for the same budget I can get 2x Vertex 2 EX 50GB > drives and put each behind it’s own P410 512MB BBWC controller.
The Vertex 2 EX goes for approximately $900 each online, while the P410/512 BBWC is listed at HP for $449 each. Cost wise you should contact us for a quote, as we are price competitive with just a single SSD/HBA combination. Especially, as one obtains 4GB instead of 512MB of ZIL accelerator capacity. > Assuming the SSDs can do 6300 4k random IOPS*** and that the > controller cache confirms those writes in the same latency as the For 4KB random writes you need to look closely at slides 47/48 of the referenced presentation (http://www.ddrdrive.com/zil_accelerator). The 6443 IOPS is obtained after testing for *only* 2 hours post unpackaging or secure erase. The slope of both curves gives a hint, as the Vertex 2 EX does not level off and will continue to decrease. I am working on a new presentation focusing on this very fact for random write IOPS performance over time (life of the device). Suffice to say, 6443 IOPS is *not* worst case performance for random writes on the Vertex 2 EX. > DDRdrive (both PCIe attached RAM?****) then we should have > DDRdrive type latency up to 6300 sustained IOPS. All tests used a QD (Queue Depth) of 32 which will hide the device latency of a single IO. Very meaningful, as real life workloads can be bound by even a single outstanding IO. Let's trace the latency to determine which has the advantage. For the SSD/HBA combination an IO has to run the gauntlet through two controllers (HBA and SSD) and propagate over a SATA cable. The DDRdrive X1 has a single unified controller and no extraneous SATA cable, see slides 15-17. Best regards, Christopher George Founder/CTO www.ddrdrive.com -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
