> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- > boun...@opensolaris.org] On Behalf Of Christopher George > > Jump to slide 37 for the write IOPS benchmarks: > > http://www.ddrdrive.com/zil_accelerator.pdf
Anybody who designs or works with NAND (flash) at a low level knows it can't possibly come close to the sustainable speed of ram, except in corner cases where all the stars are aligned perfectly in favor of the NAND. Think how fast your system can fill its system ram, and then think how fast it can fill an equivalently sized hard drive. If bus speed was actually the limiting factor (and it isn't for any SSD that I know) ... You've got NUMA to system ram, you've got NUMA to PCIe to DDRDrive, and you've got NUM to PCIe to SATA to the SSD. Where you can't even fully utilize the SATA bus because the SSD can't keep up. The above result isn't the slightest bit surprising to me. The SSD manufacturers report maximum statistics that aren't typical or sustainable under anything resembling typical usage. I think the SSD's can actually live up to their claims if (a) they have a read-mostly workload, and either (b)(1) they have large sequential operations mostly, or (b)(2) they have random operations which are suitably sized to match the geometry of the NAND cells internally. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
