Hi James, ZFS SSD usage behaviour heavly depends on access pattern and for asynch ops ZFS will not use SSD's. I'd suggest you to disable SSD's , create a ram disk and use it as SLOG device to compare the performance. If performance doesnt change, it means that the measurement method have some flaws or you havent configured Slog correctly.
Please note that SSD's are way slower then DRAM based write cache's. SSD's will show performance increase when you create load from multiple clients at the same time, as ZFS will be flushing the dirty cache sequantialy. SO I'd suggest running the test from a lot of clients simultaneously Best regards Mertol Mertol Ozyoney Storage Practice - Sales Manager Sun Microsystems, TR Istanbul TR Phone +902123352200 Mobile +905339310752 Fax +902123352222 Email mertol.ozyo...@sun.com -----Original Message----- From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-boun...@opensolaris.org] On Behalf Of James Lever Sent: Friday, July 03, 2009 10:09 AM To: Brent Jones Cc: zfs-discuss; storage-disc...@opensolaris.org Subject: Re: [zfs-discuss] surprisingly poor performance On 03/07/2009, at 5:03 PM, Brent Jones wrote: > Are you sure the slog is working right? Try disabling the ZIL to see > if that helps with your NFS performance. > If your performance increases a hundred fold, I'm suspecting the slog > isn't perming well, or even doing its job at all. The slog appears to be working fine - at ~800 IOPS it wasn't lighting up the light significantly and when a second was added both activity lights were even more dim. Without the slog, the pool was only providing ~200 IOPS for the NFS metadata test. Speaking of which, can anybody point me at a good, valid test to measure the IOPS of these SSDs? cheers, James _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
