Date: Wed, 8 Dec 2004 11:51:21 -0500 (EST) From: Bill Anderson <anderson@wks.uts.ohio-state.edu> To: <freebsd-performance@freebsd.org> Subject: 2120S poor performance Message-ID: <Pine.GSO.4.33.0412081120520.4974-100000@lennier.uts.ohio-state.edu>
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I've got a 3x72g RAID5 array with U320 disks on an Adaptec 2120S controller under Freebsd 4.10. I'm getting about 25MB/s for sequential reads/writes (e.g. dd if=/dev/aacd0s1b of=/dev/null bs=32k). I've turned on write caching for the container (container set cache /write_cache_enable) and turned off the read caching, per previous posts to this list. I'm going to try setting hw.aac.iosize_max to 96k tonight to see if that helps. I'm currently using an IDE disk that gets about 45MB/s, so I can hardly consider it an "upgrade" to switch to a 25MB/s U320 SCSI system. :/ I've also read that the 2120S is slow because of its design. I'm trying to figure out whether the performance can be increased significantly (I saw a posting of a linux user getting 37.5MB/s, which although still slow might be acceptable), or if I'm better off getting a new card. I'm thinking the latter is the case based on previous postings, but since it will probably be quite expensive to replace it, I wanted to get some more data. What performance should I be expecting from a decent U320 RAID5 controller? Has anyone gotten a 2120S to perform above 30Mb/s in FreeBSD? What's the cheapest controller that still gives reasonable performance? (If you could give a couple different ones, with their associated performance (under FreeBSD), or tell me where to find such information, that would be great) Thanks, Billhome | help
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