Date: Fri, 11 Aug 2006 14:51:01 -0700 (PDT) From: "R. B. Riddick" <arne_woerner@yahoo.com> To: freebsd-geom@freebsd.org Subject: geom_raid3 vis-a-vis geom_raid5 Message-ID: <20060811215101.29711.qmail@web30310.mail.mud.yahoo.com>
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Hi! I compared the read and write speed (with raidtest from ports) of geom_raid3 and geom_raid5 and found, that geom_raid5 reads a bit faster (about 22/18), but geom_raid5 writes much slower (about 9/21). An about 50% mix of reads and writes results in even worse results: 12/19 (I mean worse than ((9+22)/2)/19). Btw.: Round-robin mode in geom_raid3 does not change so much... I tested with three disks (PIO4) with 10 concurrent processes (raidtest -n 10). Does somebody know, if I do something wrong in my implementation (a write is done in 2 phases: 1. read 2. write, which might cause a higher latency for a single write request, but that should not matter in case of so many requests)? http://home.tiscali.de/cmdr_faako/geom_raid5.tbz Caching (geom_cache) seems not to help in the non-degraded case with raidtest (since the requests are randomly distributed)... Bye Arne __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
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