7.0-Release and 3ware 9550SXU w/BBU - horrible write performance

[Ivan Voras]

Erik Stian Tefre wrote:

> Results from bonnie++ with default settings on my box (7.0-RELEASE,
> amd64, 480 MB system memory, BBU, write cache enabled, 7 drive raid-5,
> storsave = balance, NCQ on):
> 
> Version 1.93d       ------Sequential Output------ --Sequential Input-
> --Random-
> Concurrency   1     -Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
> --Seeks--
> Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
> /sec %CP
> xxxxxxxxxxxxxxxx 1G   275  83 72440  23 24990   6   644  83 76548  15
> 460.6   6

Was the array busy when you did the test? 72-76 MB MB/s is very slow for
a 7-drive array in RAID-5. FreeBSD's disk IO can be sluggish but I doubt
it would get that slow. On a RAID10 array with 6 drives I can get ~~ 200
MB/s in both directions (though on a different controller). RAID5 is
basically striped so your setup should on average yield close to 6 times
the single drive performance, something in the area of 350 MB/s.



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