The notion of 'raw' disk is foreign to Linux. Its a Unixism. The block device
interface is used instead. That isnt optimised for performance however (ie
heavy readahead etc)
> configuration and the stripe size I've used for our drive array, and I
> want to eliminate any variables that depend on other things like buffer
> cache, etc....
If you want to get an accurate disk/controller benchmark you might want to
get Stephen Tweedie's O_DIRECT patches (ftp.linux.org.uk/pub/sct) which
give you what are logically the same thing - uncached I/O from the disk
itself. My only concern is that if FreeBSD does do a copy through kernel
space for its raw devices you may not be making an appropriate comparison
benchmark for some things as Linux would be going userspace->media
Alan
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