ZFS performance question

[Ivan Voras]

On 08/20/10 12:30, Heinrich Rebehn wrote:

> I am somewhat concerned about the numbers for per-char-output and per-char-input. In fact, i have never before seen that low numbers in a bonnie test. Using a single disk with UFS yields about 6 times as much.
> 

> BTW: Running OpenSolaris on the same hardware yields 110306 for per-char-write and 94698 for per-char-read.

"per-char" stats are different between different operating systems
because of how they are implemented. Apparently, bonnie++ forces full
disk writes (fsyncs) for each byte written on BSDs, but Linux (and
apparently Solaris) somehow manage to write-cache this (or at least -
cache it much more). It only matters if you have software which depends
on this caching and performs slowly otherwise.