Re: Anyone familiar with Apple Xserve RAID - Mailing list pgsql-performance

Kevin Barnard <kbarnard@speedfc.com> writes:

>    Actually you are both are right and wrong.  The XRaid uses
>    FibreChannel to communicate to the host machine(s).  The Raid
>    controller is a FibreChannel controller.  After that there is a
>    FibreChannel to UltraATA conversion for each drive, separate ATA bus
>    for each drive.
>    What I am curious about is if this setup gets around ATA fsync
>    problems, where the drive reports the write before it is actually
>    performed.

Good point.

(a) The FC<->ATA unit hopefully has a battery-backed cache, which
    would make the whole thing more robust against power loss.
(b) Since Apple is the vendor for the drive units, they can buy ATA
    drives that don't lie about cache flushes.  Whether they do or not
    is definitely a question.  ;)

-Doug
--
Let us cross over the river, and rest under the shade of the trees.
   --T. J. Jackson, 1863