--On February 9, 2006 10:46:29 AM +0000 David Carter <[EMAIL PROTECTED]> wrote:
Cyrus and Postfix both make very heavy use of fsync() to flush data to disk before they confirm actions back to the sending system. RAID controllers or disk boxes with battery backed writeback cache help lots.
I'll confirm what David and Henrique both posted. Cyrus, postfix, and friends, make a LOT of use of fsync. This will cause a lot of I/O, esp if your RAID doesn't have a write cache. I'd also suggest only using a battery backed write cache.
We see similar behavior on Linux with Cyrus, Postfix, and MailScanner (also running SpamAssassin). If/when we get into a situation where our AX100 or CX200 disable their write caches the mailserver usually pretty much pukes since it's constantly causing sync's.
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