Adam Woodbeck wrote:
Here is the description of the issue I found:
"Qmail was designed for BSD-like filesystems. And it is unreliable under Linux because it assumes that link() is a synchronous operation. This is not the case with EXT2 and ReiserFS. So you have to apply this patch <http://www.jedi.claranet.fr/qmail-link-sync.patch> to avoid losing messages due system crashes. You can run Qmail and ReiserFS without this patch, and never notice the bug, because you have to get a crash at the right time to trigger it. But according to Murphy's law, if your queue contains a highly important message, it will happen :)"
I do not know if it is still relevant. Our servers are on battery backups but we've strictly used qmail for our high volume mail servers running FreeBSD in production. In any case, I was able to build qmail using the syncdir library and everything seemed to work just fine. So better safe than sorry provided everything looks good after thorough testing.
According to Dave Sill's book, BSD's FFS only calls link() synchronously when soft updates are OFF. Most people I have worked with turn soft updates ON, as it greatly improves performance. The book recommends the same patch you mentioned for EXT2 users. I don't use it, however, and have never had a problem. But it's certainly something to consider.
Regards,
Bill
