Disk 100% busy

[Brad Knowles]

At 1:53 PM -0400 2005-10-16, Will Saxon wrote:

>  I completely forgot that I had the partition mounted 'sync'. That might
>  explain things a bit, huh.

	Perhaps.

>  I am using qmail - the author indicates that softupdates is not
>  recommended. However, I am going to give it a shot and see if I start
>  losing mail as he suggests may happen.

	Soft Updates is only guaranteed to keep your filesystem in a 
consistent state, and does not guarantee that you won't lose a few 
messages.  There are MTAs designed for use on filesystems that use 
Soft Updates, but I don't think qmail is one of them.

	Moreover, qmail was not designed for scalability when handling 
lots of back-end processes such as anti-spam/anti-virus scanning, and 
I believe that it tends to perform badly in those roles.  You can 
configure either postfix or sendmail to be considerably more scalable 
in those kinds of situations than qmail.

	Indeed, with a little careful configuration, with sendmail you 
can avoid virtually all synchronous meta-data updates as far as the 
daemon itself is concerned, and when combined with milter-savvy 
scanning programs, you can pretty much completely avoid them all the 
way up to the point where you have to make final delivery to a user 
mailbox.  That makes for a much more scalable mail system than qmail 
is capable of.


	But then, I'm probably a bit biased since I gave what I believe 
were the first public talks on the subject of building scalable mail 
systems involving such features (see 
<http://www.shub-internet.org/brad/papers/dihses/> and 
<http://www.shub-internet.org/brad/papers/sistpni/>).

-- 
Brad Knowles, <brad at stop.mail-abuse.org>

"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."

     -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
     Assembly to the Governor, November 11, 1755

   SAGE member since 1995.  See <http://www.sage.org/> for more info.