On Tue, 2 Aug 2005, email builder wrote:
Technically, this should be feasible with just plain DNS load balancing, but
in our current medium/low budget scenario, we don't have the rackspace to
have numerous boxes that are dedicated ONLY to SA/clam, thus our desire is to
figure out a way to *WEIGHT* our spamd balancing.
I've been very happy with DNS load balancing. The frontend mxer runs
tinydns on a local zone "blah.local.domain.com", and an instance of
dnscache with the round-robin patch is pointed to in resolv.conf. While I
thought that the load balancing would be a little "rough", looking at the
stats I sent 17011 messages through #1, 17025 through #2, and 17016
through #3 yesterday. I can also weight this by having multiple records,
ie:
spamd1 gets three identical entries in tinydns
spamd2 gets three identical entries in tinydns
spamd3 gets three identical entries in tinydns
spamd4 gets one entry
that will leave spamd4 seeing about 1/3 the load of the other boxes. It's
not "clustering", but when using the "-d" flag:
-d host
Connect to spamd server on given host. If host resolves to multi-
ple addresses, then spamc will fail-over to the other addresses, if
the first one cannot be connected to.
it should hit another box if one goes down. Or some easy scripting could
remove the appropriate entries from tinydns if one machine stops
responding.
Speaking of low budget, we have three SA boxes, each of which has a 2GHz
AMD processor, 1GB RAM. The first two cost about $550, the last one about
$425. They are pretty crappy boxes with no RAID, etc., but it's cheaper
for me to keep one more box than needed in the equation than to build out
a few "uber spamd" boxes. They are in mini-atx cases, so they barely take
up more room than an equivalent number of 1U boxes. I spawn 30 spamd
children on each. I have been very happy with the performance so far.
I'm surprised there's not a lot of folks out there who have done this
before....?
Maybe they're all cheap like me. :)
Charles
Thanks again!
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