RE: [cobalt-users] Is Load Balancing and Fall Back Capable

["E.B. Dreger" <eddy+public+spam@xxxxxxxxxxxxxxxxx>]

I> Date: Sun, 17 Nov 2002 17:27:57 -0000
I> From: Ian


I> Right, so for the mail side of life, I need to establish
I> additional MX records within my DNS that is physically
I> provided by the second server, I take it the priority should
I> be set to the highest for the main mail server and low for the
I> backup/second mail server. Thus, if I have the exact same

Actually, this is backwards:  Lowest number is main MX.


I> mail.domain.co.uk on each of the 2 servers, and subsequent
I> vsite and users, then the users of the domain would not know a
I> single thing about it should the primary go down.

Depends on how things are configured.  If mail is not replicated,
consider what happens when pri MX is down and a user tries to
POP.


I> What I do not understand from just doing this. How does the
I> second backup server automatically que the emails for
I> forwarding onto the primary mail server, once it comes back
I> online, i.e. say the backup email server had emails awaiting
I> collection by the users, but the main server came back online
I> before they downloaded it. How would it be sent on
I> automatically once the primary came back online.

It's attempting to relay the messages; hence mail is held in the
queue if the next hop (primary MX) is unavailable.  When it's in
the queue, users cannot POP the messages from the server.


Eddy
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