Multi MTA's using Open Source Edition

wskibum · Post by **wskibum** » Fri Mar 10, 2006 4:16 pm

So I've downloaded the Open Source version of Zimbra and I'm rolling up my sleeves to start setting up. I've read the docs on setting up multiple servers and just this morning fired up a box with LDAP, logging and zimbra-store. In that process I note that it asks me for the name of my smtp host. Since it looks like I can only enter 1 server name here, how does that impact having multiple mta's? What would be the correct entry? Right now my plan for testing is to setup 3 servers that should be able to handle about 500 accounts. 1 server for ldap, zimbra-store, & zimbra-logger and 2 servers for zimbra-mta's.

Thanks

marcmac · Post by **marcmac** » Fri Mar 10, 2006 4:18 pm

Two options - you can either load balance them in DNS, or use one MTA for outgoing, and one for incoming.

wskibum · Post by **wskibum** » Fri Mar 10, 2006 4:39 pm

I've never done DNS load balancing. Is there any basic documentation on the procedure?
Thanks

wskibum · Post by **wskibum** » Fri Mar 10, 2006 4:42 pm

Sorry, I also forgot to ask if using dns load balancing what would I put in for the host name? Doesn't look like you can leave it blank.

marcmac · Post by **marcmac** » Fri Mar 10, 2006 4:53 pm

DNS load balancing is to have two "A" records set up in DNS with the same name, and different IPs - DNS queries will return them in a round-robin fashion.
So, you'd set up one name in DNS for both servers, and use that name as your smtp host.

wskibum · Post by **wskibum** » Fri Mar 10, 2006 4:56 pm

Okay, I just did a lookup on dns load balancing. Since my plan was to use round robin on the mta's with a 4th server acting as the head (RedHat's solution) can I just put the name of the head and have both mta's recieve and send mail? Since the only MX record is for the head, right?
-----------------

| Data Server |

-----------------

|

|

---------- ----------

| MTA | - - - - - | - - - - -| MTA |

---------- ----------

|

--------------------

| Round Robin Head |

--------------------

/|

|

INCOMING MAIL

TRAFFIC

/|

|

INCOMING HTTP

TRAFFIC

marcmac · Post by **marcmac** » Fri Mar 10, 2006 4:58 pm

That will work, but you still need to configure an SMTP server for the store server to use as outgoing - if it's looking hte hostname up via DNS (eg, it's not in the /etc/hosts file) use the round-robin name. Otherwise, you have to choose one of the two.

rsharpe · Post by **rsharpe** » Mon Mar 13, 2006 9:01 am

Now it is my understanding that when a round robin record is returned it returns both entries, in some order that can be specified. What happens if the first entry in the returned DNS record is down. Will it automatically try the other entry returned by the query?

marcmac · Post by **marcmac** » Mon Mar 13, 2006 11:13 am

It will probably time out. If you want that behaviour, you'll probably need load-balancing hardware.