Multi-Server Upgrade Process Question

[LMStone]

We have a client with two mailbox and two MTA servers. One of the mailbox servers is the LDAP master and each of the MTA servers runs an LDAP replica.

Normally when we do a multi-server upgrade we shut all of the Zimbra servers down first before we start by upgrading the LDAP master.

This client however is very keen to minimize downtime, and has asked if the following is doable:

1. Close http/s ports on the firewall and shutdown both mailbox servers.
2. Sever the network connection between the MTA/LDAP replica servers and both mailbox servers.
3. Upgrade the mailbox servers (LDAP master first) while allowing the MTA servers to continue to queue incoming email.
4. After upgrading the mailbox servers (now running), shutdown the MTA servers and close smtp/submission ports on the firewall.
5. Re-establish the network connection between the MTA servers and mailbox servers and upgrade the MTA servers.

We have never done that before ourselves. How does this sound? Has anyone done this before?

Thanks!
Mark

[bdial]

it seems like in theory it should work. we all know how well that goes though. by minimize downtime do they just mean the amount of time other servers arent going to be able to contact their mta servers? because from a user standpoint having the mailbox servers up while you do the mta upgrade doesn't really seem that helpful since they won't receive any of their e-mail from the mta servers and they won't be able to send any e-mail either.

[LMStone]

Thanks for the reply!

The users are domestic and generally check their email during the day. The users' customers are global, and send inbound email throughout the day. Consequently, it is easier to tolerate an outage of the UI at O'Dark-Thirty than it is to bounce inbound email at any time.

I'll keep everyone posted if we try it this way.

All the best,
Mark

[dave_kempe]

If thats what you are trying to acheive it sounds fine. The MTAs should behave like postfix does. We use a secondary MX for most of our domains for this purpose (which is just postfix on another box)

[LMStone]

On our Zimbra hosting farm we too employ a backup MX, in a separate data center, that is a plain Postfix box so no inbound email gets bounced when we are doing a Zimbra upgrade. (Along with some scripts which extract from Zimbra all of the valid email addresses and domains, and which keep the Postfix box automagically up to date with that same info.)

In this case, the client has a premises-based Zimbra solution only, with no off-site non-Zimbra backup MX.

We'll see how it goes!

Thanks Dave!

All the best,
Mark