single to multi-server environment

[hazmitia]

Hi,

I'm looking for a good reference to move from a single server (currently in production at 5.0.10) to a multiserver environment (5.0.10) as follows:

2 x LDAP
2 x Mail
2 x MTA

I already checked the "Multiple-Sever Installation" Document but it's geared towards a new install.

In essence I would like to do the following:

1. Create two ldap replicas and keep the existing master for later decommission.

2. Add two mail servers and point them to the ldap replicas

3. Add two mta's and have the mail servers use them.

4. Move accounts to new servers

5. Disable services on the original server

Thanks in advanced.

[Klug]

You can also create only one LDAP replica.

Then, as you suggested, you create the two MTA and two mailboxes servers and configure them properly.
Then move the accounts to the mailboxes servers.

Then you disable the uneeded services on the existing server (mailbox, MTA) and you can keep the existing server as LDAP master and Logger.

Don't forget to add at least one zimbra-proxy in order to "hide" the multiple mailboxes servers behind it an provide a single URL for all your users login.

[Vladimir]

Multi server install doc says the logger should be install on a mailbox server. Is that just because that how the doc decided or can the logger really be installed on a LDAP server?

[Klug]

logger relies on mailbox stuff (binaries, mysql, etc).

You can have zimbra-logger along with zimbra-mailbox but forbid ZCS to put any account on it (through the CoS).

If you're going multi-server, it's for "performance". I would not put zimbra-logger on the same server than zimbra-ldap.

Just like zimbra-proxy should be, IMHO, on a stand-alone server (or VM, obviously).

[LMStone]

Originally Posted by Klug

You can also create only one LDAP replica.

Is this limitation new? The multi-server install docs talk about several LDAP replicas, and configuring the order via the cli in which other ZCS server query the replicas (and master).

Thanks,
Mark

[mmorse]

Probably meant to say 'master' as currently only one master LDAP server can be set up; this server is authoritative for user information, server configuration, etc. Replica LDAP servers can be defined to improve performance and to reduce the load on the master. All updates are made to the master server and are copied to the replica server(s).

The sizing guide used to recommend utilizing at least a replica per 2-6 MTA's, or per 8-12 mailstores. (Of course there's lots more involved in calculating; number of users, mail traffic, if you query for valid recipients on each email, hardware, and typical usage.

However, we currently don't suggest running more than 6 direct-replicas. (This was based on several support cases dealing with out-of-sync issues in 10+ replica cases. While everyone's situation is different, we have to draw a arbitrary limit based on typical hardware & network communication - or people make crazy 30 replica setups...)

Why? The more replicas you have the more threads there are trying to sync with the only master. If you over-saturate things there's a higher likelihood some replicas will fall behind while others monopolize the master, particularly in a heavy write environment. (Daisy-chaining replicas is another matter.)

Adjusting cache sizes and other tweaks that you'll definitely want to do: Zimbra_OpenLDAP_Server : Performance Tuning Guidelines for Large Deployments - Zimbra :: Wiki

Some very cool stuff coming up on the radar soon: Bug 27872 - Support multi-master LDAP deployment > Bug 21991 - OpenLDAP 2.4 upgrade with BDB 4.7

[Klug]

Originally Posted by mmorse

Probably meant to say 'master' as currently only one master LDAP server can be set up

The initial post asked about creating 2 replicas of current master LDAP then decommission it (the current master).

I'd rather create one replica/slave only and keep the current master as master, that's what I meant.

[premoddev]

Hi All,

My situation is little bit different, Currently I have one Single server install of Zimbra 5.0.10 Network edition which is the only production server having more than 300 mail accounts. I want to add one more server in another location (country) which can share half of the existing mail boxes. I have a site to site Ipsec VPN link between these two locations.

Can anybody suggest a procedure to do this?

thanks in advance

Premod

[Klug]

Even if ZCS is not designed to work this way (it's designed to be "centralised"), it can be achieved quite easily.

In the branch office, you install a new ZCS server with all standard packages (LDAP, MTA, mailstore, spelling) but :
. you point it to the main existing LDAP during installation
. you setup the local LDAP to be a replicate of the main existing one
. you setup the local MTA to send mails either directly through the branch office internet or though the main site connexion (using according smarthost)
. you setup two CoS for your users, with a different default server for each CoS (and will have to do the initial migration of users by hand)

[premoddev]

Hi klug,

Thanks for the response, I also thought this way but I have some more doubts.

First of all, after migrating accounts is it necessary to point new server URL for accessing mails or can we use proxy service in the main server (currently not installed) without modifying client configuration.

Secondly, will it affect the existing calendar synchronization after moving mailboxes from one server to another.

Finally how can I move mailboxes manually?


regards
Premod