Re: Load balancers and large deployments?

[Tom Golson <tgolson@tamu.edu>]

Hi Freddie,
     That is mostly true.  When a customer connects to a mail host to login, if the mailhost they connected to isn't the one that their mailbox is on, then the mailserver will send an IMAP or HTTP redirect (depending on the client, of course) to the correct mailhost.  The question becomes, though, how do they connect to the service?  For example, we have mailhost-1/2/3/4 but when people want to log in, they point their browser or client at neo.tamu.edu for the service name.
     What Steve was talking about, was Zimbra including a stand-alone proxy service, or a host that you can assign the service name to, and that's what people connect to in order to get their first re-direct to the mailhost with their mailbox on it.  But since that's not really "baked" yet, you still need to solve the problem of presenting multiple mailstores as a single service name, or making your customers remember the name of their mailstore.
     One option for that, is to use a load-balancer to host the service name, and then redirect different service protocols (SMTP, IMAP, HTTP) to different groups of servers.  Another, very viable option, I believe, is to use DNS round-robin for the service name, but that does add some complexity to the MX record.
     Does that make sense, or was it even what you asked? :-)  

--Tom
     
----- Original Message -----
From: "Freddie Cash" <fjwcash@gmail.com>
To: "zimbra-hied-admins" <zimbra-hied-admins@sfu.ca>
Sent: Friday, June 27, 2008 4:44:17 PM GMT -06:00 US/Canada Central
Subject: Re: Load balancers and large deployments?

On Fri, Jun 27, 2008 at 12:15 PM, Steve Hillman <hillman@sfu.ca> wrote:
> We're doing load balancers as well (F5's), but only for the login page. Once you login, you get directed to "your" mailbox server, which still goes through the load balancer to act as a firewall, but not to do balancing.  SOAP requests for a given user must always be sent to that user's mailbox server, unless you have the HTTP proxy set up, which is introduced in 5.0.5 but is still beta as of 5.0.6
>
> We only have a few hundred users on our system so far (ramping up next month), but we haven't had any reported Zimlet problems.

Doesn't Zimbra come with it's own load-balancing, at least for IMAP
and HTTP?  The admin manual seems to indicate that it does.  The login
box directs the user's connection to their mailbox server, and then
the connection just goes to that server.

I didn't think you could put anything else in front of the mailbox servers.

-- 
Freddie Cash
fjwcash@gmail.com