>I would Like to configure 2 imail boxes using the same SQL user database via
>ODBC. I have a load balancing switch which will direct traffic to the boxes
>based on availability. I will have the users mail boxes located on a
>mounted file system accessible to both systems.
>Will I run into A read/write issue?
yes, of course. Imail is highly multi-processed, with potentially dozens of
processes running 'simultaneously'. Imail admins have already seen the
"read/write issue" on just one Imail machine, but Imail's processes (SMTP,
POP3, LDAP) competing for access to a mailbox already have mailbox locking
mechanisms. Imail has solved this pb in practice for one machine, and it's
a reasonable extrapolation to think two Imail machines competing for the
same mailbox on an external file server will handle the mailbox locking
equally well, but it's an extrapolation. I don't rememeber seeing anybody
here say they have that running.
>Is this possible?
I think not, based on my guess of what it is you want to achieve.
>I have a load balancing switch which will direct traffic to the boxes
>based on availability.
afaik, you will have the double work of creating and maintaining, manually,
duplication of all mail domains and mailboxes on both machines. There's
no automated replication or mirroring of domains + mailboxes defined on one
Imail machine to another Imail machine. Do you understand this issue?
>I have looked into peering but it doesn't offer the same solution as load
>balancing.
But peering illustrates the pb I point out above: a mail domain and user
account is defined on the Imail machine, as well as in the ODBC database.
Just having two "load balanced" Imail machines sharing 1) an external SQL
database and 2) file-shared mailboxes is not the whole story. (you are
thinking SQL and not MS Access??)
And I'm not sure your load balancing is going to offer you what you want to
achieve.
btw, just what is it that you want to achieve with 'load-balancing'?
1. higher throughput? Then note that probably most Imail machines are
running CPU utilization under 10%? People get stars in their eyes about
becoming "email postmaster of the universe" and typically buy a single,
horrendously overpowered and expensive MailZilla box, only to have it
sitting there handling 200,000 mail accounts with under 5% CPU
utilization. When they should have purchased 3 or 4 smaller machines and
achieved more reliablity and throughput for equal or less outlay.
2. redundancy for availability? DNS + mail gateways are a better way to
achieve reliability and throughput.
Have you used load balancing on other mail systems or is this your first go
at it?
Len
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