Re: [Courier-imap] Question about a network/mail setup.

[Jason Williams <jwilliams@courtesymortgage.com>]

> Won't help if the NFS server goes down, although if you have something like
> a NetApp with dual head-ends that wouldn't be a problem. But NFS is a
> dangerous protocol to run over a wide-area network, unless you have it
> entirely hidden behind a VPN. It's a very good solution if you want multiple
> POP/IMAP servers in the same location though.

Hmm...can you expand on the NetApp with dual-head-ends?

I haven't used NFS for awhile, but from what I can recall, it was very 
stable and nice tool to use within a LAN.
However, I could setup a VPN connection between our branch offices that we 
are setting. Our Firewalls have built in support for VPNS and I should be 
able to just create a VPN between each branch with no problems at all. At 
least, in theory that is. :)


> Running multiple servers in different locations but with duplicate copies of
> all messages is a real PITA. If one is really just a 'warm spare', i.e. it
> doesn't receive any IMAP connections until the main server goes down, then
> probably your best bet is to rsync-over-ssh your mail spool from one machine
> to the other periodically.

As it stands now, I have just one mail server running Courier-IMAP. Most of 
our users will be using Netscape and Mozilla clients on Windows Desktops. 
From the meeting I had yesterday, what they wanted to be able to do is this:
If you open up the client, go to Edit -> Mail and Newsgroup Account 
settings -> you can setup an account and at the bottom there is a entry for 
the Local Directory. That is where they want to edit it and point to a 
second server of some sort.
From what I was told, they want to be able to have users email stored in a 
seperate location (i.e. NFS server or whatever) so that in a case that the 
mail server goes down, they have copies of their emails elsewhere that they 
can view. They do not want the emails to be stored locally on the users 
machine as they fear the machine may melt.

Quite possibly, I could point to a NFS share through that location box, 
correct?
One thing I did think of was that im currently running samba with LDAP on 
the backend as a PDC. Each user has a /home share. I could possibly point 
to there for their email, but I think that would be a problem. Reason I 
think so is that the company is growing and if we have 150 people, that 
will not last.


> However, even that needs care; rsync keeps its list of files in RAM. I tried
> rsync'ing 41GB of web sites from one box to another, and it got about half
> way through before running out of RAM and aborting. So you should keep your
> mail spools in chunks of a few GB and rsync them separately.

Good to know.

> There are application-level solutions such as 'isync' you could look at, but
> the disadvantage is that it needs to know your IMAP password in order to
> sync up the mailboxes, and it needs to be run frequently even against
> mailboxes which have not been logged into, for the backup up to date.

I'll take a look at it, see what I can do.

> If you *are* using a Netapp at each site, then snap-mirroring between them
> every 5 minutes is an excellent way to keep a warm backup. Depends how much
> management wants to pay though!! When they see the cost they may think that
> a weekly tape dump with daily incrementals offers a good enough recovery
> scenario; after all, "It's Only E-mail [TM]"
I agree, it is only email. I'm not sure why they came up with this idea all 
of the sudden. Needless to say, I was not happy when I was told this is 
what they wanted to do on such short notice.

snap-mirroring. Where can I find more information on this? What does it 
include?
From what I understand, eventually, they want to be able to do this with 
all of our branch offices, I think. I have a long meeting today to discuss 
this.

Im trying to brainstorm and gather as many ideas as I can. I appreciate 
everyones help and insight here and I look forward to hearing more suggestions.

Cheers,

Jason