Scalable Mail solution with NAS

> > >/export/mailboxes/j/o/h/n/johndoe.mbox

In the past I've actually found that reversing the letters gives
much better randomosity around the directory structure so,
would end up in e/o/d/n/johndoe and you don't take much of a hit for this.

> very costly, though, because of all the recursive directories. Also, you're
> going to end up with some directories very imbalanced, since there are more
> frequently occurring names.

It also makes backups a nightmare. In that case, you'll have to shutdown
the entire mail system before you can backup or you'll have a database
image which won't represent the actual data you have on your NAS.

In a high performance/availability system typical tape/spool based backups
are problematic - with netapp you have a number of options to handle
this [snap mirror etc]. It really depends on your turn over of data which
for mail is usually pretty high. [oh and IBM disks tend to make a huge
difference :-)]. Ofcourse spool type backups are fine for the OS and


i'm currently implementing a largish mail server, and have come up with
what i think is a nice way to deal with scale and redundancy, etc, etc.

what i have done is create a couple DNS zones, which are like:

bob IN CNAME popserver1
john IN CNAME popserver1
bill IN CNAME popserver2

bob IN A ; ipaddr of mailserver1
john IN A ; ipaddr of mailserver1
bill IN A ; ipaddr of mailserver2

then, users are told to set their SMTP to and
to direct their POP/IMAP client at

you might even be able to get away with a single map.

incoming mail should direct to

in any case, using this method, you can now arbitrarily store mailboxes
on any of several machines, even possibly in several locations.

if a server fails, you can quickly redirect the users to another server so
that new mail piles up in their new mailbox, and you can restore the broken
server on a more leisurely pace.

this can be extended to allow users to check their email with a web-based
packet at, or even be shortened so
that they can have personal website

how to implement the actual DNS is left as an exercise of the student.