[Dovecot] Providing shared folders with multiple backend servers

[Sven Hartge]

Hi *,

I am currently in the planning stage for a "new and improved" mail
system at my university.

Right now, everything is on one big backend server but this is causing
me increasing amounts of pain, beginning with the time a full backup
takes.

So naturally, I want to split this big server into smaller ones.

To keep things simple, I want to pin a user to a server so I can avoid
things like NFS or cluster aware filesystems. The mapping for each
account is then inserted into the LDAP object for each user and the
frontend proxy (perdition at the moment) then uses this information to
route each access to the correct backend storage server running dovecot.

So far this has been working nice with my test setup.

But: I also have to provide shared folders for users. Thankfully users
don't have the right to share their own folders, which makes things
easier (I hope).

Right now, the setup works like this, using Courier:

 - complete virtual mail setup
 - global shared folders configured in /etc/courier/shared/index
 - inside /home/shared-folder-name/Maildir/courierimapacl specific user
   get access to a folder
 - each folder a user has access is mapped to the namespace #shared
   like #shared.shared-folder-name

Now, if I split my backend storage server into multiple ones and user-A
is on server-1 and user-B is on server-2, but both need to access the
same shared folder, I have a problem.

I could of course move all users needing access to a shared folder to
the same server, but in the end, this will be a nightmare for me,
because I forsee having to move users around on a daily basis.

Right now, I am pondering with using an additional server with just the
shared folders on it and using NFS (or a cluster FS) to mount the shared
folder filesystem to each backend storage server, so each user has
potential access to a shared folders data.



Ideas? Suggestions? Nudges in the right direction?


Grüße,
Sven.

-- 
Sigmentation fault. Core dumped.