dovecot - Nov 2013 - Experience with ALTStorage on NFS mount

Hi,

we are thinking about storing older mails (eg. safed before 6 months) to an
alternative storage mounted via NFS
from an external storage box.

Some technical details
- the storage will be connected via 1 gbit ethernet. Access will be allowed from
different dovecot servers, but only to divided directories for each
dovecot.
- storage has the option to use RAID 5 or 6. Max. amount of Disks are 15.
- the index files and the primary storage are just divided in two different
directories and are stored local on SAS disks with RAID 10
- current mail_location config is:
mdbox:/home/vmail/%d/%n:INDEX=/home/dovecotindex/%d/%n
- future mail_location config shoudl look like:
mdbox:/home/vmail/%d/%n:INDEX=/home/dovecotindex/%d/%n:ALT=/home/extstorage/vmail/%d/%n

My question is, if someone of you have already experience in such a setup with
NFS? And are there some tuning tips for NFS?
We have not many experience with NFS right now.

Or perhaps is there some better solution?

Many thanks and regards
Urban

Hi Urban

I would recommend you to use NFS Version 4 and director instances, especially
for such content which is heavily read but seldom written. NFSv4 has way better
client-side caching than older NFS versions. You will need to run idmapd on NFS
server and client to map usernames between server and client and.

Regards
Daniel