On 2020-07-15 17:33, Andrea Gabellini wrote:
Hello list,
I built an email system using a proxy / director pair (IMAP, POP3,
LMTP)
and a backend pair.
To have an HA system, I would like to understand if it is better to use
an NFS export or replication to save emails and index files
NFS is provided by a NAS (in HA), while for replication I would use the
local backend disks
Which of the two systems is more reliable? Are there any drawbacks for
one or the other?
Another option to consider is DRBD replication of the disks at the block
level.
Despite what you might expect, performance and latency is quite good. A
number of years ago I ran such a setup hosting a high traffic MySQL
database, and it worked well. The disks where the limiting factor, not
the network. In my case the two servers where directly connected by one
cable without using a switch or suchlike.
One thing to be aware of with DRBD is that the slave disk is not
accessible at all until you trigger a fail-over, so you can't use it for
read traffic.
--
David Pottage
