On 7/8/2016 2:34 PM, David Lang wrote:
On Fri, 8 Jul 2016, WK wrote:
On 7/7/2016 7:47 PM, David Lang wrote:
I started with Cyrus. How would Dovecot be any better? Does it have
back-end replication/clustering/failover like Cyrus does? or some
other feature that would let me replicate/split my mail repository?
I routinely have high tens of thousands, to low hundreds of
thousands of mail in a single folder, cyrus handles that well (even
without a SSD), how would Dovecot handle that?
Dovecot has their dsync tool (kind of like rsync for Maildirs).
It works extremely well.
We have a several clients at $dayjob who maintain their IMAP servers
in VMs/HW Servers here and then dsync down to a dovecot/postfix box
at their office. That way, they always have a local copy for when
they are at their office. It cuts down on the junk traffic out the
gateway when you have a limited office internet connection shared by
a bunch of employees.
They also rate limit outbound SMTP from the office mailserver's
outbound queue. The employees can dump email into the queue at line
speed, but the outgoing SMTP doesn't suck all the BW out of the
connection when its a bunch of huge files.
Then of course for mobile and their home, they just point their imap
client at the public VM.
so does this allow for a message to be deleted on the office server
and then have it disappear from the public VM? or is it a one-way sync?
its two way
http://wiki.dovecot.org/Replication
how upt-to-the-minute can this be? (i.e. how long between deleting
things in one place and having them disappear in the other place).
Thinking about fail trees with hundreds of thousands to millions of
messages in them.
I believe there is now a daemon that can track that but I'm pretty sure
we are still using a cronjob that fires off once every 10-30 minutes
depending upon the size/# of users of the server.
You can do it per Maildir and throw a flag to prevent overruns.
As far as performance, I know that some of the clients have extremely
large boxes and it seems to handle that reasonably quickly. We do notice
when there is a huge change, such as someone renaming a folder or moving
files from one large folder to another.
That was one of the reasons we were doing it by Maildir/user and
throwing a flag. If the cronjob came around to the same user and the
process was still going it skipped that one.
So yes, there could be delays, though it seems to track a 'change' file
so its otherwise pretty efficient.
-bill
_______________________________________________
Tech mailing list
Tech@lists.lopsa.org
https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech
This list provided by the League of Professional System Administrators
http://lopsa.org/
