This subject has also been on this list a few weeks ago. Look for the subject
"High availability email server"
Quoting Wesley Craig <wes@xxxxxxxxx>:
On 16 Aug 2006, at 14:52, David Korpiewski wrote:
My director had us go back to using our Macs to try to build a
failover cluster. We were able to set up two mail servers sharing
the same backend XSAN. We put our database for cyrus on the XSAN
and had both mail servers use _the same_ database and the same
mail store locations.
So far in limited testing it works flawlessly. This is very
strange to us. Is cyrus set up to allow multiple simultaneous
accesses to its database without corruption or are we just lucky to
not have corrupted the database yet?
This is cyrus 2.2.12 running on two OSX 10.4.7 servers.
The main process which updates mailboxes.db etc on a backend server is
imapd. Since multiple imapd's are allowed, as long as your XSAN
provides appropriate locking, you are not "just lucky". See the
compile documentation for a discussion of how to select the locking
method:
--with-lock=METHOD
Specifies the locking method to use. Currently implemented
locking methods are:
flock flock() locking
fcntl fcntl() locking
By default, configure uses "fcntl" if the "fcntl()" function
exists, "flock" otherwise.
AFAIK, fcntl( ..., F_SETLK*, ...) always locks the whole file, a la
flock(). Also, I think I see a bug in master/service.c, where instead
of using the locking method specified during compile-time, fcntl() is
always used.
:wes
----
Cyrus Home Page: http://asg.web.cmu.edu/cyrus
Cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu
List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
--------------------------------------------------------------------------------
M.Menge Tel.: (49) 7071/29-70316
Universitaet Tuebingen Fax.: (49) 7071/29-5912
Zentrum fuer Datenverarbeitung mail: menge@xxxxxxxxxxxxxxxxxxxx
Waechterstrasse 76
72074 Tuebingen
----
Cyrus Home Page: http://asg.web.cmu.edu/cyrus
Cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu
List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
