MURDER : tuning for increasing load

[LaurentG]

Hello,

running CyrusIMAP 2.2.8 on Debian Sarge,  with a murder of 2 frontends &
3 backends, (4 & 4) at the end.

I have to deal with increasing charge of by now 500 users that will grow
up to 100 000.
All mailboxes exist, for a 65Mb mailboxes.db on mupdate

1- Mupdate slows down informing Frontends of changes on backends : on
which parameters do I have to play with ?

2- When updating mailboxes ACLs to relfect LDAP changes with Perl
through Cyrus::IMAP::Admin, got the following error on the backend :

mupdate-client: getaddrinfo (mupdateserver  (null)) failed: Temporary failure in name resolution

while the mupdate was dealing with reservations from backends. I
modified the mupdate master process in cyrus.conf for mupdate processes
with a prefork=50.
I'd need a piece of advice for using correct values for mupdate
parameters in imapd.conf

3- Need also help on correct values for configuring BDB cache a 65Mb
mailboxes.db (Berkeley 3.2) on each type of murder server, as I found
very poor docs on that subject.

If any other point to look at for fine tuning, please tell me.

Thanks in advance for your help (Had no time for real tests under heavy
load so can't test on production platform !!!)

Laurent

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