Migration Pointers?

[Jules Agee]

If you're using Linux for a server of that size, you will definitely 
want an increase from the default number of open files your kernel will 
allow, i.e. put something like this in your rc.local file:

echo 65536 > /proc/sys/fs/file-max

My Cyrus box has ~18000 open files right now with 350 imapd processes 
running, and IIRC the default Linux file-max is 8192.

I talked with a guy from Sendmail, Inc. at LinuxWorld last year and he 
admitted that their IMAP message store was forked from the 1.x Cyrus 
tree a while back. They said they saw large IMAP performance 
improvements when using reiserfs with the 'notail' mount option, versus 
other Linux filesystems. Reiserfs seems to be much more well-optimized 
for situations when you have lots of very small files.

-Jules


Jared Watkins wrote:
> Hello all...
> 
> I'm working on a migration from a single linux Iplanet (aka Netscape aka 
> Sun One) messaging server with Iplanet ldap backend for the user 
> database TO cyrus on linux with an active directory backend.  I have 
> about 2500 accounts on this sytem.. and from the mta logs I go through 
> about 100k messages and 5GB a day of mail volume usually with delivery 
> peaks of no more than 300 messages a minute.  Most users get their mail 
> via pop.. but we will encourage more of them to use imap along with 
> sieve.  We use a wide range of client apps..  all versions of outlook.. 
> outlook express.. eudora.. netscape.. mozilla.. act.. and some others. 
> (This has me most worried)   We also require the use of SSL/TLS for any 
> logins from outside our lan.
> 
> I'm planning to deliver mail via lmtp from our postfix relays... letting 
> them deal with virtual user/domain issues through ldap lookups...  we 
> have only one namespace with the first initial last name style of 
> usernames. 
> I'm already well on my way to finishing some web based cyrus/AD admin 
> tools.. and AD migration scripts...
> 
> Hardware wise... it will be dell on either a dual or quad xenon system.. 
> with 2G of ram.. and either an 7 disk local raid array or a FC attached 
> SAN. 
> For the actual data migration... I have a simple plan.  Since most 
> people use pop..  I'll just cut mail delivery over to the new system.. 
> and provide a page on our intranet for people to move their old mail 
> from one server to the other.. this way I already have their password 
> since they are logged into our intranet.
> 
> Has anyone done a migration like this before?  I'm looking for some 
> gotchas or left field sort of problems I may encounter...  I've  also 
> read some about performance and recovery best practices.. but I'm sure 
> there is more I could learn from all you fine people.  I hope to catch 
> most of the problems through my testing process.. but you never really 
> know what you are going to have problems with until it's in the wild of 
> production.
> 
> Thanks in advance...
> Jared
> 


-- 
Jules Agee
System Administrator
Pacific Coast Feather Co.
julesa at pcf.com      x284