Migrating from Cyrus to Dovecot

[Miloslav Hůla]

Hi,

we are migrating from Cyrus 2.3.7 to Dovecot 2.2.13. We have ~7000 
maildirs with ~500GB. Our goal is to do the migration without users have 
notice and with the shortest service downtime. The users use IMAP (with 
shared folders and ACL), POP3 and sieve filters.

As a first choice, we tried the Dovecot's dsync tool. First tests were 
great, but we are not able to change the Cyrus auth backend for 
migration. Moreover, this migration seems too slow for us.

As a second try, we tried the cyrus2dovecot migrating Perl scripts (and 
their derivates) from Wiki2. More or less they works but we found we 
need more control during the migration.

So, as a third try, we wrote own migrating scripts. And thanks to the 
cyrus2dovecot it wasn't too much complicated. And there are my questions:

A) Files and dirs timestamps
The mtime of email file is important as an internal date as I found on 
Wiki2. But what about timestamps of cur/new/tmp directories or Dovecot's 
internal files line dovecot-uidlist? Do they play some role here?

B) The 128 bit mailbox UID
The Wiki2 speaks about 128 bit mailbox UID at first line of 
dovecot-uidlist. Cyrus preserves only 64 bit UID. Is this mailbox UID 
required by Dovecot? If so, can we use 0000000000000000501100008c4a11c1 
(Cyrus UID padded by zeros)?

C) Format of dovecot-uidlist records
Wiki2 shows two examples:
25006 :1276528487.M364837P9451.kurkku,S=1355,W=1394:2,
25017 W2481 :1276533073.M242911P3632.kurkku:2,F

Which format is preferred? Or what the benefits are?

D) Converting between CRLF and LF
If I understand correctly, Dovecot stores emails with LF only. We have 
all emails with CRLF now on Cyrus and converting them to LF only is a 
little more time consuming. Is there any benefit to do that? Or can we 
live with 'mail_save_crlf' without problems?

E) POP3 backend
I found many informations about IMAP internals but few on POP3 
internals. What do I need to do POP3 migration transparent for user?

Many thanks for any answers.

Regards, Milo