How to update Cyrus IMAP 2.3.16 to 2.4.5

[Lucas Zinato Carraro]

Hi,  I have a cyrus aggregation enviromment.

My frontends are cyrus 2.4.5 ,mupdate  -  cyrus 2.4.5
and have backends with cyrus 2.4.5 and a backend

with 28.000 mailboxes in cyrus 2.3.16.

I test some account with cyus backend 2.4.5 ( ~1000 ) and no problem appear.

Its safe to convert cyrus backend 2.3.16 to cyrus 2.4.5 ?

I know that exist a new index format, its safe to convert  2.3.16 to
2.4.5 ? Any related problem ?

How to perform a safe upgrade ?
    - Install newer version and run reconstruct ?

I see that lmtpd  convert the INBOX index when deliver a new message (
Any bug with this function ? )
and  imapd  convert mailbox index when a client  request access. ( Any
bug with this function ? )

Exist a  "fast reconstruct" ?

In some tests i see that the user lost READ flags from messages. ( all
messages appears as NEW ).
but i dont remember how to reproduce this error.  Anyone discover this
problem ??


And for Rollback:
- Install older version and run reconstruct ?


Regards
Zinato