[Dovecot] Complete migration from Cyrus on remote server

[lst_hoe02 at kwsoft.de]

Zitat von Alan McGinlay - SICS <alanm at sics.se>:

> Hi All!
>
> I am working on a complete migration from an old solaris machine
> running Cyrus IMAP v2.3.14 and wish to migrate all users to a new ubuntu
> vm running Dovecot 2.0.19.
>
> What I have so far is a fully functional dovecot installation with LDAP
> / Dovecot SASL auth using Maildir++.
>
> My plan is to use Perdition IMAP proxy on a third host and migrate
> users a few at a time (see attached picture of my whiteboard).
>
> The proxy is in place and already used by webmail clients to connect to
> the old server, shortly I will change the dns to point smtp.domain.com
> and imap.domain.com etc to the proxy instead of the old server but I
> haven't finished testing yet. Once that is done it is a simple matter of
> changing the proxy configuration per user to make them hit the new
> server instead.
>
> The problem I am having with this is that I am using Imapsync
> (http://imapsync.lamiral.info) to perform the initial synchronization (i
> have scripted it to maintain sync every 10 minutes with the addtion of
> "--maxage 1" option) using the following command line options:
>
> /usr/local/bin/imapsync  --noreleasecheck --useheader ALL --delete2
> --expunge2 --tmpdir /var/vmail/cache --subscribe --subscribed --tls1
> --tls2 --usecache --nofoldersizes --nocheckmessageexists --host1
> oldserver.domain.com --authuser1 adminuser --user1 testuser at domain.com
> --authmech1 PLAIN --password1 <HIDDEN> --host2 newserver.domain.com
> --authuser2 adminuser --user2 testuser at domain.com --authmech2 PLAIN
> --password2 <HIDDEN>
>
> All email is copied over and stored in dovecot as you would expect.
> Then I switch the user to the new server on the imapproxy and restart
> the client (thunderbird or whatever). This is where all email headers
> are downloaded again as if they were new! There are *Many* users here
> who would complain intensely if this happened and I was really wanting
> the migration to be as invisible as possible.
>
> Is there a way to do what I have described without the clients
> redownloading headers / full messages?
>
> I have been working on this for some time now but have hit a roadblock
> and don't know where to turn, any help would be really appreciated!
>
> Notes:
>
> * The proxy is not used during imapsync.
> * Some users have 20 years worth of mail running into 10's of GB
> * I have looked at dsync but the docs state that the mailbox should not
> be accessed during sync, this is not possible for me (it doesn't say why
> this is the case however)

Sounds like you have not adjusted the message UID to not change on the  
new server?

http://wiki2.dovecot.org/Migration

Regards

Andreas



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