Migrating IMAP (nnimap) servers?

Migrating IMAP (nnimap) servers?

[Bruce Stephens]

Suppose I read email using foreign nnimap groups to some server, and
that I know the server's going to be changed.  What can I do about
that in order to improve my chances of not losing stuff?  (Let's
suppose that if the administrators offer to move existing email, that
they can accurately move IMAP tags and things.)  

The manual covers changing nntp servers, but I don't see any similar
advice on moving IMAP servers.  Is that because gnus doesn't really
cache much, so it all just works?

(I guess one thing I'll do regardless is make copies of email in nnml
folders, just in case.)

Re: Migrating IMAP (nnimap) servers?

[Bruno Hertz]

Bruce Stephens <bruce+usenet@cenderis.demon.co.uk> writes:

> Suppose I read email using foreign nnimap groups to some server, and
> that I know the server's going to be changed.  What can I do about
> that in order to improve my chances of not losing stuff?  (Let's
> suppose that if the administrators offer to move existing email, that
> they can accurately move IMAP tags and things.)  
>
> The manual covers changing nntp servers, but I don't see any similar
> advice on moving IMAP servers.  Is that because gnus doesn't really
> cache much, so it all just works?
>
> (I guess one thing I'll do regardless is make copies of email in nnml
> folders, just in case.)

I'm not totally sure, so additional comments are welcome, but afaik all
the marks Gnus maintains locally for news are stored as imap flags on
the server, like read, seen, ticked and even dormant (might depend on
your Gnus version, though). So just switching servers should go alright
without further actions in this regard, if the flags are migrated, too.

What I'm not sure about is what to do with possibly cached articles.
Maybe somebody else can tell more?

Regards, Bruno.

Re: Migrating IMAP (nnimap) servers?

[Bruce Stephens]

"Bruno Hertz" <spammer.go.home@gmail.com> writes:

[...]

> I'm not totally sure, so additional comments are welcome, but afaik
> all the marks Gnus maintains locally for news are stored as imap
> flags on the server, like read, seen, ticked and even dormant (might
> depend on your Gnus version, though). So just switching servers
> should go alright without further actions in this regard, if the
> flags are migrated, too.

That sounds hopeful.

> What I'm not sure about is what to do with possibly cached articles.
> Maybe somebody else can tell more?

I've not used those (with imap, anyway).  I'd guess that there'd be an
issue with those---presumably it uses some kind of numbering, and
presumably that's the server-specific article number.

Re: Migrating IMAP (nnimap) servers?

[Bruno Hertz]

Bruce Stephens <bruce+usenet@cenderis.demon.co.uk> writes:

> "Bruno Hertz" <spammer.go.home@gmail.com> writes:
>
> [...]
>
>> I'm not totally sure, so additional comments are welcome, but afaik
>> all the marks Gnus maintains locally for news are stored as imap
>> flags on the server, like read, seen, ticked and even dormant (might
>> depend on your Gnus version, though). So just switching servers
>> should go alright without further actions in this regard, if the
>> flags are migrated, too.
>
> That sounds hopeful.
>
>> What I'm not sure about is what to do with possibly cached articles.
>> Maybe somebody else can tell more?
>
> I've not used those (with imap, anyway).  I'd guess that there'd be an
> issue with those---presumably it uses some kind of numbering, and
> presumably that's the server-specific article number.

Actually, thinking about it, you don't even need to 'switch', since your
mail servers are (presumably) part of your secondary select methods.

I.e. you could just add the new server there, subscribe to your folders
when it's online and see what it gives. If the old server is down by then,
Gnus will put it offline anyway, and you could remove it from your
secondary selects then or maybe even kill the subscribed folders one
by one and then kill resp. remove the server. So yes, I'm pretty sure
it should be no problem, especially when the migration is done
properly on the server side.

Finally, if you're concerned about loosing mail on the server side,
you could pull it before migration yourself to either maildir format
(fetchmail, procmail - don't know what happens with the flags in this
case though) or even to another imap server of your choice (mailutil
from uw-mailutils).

Regards, Bruno.

Re: Migrating IMAP (nnimap) servers?

[Bruce Stephens]

"Bruno Hertz" <spammer.go.home@gmail.com> writes:

[...]

> Actually, thinking about it, you don't even need to 'switch', since
> your mail servers are (presumably) part of your secondary select
> methods.

Yeah, I came to much the same conclusion (especially since the old
server isn't going anywhere soon).  So, it was much simpler than I
feared it might be: I just added the new server, and subscribed to the
relevant mail folders.

[...]

Re: Migrating IMAP (nnimap) servers?

[Bruno Hertz]

Bruce Stephens <bruce+usenet@cenderis.demon.co.uk> writes:

> "Bruno Hertz" <spammer.go.home@gmail.com> writes:
>
> [...]
>
>> Actually, thinking about it, you don't even need to 'switch', since
>> your mail servers are (presumably) part of your secondary select
>> methods.
>
> Yeah, I came to much the same conclusion (especially since the old
> server isn't going anywhere soon).  So, it was much simpler than I
> feared it might be: I just added the new server, and subscribed to the
> relevant mail folders.
>
> [...]


Great. Good to hear that things went smoothly :)