[Dovecot] backing up maildir dovecot files

[Steffen Kaiser]

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On Mon, 11 Feb 2013, Reindl Harald wrote:

> Am 11.02.2013 22:37, schrieb Steve Litt:
>> On Mon, 11 Feb 2013 21:47:57 +0100
>> Reindl Harald <h.reindl at thelounge.net> wrote:
>>> Am 11.02.2013 21:34, schrieb David Mehler:
>>>> I'm having to migrate servers. Both are dovecot2 systems. I'm
>>>> wanting to copy over my mail store from one system to the other.
>>>> I'd like to preserve dates/times of emails. These are maildir
>>>> setups on both boxes, I'd like to be as transparent to the end user
>>>> as possible. I currently have the first dovecot system offline and
>>>> the second dovecot system is offline.
>>>
>>> assuming that BOTH servers are down as fro any other transfers
>>> like mysql-datadirs and any critical things which should go
>>> save and fast by preserve attributes:
>>>
>>> rsync --force --delete-after -tPrlHpogEAXz /folder/
>>> root at newserver:/folder/
>>>
>>> # -z compress
>>> # -t timestamps
>>> # -P progress
>>> # -r recursive
>>> # -l links
>>> # -H hard-links
>>> # -p permissions
>>> # -o owner
>>> # -g group
>>> # -E executability
>>> # -A acls
>>> # -X xtended attributes
>>
>> That's how I'd do it also. I think if you didn't mind including -D,
>> which from my understanding is --special and --devices, neither of
>> which I'd expect in a maildir, and if you wanted to do your deletion
>> manually after the fact, would this be equivalent?
>
> well, i have them ususally in my "rsync.sh" but did not expect
> such files in a maildir, but yes it does not hurt
>
>> rsync  -PaHAX /folder/
>>
>> The man page says -a (--archive) is equivalent to -rlptgoD, and you
>> have all but D listed up there.
>>
>> My thinking on later manually deleting the old maildir, instead of
>> letting rsync do it, is that if somehow, some weird thing goes wrong, I
>> have the old one for backup. Who knows, maybe I copied the thing on top
>> of the wrong other maildir and have to back it out -- I'd have the old
>> maildir as a reference of which files.
>
> you missunderstand "--delete-after"
>
> this is for delete files in the TARGET folder which is not
> or no longer in the source and IMHO very very important
> if you want sync folders 1:1 because old artefacts can have
> very bad effects
>
> without you merge folders and if i know "hey my source contains
> exactly what i need, not more and lot less" this is not what i
> would like and never did in 10 years IT

If you use "--delete-after" you could add "--fuzzy", which theoretically 
could save transfers because of filename renames.

Anyway: Any form of "--delete" is required for Maildir, IMHO, because 
Labels, Tags, Keywords (or whatever the MUA calls it) and status 
information (seen, read, deleted) are reflected by the filename. Hence, if 
one does not "--delete", the _same_ message might pop up in the Maildir 
multiple times but with different status and/or tags. Same applies to new 
messages, because they are storred in <maildir>/new and later moved to 
<maildir>/cur. So one ends with the same message in "new" and in "cur".

- -- 
Steffen Kaiser
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