[kdepim-users] dimap, where are mails stored locally and how to back up?

Dirk Sarpe dsarpe at xs4all.nl
Wed Jan 4 11:51:27 GMT 2012


Hi Martin,

Thanks for the your answer. It seems that I need to rethink my current 
backup and synchronisation scheme a bit.

Martin Steigerwald wrote:
> Am Mittwoch, 4. Januar 2012 schrieb Dirk Sarpe:
>> It seems that all mails of all DIMAP accounts are in
>> /.local/share/akonadi/file_db_data/
>> What I find disturbing, there is no folder structure whatsoever in this
>> folder, just the plain files. How is one supposed to make a sensible
>> backup of this?
> 
> You need this directory *and* the akonadi database which has the
> information which mail is stored in which file. For searching you also
> need the Nepomuk index.

I was afraid of this. Makes also the migration from one client to another a 
bit ugly. And currently it does not seem to me that Akonadi is finding 
widespread acceptance in projects outside the KDE world. Importing mails 
from a directory structure was not a problem between clients (to be honest I 
only tested with thunderbird and kmail). I do not like the idea of having 
data tied to a specific application.
 
> I just rsync /home completely after having stopped Akonadi before. I am
> not using KDEPIM 2 yet, but I am quite sure that this should work. If you
> use a system-wide database, you better stop that one, too.
> 
> Another approach would be to mysqldump the database and rsync the
> file_db_data.
> 
> In case you do not want to stop Akonadi and database during the complete
> backup time you´d need some kind of snapshot to do this from so that
> database and files are in sync for the backup.

My experience with database backups is very limited at best, but thank you 
for the pointers. I will have a look at the different options. I guess a 
drawback of the db-stop; rsync; start-db method is that backups can not be 
very frequent (e.g. hourly). Not that I do this frequent backups at the 
moment.

> For own Nepomuk data like annotations, tags and such there is a backup
> utility including schedule settings under systemsettings / desktop search.
> All the data from the index files or mails can be rebuild and is not
> stored in that backup.

I was always wondering why the Nepomuk backup was so small, this explains 
it, thanks. Currently Nepomuk's indexing is halfway broken for me anyway, 
i.e. reindexing every new session and the search is not very reliable, but 
those are another problems.

> It would probably be good to have such a kind of backup for Akonadi as
> well to quicken recovery times on data loss.

I have only looked briefly at the master thesis of Zwerus (2007)[1], but in 
the conclusion there is the suggestion to implement a backup system for 
Akonadi before public release.

> That said all of this data should be rebuildable from the remote IMAP
> account in case of loss.

Let me just say, one of the IMAP servers I need to use for work is not the 
most reliable and no I do have zero influence on it. ;)

Thanks again,
Dirk


[1] http://doc.utwente.nl/64470/

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