akonadi/KDE PIM backup/restore

Martin Steigerwald martin at lichtvoll.de
Fri Oct 14 21:38:08 BST 2016

Am Freitag, 14. Oktober 2016, 10:20:01 CEST schrieb René J.V. Bertin:
> On Friday October 14 2016 08:36:56 Daniel Vrátil wrote:
> >I would argue that except for the search index, you want to preserve
> >everything (including the massive file_db_data), see below.
> That's OK.
> file_db_data is massive indeed, though for me more in number of files (over
> 5000) than bytes-on-disk (59Mb with ZFS lz4 compression which works nicely
> on text).
> Still, would you incur a big performance penalty using libzip or some such
> (leveldb?) to store all those files in an indexed, compressed archive. A
> massive directory containing (tens of) thousands of files isn't exactly
> efficient (and probably even more massive in terms of actual disk (sector)
> usage). I should probably spin this off to a separate thread.

Actually I don´t get some of the sizes in my setups.

Private mail account with more than 2000000 mails:

[…]~/.local/share/akonadi> LANG=C du -sch db_data file_db_data search_db
3.7G    db_data
176M    file_db_data
3.6G    search_db
7.5G    total

[…]~/.local/share/akonadi> find file_db_data -type f | wc -l

Exchange IMAP work account with fewer mails than the private one:

[…]~/.local/share/akonadi> LANG=C du -sch db_data file_db_data search_db 
8,7G    db_data
3,6G    file_db_data
1,3G    search_db
14G     total

[…]~/.local/share/akonadi> find file_db_data -type f | wc -l

[…]~/.local/share> du -sh local-mail 
24G     local-mail
[…]~/.local/share> find local-mail -type f | wc -l

Yes, this is no joke :)

14 GiB in total for managing *metadata* for my IMAP account. *Seriously*? 
Thats easily half a size or more of the whole account. Exchange reports I 
think 27 GB for the account, but I don´t really believe it. And yes, I have 
run a akonadictl fsck ; akonadictl vacuum on it recently.

And search_db may not even complete, as I nuked it after it filled my /home. I 
even touched a file "search_db" to avoid Akonadi Search recreating it, but it 
seems it nuked my file. So one bet is: Akonadi Search tries to build search db 
again and thus Akonadi receives all the mails through IMAP and *caches* then. 
Can we have Akonadi *not* cache any mails that Akonadi Search requests – it is 
utterly pointless to cache them? And I really would like to tell Akonadi how 
long it should retain items in cache and I would tell it: Forget after 2 weeks 
already. Exchange IMAP is bad, but not that bad that I need a local copy of 
everything (especially when not telling it to do disconnected IMAP).


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