[Dovecot] New mailbox format

[Marc Perkel]

dean gaudet wrote:

>On Fri, 23 Sep 2005, Todd Vierling wrote:
>
>  
>
>>On Fri, 23 Sep 2005, dean gaudet wrote:
>>
>>    
>>
>>>here's one point where my thinking has differed -- i'd treat the mailbox
>>>files as read-only (plus one file which is append-only) and include an
>>>append-only modification log for recovery purposes...  read-only mailbox
>>>files permit compression,
>>>      
>>>
>>Though they require sequential reading order for parsing, so think about
>>reading a bunch of messages from the end of the mbox:  one full
>>decompression for indexing, then very close to full decompression for every
>>message retrieval in the batch.  You'd think that retrieving a sequential
>>block via IMAP might help, but a lot of MUAs prefer single message random
>>access.
>>    
>>
>
>the amount of data per compressed file is completely tunable -- in my case 
>my cron job only compresses when the "current" mbox hits 16MiB.
>
>
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>>To address the situation you want, readonly archival, my vision would be a
>>compressed maildir (or equivalent), using each mail as a separately
>>compressed entry.  Zip is a pretty good format for this purpose.  Though
>>per-file compression is typically only about half as efficient as whole-mbox
>>compression, you'd have much faster search and retrieval if the file entries
>>had their own compression dictionaries.
>>    
>>
>
>so basically it's a classic tradeoff:  speed vs. space... if you design 
>with mbox instead of maildir then you get to decide where to set the 
>tradeoff... whereas if you use compressed maildir you've given up on space 
>immediately.  (and i'm not so convinced you get any speed, because i find 
>maildirs with 100000 entries to be a total dog.)
>
>-dean
>
>  
>
Just curious - have any of you tried the ReiserFS file system with 
Maildir? I would think that it should make maildir a lot faster and more 
efficient.

-- 
Marc Perkel - marc at perkel.com

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