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From "Jason Webb" ...@inovem.com>
Subject RE: IMAP Development Pointers
Date Thu, 04 Sep 2003 16:06:40 GMT
I shall have a think then (and set about doing it)
DJB's site has a good explanation on how maildir works 
http://qmail.plig.org/man/man5/maildir.html

-- Jason 


> -----Original Message-----
> From: Edward Flick [mailto:eddy@cdf-imaging.com] 
> Sent: 04 September 2003 15:24
> To: James Developers List
> Subject: RE: IMAP Development Pointers
> 
> 
> Yeah, maildirs seem pretty effective as a store.  Thats 
> actually what I was hinting at (with a link file instead of 
> real links as this is a java program and will be running on 
> platforms which don't support real links).  I don't buy into 
> the idea that creating multiple files will cause much more 
> disk thrashing, as a spool file can be scattered all of over 
> the drive too. Although, the open/close efficiency issue is 
> real, BUT I think this can be counteracted with a good 
> full-text index file.  Also, thanks to the newer journaling 
> file systems, it would be a lot easier to guarantee that a 
> message is uncorrupted.  Although, I definetely think the 
> indexing system should be implemented after a simple maildir 
> implementation is put into place. Anyways, this would just be 
> a step to at least get this into something close to a beta 
> phase.  What do you guys think?
> 
> -----Original Message-----
> From: Jason Webb [mailto:jw@inovem.com]
> Sent: Thursday, September 04, 2003 3:02 AM
> To: 'James Developers List'
> Subject: RE: IMAP Development Pointers
> 
> 
> If there is enough interest or need I will write a 
> maildir-style repository.  This is used by qmail and 
> Courier-IMAP to great effect and provides folders etc., and 
> it's safe(ish) over networked file systems. The current 
> repositories are less than ideal other than for folder based 
> storage ,particularly the mbox one ;)
> 
> -----Original Message-----
> From: Jim Wright [mailto:jimw@paneris.org]
> Sent: Wednesday, September 03, 2003 5:40 PM
> To: James Developers List
> Subject: Re: IMAP Development Pointers
> 
> 
> Hi Edward,
> 
> I have University of Washington IMAP on my Linux machine
> and use an experimental format mx which is as you describe.
> To quote the docs:
> 
> . mx    This is an experimental format, and may be removed in a future
>     release. ...
> 
>     [snip]
> 
>     mx is somewhat inefficient; the entire directory must be read
>     and each file stat()'d.  We found it intolerable for a
>     moderate sized mailbox (2000 messages) and have more or less
>     abandoned it.
> 
>     [snip]
> 
> 
>     There's a general reason why file/message formats are a bad idea.
>     Just about every filesystem in existance serializes file 
> creation and
>     deletions because these manipulate the free space map.  
> This turns out
>     to be an enormous problem when you start 
> creating/deleting more than a
>     few messages per second; you spend all your time thrashing in the
>     filesystem.
> 
>     It is also extremely slow to do a text search through a
>     file/message format mailbox.  All of those open()s and 
> close()s really
>     add up to major filesystem thrashing.
> 
> I was not completely convinced by this. File system devices 
> are getting faster for a start.
> 
> 
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