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From "Edward Flick" <e...@cdf-imaging.com>
Subject RE: IMAP Development Pointers
Date Thu, 04 Sep 2003 14:24:13 GMT
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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