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[OT] maildir (was Re: procmail and Large File Support)



can't help but chime in here :)

On Mon, Feb 28, 2005 at 09:22:30AM +1100, Brian May wrote:
> Not every situation warrants using maildir, it uses a large number of
> inodes, is slow to scan (yes, mbox isn't very good either),
> inefficient at storing large number of very small files (due to block
> size limitations of file system), and more complicated to
> transfer/move/share.

it does use a large number of inodes, but i've found that even on large
filesystems with many users, there's not a real risk of starving the fs
of inodes.  ymmv.  i'm not sure about the transferring/moving/sharing though.

figuring the average email is about 13-15k, i believe an ext2/ext3
filesystem created with default options would fill up before running
out of inodes.

> Of course, all of these factors depend on the file system used. I am
> confident somebody could point out a file-system that eliminates many
> of these disadvantages.

recent versions of kernel/ext2/ext3 have built-in dirent hashing, which
cuts heavily on the many-files penalty.  another benefit of maildir
is that when you modify a single message, you only need to modify the
individual file, as opposed to the entire mailbox.  in some of the
sloppier imap servers (*cough* uw-imap *cough* *cough*), this can cause
huge, grind-your-server-to-a-halt performance hits as deleting, or
merely reading a new message necessates a huge amount of i/o.


	sean


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