On Saturday 19 July 2003 08:03 pm, Jeremy C. Reed wrote:
> On Sat, 19 Jul 2003, Eric Lee Green wrote:
> > Because the only imap server that'll serve old-fashioned single-file mail
>
> Dovecot can also use mbox.
I'll need to investigate. Hoary old wu-imapd is as nasty as wu-ftpd ("free
root access for hackers since 1995!").
> > slows things to a crawl on the server it's running on. The other imap
> > servers out there require Maildir-format mail folders, which chew up
> > your inodes like crazy and thus aren't suitable for an ISP's mail
> > server.
>
> With big disks, I don't consider that a problem. For example, a common
> default is to have one inode for every 4096 bytes.
I have 75,000 EMAIL's in my imap directory, averaging about 2K apiece (yes, my
folder tree is quite impressive!). I'd need to format with double the inodes
to do maildir, and it'd slow everything else down tremendously -- for
example, have you ever run 'tar' on directories full of many small files? It
runs at snail's pace!
> What's your definition of an ISP's mail server? (How many users? How many
> messages?)
Well, one medium-sized ISP here in the Valley handles about 1 EMAIL per
second, or approximately 85,000 per day or around 150mb worth. Granted,
3/4ths of those probably get killed by SpamAssassin as spam :-}.
That's another issue -- disk usage. I currently have about 150 megabytes of
accumulated EMAIL in my imap folders. If I were an ISP, I would want those
EMAIL's off my mail server ASAP, and POP3 does that, IMAP doesn't.
> (By the way, I maintain a POP3 server project; it uses mbox, but one day I
> may code in maildir support too.)
I do like maildir, but it *is* expensive, resource-wise, in terms of both
inodes and in what it takes to backup the mail server. Other than ReiserFS,
most other filesystems out there just aren't very efficient at handling lots
of small files.
--
Eric Lee Green
mailto:eric@badtux.org
Unix/Linux/Storage Software Engineer needs job --
see
http://badtux.org for resume
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