Re: [BackupPC-users] backuppc related: mailbox of choice

[Carl W. S. <ch...@re...>]

On 10/20 06:32 , Rich Duzenbury wrote:
> > I've never seen a 'corruption' issue with mbox files. (and I administrate a
> > fair number of mailservers, and have done so for several years).
> I have.  Just have a user expunging email at the same time the system is
> trying to deliver messages to the same file.  If the locking is not
> exactly correct, *poof* goes at least some of the mbox.

ok. for better or for worse, Unix has 'cooperative locking'... you're free
to change files out from underneath other programs. 
I'm inclined to say this is something of an application issue... the
application should detect the file change before clobbering the old file,
and alert the user/merge the files; but I can see how a race condition is still there.

> > If you're me, and using mutt on the mailserver itself, and keeping your
> > mailboxes comparatively small (keep a backup copy of all your mail in one
> > box, which is rotated out regularly, then delete mail freely from the other
> > mailboxes); the time spent loading and unloading mailboxes when switching
> > between them, is the most painful part of the mail-reading experience.
> Huh?  I'm using evolution to access my maildirs on my local machine, and
> I don't seem to spend any perceptible time "loading and unloading
> mailboxes", other than the few seconds to start the mail client.  

exactly, you're using Evolution, which loads all your mailboxes
simultaneously. I use mutt, which only loads one at a time. (but takes much
less memory and runs far faster for most of the operations I do). so if I
want to look at another mailbox, it unloads one and loads the other.

it should also be noted that whatever you're using for your desktop system
is probably notably faster than the dual-500 Xeon that I read my mail on.
(especially since yours isn't a very active mailserver with hundreds of
users.) So you don't see the performance hit as badly as I do.

> Why
> bother to switch mail boxes all the time?  

for reading the mail that's been filtered off into them with procmail. :)

> Why bother with having to
> rotate mailboxes around?  

so they don't run the mailserver out of space. I'm only rotating out my
archives, which are a copy of all the mail I ever recieve (modulo some
spam). Once they get to 80+MB and 10K messages (about a month's worth),
they're onerously slow to load. (especially since I'm fighting other users
for disk bandwidth).

> This speaks to the kludginess of mbox.  I
> don't have to make such machinations with maildir.

no, it would be the same no matter what format they were in. Only slower
with maildir. (feels like it takes half-again as long to load a maildir
folder).

> > Mbox also makes it far easier for me to grab an entire mailbox, and rename
> > it, move it, search it, whatever.
> I'm not sure I agree.  I can rename a directory just about as easily as
> you can rename a file.  

yeah, but copying it across the network would be substantially slower, and
like you point out elsewhere, would require a packing into a tarball to
compress it all.

> For searching, I think mairix is far superior to scanning mbox
> files.  

you might have a point there. I don't search my old messages often enough to
worry about it much tho; and when I do search them, I'm often just looking
for one line.

> I can also pick out one or a few messages from a very large
> maildir, which would seem to be more of a problem with mbox.

grepmail is a good tool for that.

> This is true.  However, disk is so cheap now - buy another hard drive. 

sometimes that's an option; sometimes it isn't. :(

> In the case of mbox, you will have ten copies of the file in the
> pool if you have ten backups (assuming you get mail every day).

yep. this is the big advantage of it.

Now just build a system that works like maildir, but for syslog files,
without murdering performance. ;) it would definitely have advantages (for
BackupPC and other tools), and on low-activity systems might work reasonably
well... on anything big it would be horrifically disk-intensive tho.


> Final thought: even mbox is *way* better than the outlook 'lock the mail
> spool' nonsense.  

no argument here.


-- 
Carl Soderstrom

Do You Want "Tax and Spend" Kerry or "Borrow and Spend" Bush?
Vote Badnarik for President - The Only Real Choice
for Smaller Government  www.Badnarik.org
Vote Libertarian - Restore the American Dream