On Wed, Dec 23, 2009 at 10:17:57AM -0600, Kyle Wheeler wrote:
> Now, I'm assuming that you're storing your mbox locally on a standard 
> unix filesystem rather than on an NFS-mount or on an MS-DOS partition 
> or something similarly weird. 

Does mbox have issues on MS-DOS partitions?  I wasn't aware of any
(though you need to be careful about using mixed case).  I was aware
that maildir does, because on MS filesystems, you can't use ':' in a
path.

> And as long as you avoid those, you can be assured that using mbox
> is *safe*. It's not *efficient* (because everyone who touches the
> mbox must lock the file first), but it is safe.

I really hate when people say stuff like this.  It's true that you
have to lock the file before you *write* to it, but even for busy
mailboxes, the user will basically never notice this, unless maybe
he's still reading mail on a PDP-11 with a bunch of other people.
Plus, while maildir doesn't need to lock, it does need to open(2)
every individual message, whether you're reading or writing, which
more than makes up for not having to lock in terms of efficiency
lossage.  

Both folder formats are efficient at some things, and less efficient
at others.  Which one will perorm better for you depends a lot on your
usage patterns and the underlying filesystem.  Fans of maildir like to
sell it as being inherently better than mbox in every way, and that's
simply false.  I use both, about 50% each, because for my usage
patterns, maildir is better about half the time, and mbox is better
the other half.  [This is why the fact that Mutt behaves (or mostly
behaved) differently for the two formats has always been a pet peeve
of mine.]

I was about to write a blurb about how locking on NFS isn't really
*that* bad (anymore)... but yeah, it is. ;-)  In modern, homogenous
environments with well-behaved apps, odds of data loss are only
slightly worse than they would be if you took NFS out of the picture,
i.e. it's really only an issue in server failure modes, but that
tends to be when data loss occurs regardless of NFS... NFS + mbox
increases the odds of loss occuring only slightly (with well-behaved
apps), but makes the odds of the impact being serious much higher
(it's unlikely, but you might lose your entire mail folder).  Trouble
is, in practice there's no such thing as a modern, homogenous
environment, where all the apps are well-behaved! :)

-- 
Derek D. Martin    http://www.pizzashack.org/   GPG Key ID: 0xDFBEAD02
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