dovecot - Jul 2005 - Well, "Hard filesystem quota can also be problematic"

"Hard filesystem quota can also be problematic", quoth
<http://www.dovecot.org/>.

Since we actually use quota for our userbasg, this merited further
investigation.

Using 1.0-stable, we enabled quota on /var and /users filesystems, and set 
very low quota for a test account.  Then we had some mail delivered on it, and 
we moved some messages about.

At some point, Thunderbird started to croak about

	"The current command did not succeed.  The mail server responded:
	 Internal error occured.  Refer to server log for more information.
	 [<timestamp>].",
	"The current command did not succeed.  The mail server responded: .",
	"The current command did not succeed.  The mail server responded:
	 Out of disk space."

This I can live with.  Hoever, at some point in our experiments we also found 
that a mailbox (mbox format) that did contain a few dozen messages suddenly 
was truncated to 0 bytes.  Not so hot.

Can anyone tell me whether or not there is, or will be, some way of using 
dovecot on a system with quota without risk of data loss when quota limits are 
reached?  How do people cope with this?


Regards, Jeroen.

p.s. That first error message gave rise to the enclosed patch.
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Jeroen Scheerder wrote:
> "Hard filesystem quota can also be problematic", quoth 
> <http://www.dovecot.org/>.
[...]
> Can anyone tell me whether or not there is, or will be, some way of 
> using dovecot on a system with quota without risk of data loss when 
> quota limits are reached?  How do people cope with this?
[...]

Nobody uses quota on their servers anymore these days, I presume? :-)

Jeroen Scheerder wrote:
> 
> Can anyone tell me whether or not there is, or will be, some way of 
> using dovecot on a system with quota without risk of data loss when 
> quota limits are reached?  How do people cope with this?
> 
I use Dovecot 0.9.14 with disk quotas.

I use maildir format however.  you can't expect to use mbox format and 
not get data loss/corruption when you hit a filesystem quota.  I've 
fairly certain that even UW-IMAP will corrupt your mbox files in the 
case of exceeding your quota as well.

so, with the maildir storage format, procmail and mimedefang rules to 
reject mail for users that are over-quota, and dovecot configured to 
store indexes and control files on a non-quota'd filesystem, I've got a 
successful installation with filesystem quotas.

alan

On Wed, 2005-07-27 at 08:12 +0200, Jeroen Scheerder
wrote:
> 	"The current command did not succeed.  The mail server responded:
> 	 Out of disk space."
> 
> This I can live with.  Hoever, at some point in our experiments we also
found
> that a mailbox (mbox format) that did contain a few dozen messages suddenly
> was truncated to 0 bytes.  Not so hot.
This shouldn't happen. There is really only one place where mbox file is
truncated in the code, and it shouldn't be done unless client was
actually expunging messages. If you can reproduce it with strace output
I'd like to see that (set mail_executable = strace -o
log .../dovecot/imap).
> p.s. That first error message gave rise to the enclosed patch.
Thanks. I must have been writing occurred wrong forever :)

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