[Dovecot] Re: mailbox corruption
Kelly Sauke wrote:
Wietse Venema wrote:
Yannick Majoros:
What else is accessing the mailbox files? Any scripts running around that access mail without proper file locking, like scripts that replicate mail to another box?
Whay file system is being used?
If you can't figure out which is broken, then you'll have to use maildir files.
No scripts. If amavisd-new is safe, then nothing else should access mailboxes. Only via dovecot POP3/IMAP. Do you think it is worth to go
amavisd-new accesses mailboxe files, and what file locking mechanism would that be using?
Wietse
For what its worth, I'm seeing the exact same corruption as Yannick is talking about and the only two pieces of software installed on my machine are postfix and dovecot. One of those two is the culprit, not sure which one.
Yep, I would think the same. This is not an evidence, but a strong doubt: the same problem is still present after replacing MailScanner by amavisd-new. It could be that it happens less often, although, but I need some time to make real stats...
--
Yannick Majoros http://www.inma.ucl.ac.be/~majoros Informaticien AUTO-INMA/FSA/UCL
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At 11:03 AM 9/14/2005, Yannick Majoros wrote:
Kelly Sauke wrote:
Wietse Venema wrote:
amavisd-new accesses mailboxe files, and what file locking mechanism would that be using?
WietseFor what its worth, I'm seeing the exact same corruption as Yannick is talking about and the only two pieces of software installed on my machine are postfix and dovecot. One of those two is the culprit, not sure which one. Yep, I would think the same. This is not an evidence, but a strong doubt: the same problem is still present after replacing MailScanner by amavisd-new. It could be that it happens less often, although, but I need some time to make real stats...
Neither amavisd-new nor mailscanner access user mail storage; postfix does the final delivery. Don't let the content filter issue distract you from the real problem.
It might be worthwhile to try switching both dovecot and postfix to one of the other available locking schemes, but I don't know if that will help any.
-- Noel Jones
On Wed, Sep 14, 2005 at 12:42:44PM -0500, Noel Jones wrote:
It might be worthwhile to try switching both dovecot and postfix to one of the other available locking schemes, but I don't know if that will help any.
Locking of mailboxes is easy for delivery agents, they just append. POP/IMAP servers need to be able to modify (delete, add flags, ...) messages in the middle of the mbox file. Doing so robustly requires more than just locking, in order to not lose messages, the updates need to be atomic.
This is why "popper" (now known as "qpopper") on which I collaborated in the late 80s, makes a copy of the mbox file while it is working on it, and the final update is a rename() (atomic).
People who use quotas are unhappy about this, and perhaps the copying no longer happens (likely no longer robust also).
The appropriate robust combinations are:
- mbox, with copy for modify and file *size* limits,
not quotas, so a user can exceed the limit by 100% while
a mailbox is being modified.OR
- maildir, with filesystem quotas.However well other combinations may or may not work in typical practice, they fail in theory, and that is good enough for me.
-- Viktor.
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participants (3)
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Noel Jones
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Victor Duchovni
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Yannick Majoros