I am running sqwebmail-2.1.1 on a cluster of mail servers which have
user home dirs nfs mounted off a Netapp F720 filer. There are four
servers load balanced by a ServerIron in round-robin. Everything
works fine except when a user deletes messages from any of their
folders, that information never gets updated in their sqwebmail-curcache.db2
file. Messages get deleted properly but the cache file still shows them
existing.
I have tried a different configuration using only one server running
apache with the same home dirs nfs mounted. Same problem. Documentation
on the Netapp appliance states that file locking is advisory when locking
is requested from Unix clients. I have tried mounting the home directories
with the "nolock" nfs option with no improvement in the problem.
If I delete the *.db2 files, there is no problem creating new ones which
will then contain the correct snapshot of the user's folders and messages.
But after that, the cache file never gets updated with new information.
The only thing I can imagine that might cause this is if one process has
a shared (read) lock on the .*db2, and the nature of advisory locking
requires that a different process wishing to set an exclusive write lock
(which would be required to update the file) to check for existing locks
on the file, and finding the shared lock, would be unable to do so.
But as I mentioned earlier, home is now mounted using "nolock", so
I'm not sure how this could be an nfs issue.
Has anyone else experienced a similar problem, or is there some bug or
posting in the archives somewhere that you could point me to ? Could
this be something specific to the version I'm running, and might upgrading
be the solution? Are there any known issues using sqwebmail in a load-
balanced configuration such as this or any known problems with nfs ?
Thanks in advance for any advice/suggestions.
K. Bradford
