[Linux-cluster] IMAP server clustering ...
Lon Hohberger
lhh at redhat.com
Thu Oct 28 22:06:39 UTC 2004
On Thu, 2004-10-28 at 13:14 -0600, Michael Gale wrote:
> 2. GFS does not protect against data corruption as it is the
> applications responsibility to making sure that data written to a file
> is complete.
> 3. Maildir format does not require file locking and works great over NFS
> except for the speed issue of course.
"Not requiring file locking" is not the same as "not requiring any
locking".
> If you use Courier IMAP every body can access the same directories /
> partitions at the same time because file locking is not an issue.
> "IMAP_USELOCKS
>
> This setting in /usr/lib/courier/etc/imapd must be enabled. This
> setting uses dot-lock files to synchronize updates to folder indexes
> between multiple IMAP clients that have the same folder opened.
> This setting is safe to use with NFS, as it does not use actual
> file locking calls, and does not require the services of the problematic
> NFS lock"
Instead of file locking, they're doing dot-locking.
I suspect GFS would work fine if you had the above setting enabled;
creating a file (e.g. a dot-lock) should be atomic across the cluster.
-- Lon
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