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Re: [Linux-cluster] IMAP server clustering ...




But would you even need the GFS file system then ? Could each box just be accessing a reiserfs via the FC ? and let the application take care of the "locking" ?


Michael.



Lon Hohberger wrote:
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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-- Michael Gale Lan Administrator Utilitran Corp.

The best part is when the people who know the least are the ones ranting and raving.


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