On Mon, 4 Apr 2011, Chuck Swiger wrote:
On Apr 4, 2011, at 12:14 PM, Marc G. Fournier wrote:
OK-- Cyrus IMAP uses a variant of maildir, so you're relatively safe even if
locking is not available.
So, just to get this clear ...
If I were to boot a diskless station using an NFS backend, then that instance
would be prone to corruption since lockd wouldn't work, even though the only
processes handling the files on that mount?
If you're running a diskless system using NFS filesystem for storage,
and you run stuff that wants to do fcntl/lockf/flock locking, and
rpc.lockd isn't available, then yes, there is risk of data corruption.
However, Postfix can use .dotfile locking, even if fcntl (etc) locking
is broken, and maildir is designed to avoid needing locking the way mbox
does:
http://www.postfix.org/NFS_README.html
rpc.lockd provides locking at the filesystem level. Locks are performed
against file descriptors either for entire files or record-level
locking; they are not specific to a single process (indeed, locking
would be mostly useless if it was only visible within a single process).
Okay, next question ... if lockd is running, should fcntl locks work? My
read of the NFS_README.html above indicates to me that they should ... but
if that is the case, then it comes back to why doesn't it?
----
Marc G. Fournier Hub.Org Hosting Solutions S.A.
scra...@hub.org http://www.hub.org
Yahoo:yscrappy Skype: hub.org ICQ:7615664 MSN:scra...@hub.org
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