On 23.3.2012, at 19.11, Stan Hoeppner wrote:
I assume you do still have some minor locking/performance issues with the INBOX, even with Director, when LDA and the user MUA are both hitting the INBOX index and mbox files. You'll still see this with mdbox, but probably to a lesser degree if you use a smallish mdbox_rotate_size value. To mitigate this INBOX locking you could go with a dual namespaces, using maildir or sdbox for the INBOX and mdbox for the other user mail folders.
The biggest difference is that mbox requires read locks, mdbox doesn't. mdbox lock waits are very similar to maildir's. Of course, I don't know about the cluster filesystems' internal locking, but I thought it was even worse with Maildir than with mbox because it had to get a read lock for each read file, but I guess this depends on the filesystem.