Cyrus IMAP and MySQL mailboxes (Building load-balancing cluster)

[Wesley Craig]

On 22 Nov 2006, at 19:10, Sarah Walters wrote:
> Only a single machine can have write privileges to the mailboxes  
> database at a time.

Actually, only a single process can be writing to a mailboxes  
database at a time.

> Then, assuming the database is closed between changes (can a  
> developer please confirm whether it is kept open by master or not?)  
> you should be able to run multiple IMAP servers over the same  
> filesystem stored on a NAS (network-attached storage, as opposed to  
> SAN).

I'm not sure why closing the database between changes might be  
important.  Multiple imapd processes on backends all access the same  
mailboxes database.  Writes are serialized with locks.  If a network  
filesystem implements these locks correctly, there's no reason why  
you couldn't run multiple "backends" against a single redundant  
filesystem.  There are a number of examples of people doing this.

:wes