On Dec 18, 2009, at 4:42 PM, Brandon Davidson wrote: > The Wiki article on NFS states that 1.1 and newer will flush attribute > caches if necessary with mail_nfs_storage=yes. We're running 1.2.8 with > that set, as well as mail_nfs_index=yes, mmap_disable=yes and > fsync_disable=no. We have a pool of POP/IMAP and SMTP machines that are > accessing the maildirs, and can't guarantee any sort of user session > affinity to a particular host. > > We also mount our NFS shares with 'noac', which is what I'm writing to > ask about. I'd like to stop doing that for performance reasons. Do you > see any issues with taking that out of the mount options, given our > environment?
Dovecot's NFS cache flushing doesn't work perfectly. But I think some/most/all of those conditions exist also when attribute cache is disabled. Or maybe not. I can't really remember anymore what I read in the kernel code :) And that was only for Linux and FreeBSD, don't know about other OSes. The issue was about directory entry caching, I don't remember if attribute cache also disabled it. Anyway.. I think you should just try enabling attribute cache and if things start breaking more, disable it again.
