http://dovecot.org/tools/nfstest.c
I wrote a test utility that tests different ways to flush NFS attribute cache and data cache. Please test in your NFS setup and show me the results, so I can make Dovecot v1.1 works well with NFS.
Run the test several times (3 should be enough) to make sure the output stays the same, because the attribute cache flushes might incorrectly say "OK". And of course attribute cache must not be disabled for this test to work.
If you have other ideas how to flush either cache please tell me and I'll update the test utility. I'd like to have a way to flush the cache without having the NFS client send anything to server. Unfortunately all of the below ways do that.
Results for Linux v2.6.15 and v2.6.18:
Info: Testing attribute cache.. Info: Attr cache flush fchown(-1, -1): failed Info: Attr cache flush fchown(uid, gid): OK Info: Attr cache flush fchmod(mode): OK Info: Attr cache flush chown(-1, -1): failed Info: Attr cache flush chown(uid, gid): OK Info: Attr cache flush chmod(mode): OK Info: Testing data cache.. Info: data cache: Appends weren't noticed (ret = 0) Info: - Attribute cache flush helped Info: data cache (no caching): failed Info: data cache (attr cache): failed Info: data cache (lockf()): OK Info: data cache (flock(shared)): OK Info: data cache (flock(exclusive)): OK