[Dovecot] nfs director

[Timo Sirainen]

On Thu, 2010-09-02 at 09:47 -0400, Charles Marcus wrote:
> On 2010-09-02 9:08 AM, Cor Bosman <cor at xs4all.nl> wrote:
> > NFS has a problem where caching of the files
> > can cause each imap server to see outdated information. Server 1 could
> > have just written some updates into the index file, but Server 2 doesnt
> > see this yet, and writes conflicting data into the index file.
> 
> Just curious, but is there no way to just disable the caching on the NFS
> share where the indexes are stored?

Disabling attribute caching solves most of this, but increases the NFS
traffic by 10x or so (and still isn't perfect).

Dovecot v1.1 added a setting where it tried to flush the NFS cache only
when necessary. It worked better than nothing, but not perfectly. I
tried fixing it for a long time, spent a lot of time reading Linux and
FreeBSD NFS kernel code and writing test programs, trying to get Linux
to fix some things .. then I finally gave up.