* Heikki Linnakangas (hlinnakangas@xxxxxxxxxx) wrote: > On 05/27/2014 02:06 PM, Albe Laurenz wrote: > >I just learned that NFS does not use a file system cache on the client side. > > > >On the other hand, PostgreSQL relies on the file system cache for performance, > >because beyond a certain amount of shared_buffers performance will suffer. > > > >Together these things seem to indicate that you cannot get good performance > >with a large database over NFS since you can leverage memory speed. > > > >Now I wonder if there are any remedies (CacheFS?) and what experiences > >people have made with the performance of large databases over NFS. > > I have no personal experience with NFS, but sounds like a > higher-than-usual shared_buffers value would be good. It would certainly be worthwhile to test it. In the end you would, hopefully, end up with a situation where you're maximizing RAM usage- the NFS server is certainly caching in *its* filesystem cache, while on the PG server you're getting the benefit of shared_buffers without the drawback of double-buffering (since you couldn't ever use the NFS server's memory for shared_buffers anyway). All that said, there has always been a recommendation of caution around using NFS as a backing store for PG, or any RDBMS.. Thanks, Stephen
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