On 24/06/10 12:42, Iwao Shikase wrote: > In my environment, Database cluster is in NFS server. So you are mounting an nfs file system shared by "localhost" ? Why not run PostgreSQL directly on the underlying file system, rather than via nfs? > I guess that, In my environment, the mount options, system synchronously > and without cache does not need. I would still expect to lose some written data if the system crashed or lost power and nfs write caching was enabled. Because nfs's caching doesn't guarantee write ordering, this data loss would probably horribly corrupt your database. If you can get your NFS implementation to guarantee write ordering then it's quite safe to cache. Good luck proving that it's doing the right thing, though. Even if you're certain it's correct, you need to do a lot of testing where you abuse the server and see how it copes. Unplug it unexpectedly. Press the reset switch. 'kill -9' the backends. Crash the operating system. Etc. See if there's any sign of damage to the PostgreSQL storage after repeated abuse of the server like that. > If I mount the database cluster with caching in my environment, What kind of > problem I will meet? Please give the information about the problem you met. It varies so much by NFS implementation and version that it is really hard to say. Personally, I would never, EVER run a database of any kind over nfs, but perhaps I'm just scarred by Linux's NFS implementation. -- Craig Ringer Tech-related writing: http://soapyfrogs.blogspot.com/ -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
