[CentOS] Fwd: Bug 800181: NFSv4 on RHEL 6.3 over six times slower than 5.8

Tue Jul 17 12:48:40 UTC 2012
Les Mikesell <lesmikesell at gmail.com>

On Tue, Jul 17, 2012 at 4:33 AM, Johnny Hughes <johnny at centos.org> wrote:
>> I always wondered why the default for nfs was ever sync in the first
>> place.  Why shouldn't it be the same as local use of the filesystem?
>> The few things that care should be doing fsync's at the right places
>> anyway.
> Well, the reason would be that LOCAL operations happen at speeds that
> are massively smaller (by factors of hundreds or thousands of times)
> than do operations that take place via NFS on a normal network.

Everything _except_ moving a disk head around, which is the specific
operation we are talking about.

>  If you
> are doing something with your network connection to make it very low
> latency where the speeds rival local operations, then it would likely be
> fine to use the exact same settings as local operations.

What I mean is that nobody ever uses sync operations locally - writes
are always buffered unless the app does an fsync, and data will sit in
that buffer much longer that it does on the network.

   Les Mikesell
     lesmikesell at gmail.com