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

Tue Jul 17 13:27:24 UTC 2012
m.roth at 5-cent.us <m.roth at 5-cent.us>

Les Mikesell wrote:
> 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.

I would also think that, historically speaking, networks used to be
noisier, and more prone to dropping things on the floor (watch out for the
bitrot in the carpet, all those bits get into it, y'know...), and so it
was for reliability of data.
> 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.

But unless the system goes down, that data *will* get written. As I said
in what I think was my previous post on this subject, I do have concerns
about data security when it might be the o/p of a job that's been running
for days.