[CentOS] extremely slow NFS performance under 6.x [SOLVED]

Mon Nov 4 18:35:39 UTC 2013
Les Mikesell <lesmikesell at gmail.com>

On Mon, Nov 4, 2013 at 12:26 PM,  <m.roth at 5-cent.us> wrote:
>> I'm trying to make sense of that timing.   Does that mean that
>> pre-6.x, fsync() didn't really wait for the data to be written to
>> disk, or does it somehow take 7 minutes to get 100M onto your disk in
>> the right order?   Or is this an artifact of a specific raid
>> controller and what you have to do to flush its cache?
> No, this is regardless of what box, old Penguins, newer Dell's with  PERC
> 600 or 700 RAID controllers. Apparently, this "barrier" controls
> journalling transactions, so that they are in order, or something like
> that.

I just don't see where that kind of time can go unless it is forcing a
flush of a large (and probably mostly unrelated) cache to disk -
possibly even in the internal drive caches if there is a way to do
that, and waiting for it to complete after each file close.

  Les Mikesell
    lesmikesell at gmail.com