[CentOS] NFS help

[Matt Garman]

On Mon, Oct 24, 2016 at 2:42 PM, Larry Martell <larry.martell at gmail.com> wrote:
>> At any rate, what I was looking at was seeing if there was any way to
>> simplify this process, and cut NFS out of the picture.  If you need
>> only to push these files around, what about rsync?
>
> It's not just moving files around. The files are read, and their
> contents are loaded into a MySQL database.

On what server does the MySQL database live?


> This site is not in any way connected to the internet, and you cannot
> bring in any computers, phones, or media of any kind. There is a
> process to get machines or files in, but it is onerous and time
> consuming. This system was set up and configured off site and then
> brought on site.

But clearly you have a means to log in to both the C6 and C7 servers,
right?  Otherwise, how would be able to see these errors, check
top/sar/free/iostat/etc?

And if you are logging in to both of these boxes, I assume you are
doing so via ssh?

Or are you actually physically sitting in front of these machines?

If you have ssh access to these machines, then you can trivially copy
files to/from them.  If ssh is installed and working, then scp should
also be installed and working.  Even if you don't have scp, you can
use tar over ssh to the same effect.  It's ugly, but doable, and there
are examples online for how to do it.

Also: you made a couple comments about these machines, it looks like
the C7 box (FTP server + NFS server) is running bare metal (i.e. not a
virtual machine).  The C6 instance (NFS client) is virtualized.  What
host is the C6 instance?

Is the C6 instance running under the C7 instance?  I.e., are both
machines on the same physical hardware?  If that is true, then your
"network" (at least the one between C7 and C6) is basically virtual,
and to have issues like this on the same physical box is certainly
indicative of a mis-configuration.


> To run the script on the C7 NFS server instead of the C6 NFS client
> many python libs will have to installed. I do have someone off site
> working on setting up a local yum repo with what I need, and then we
> are going to see if we can zip and email the repo and get it on site.
> But none of us are sys admins and we don't really know what we're
> doing so we may not succeed and it may take longer then I will be here
> in Japan (I am scheduled to leave Saturday).

Right, but my point is you can write your own custom script(s) to copy
files from C7 to C6 (based on rsync or ssh), do the processing on C6
(DB loading, whatever other processing), then move back to C7 if
necessary.  You said yourself you are a programmer not a sysadmin, so
change the nature of the problem from a sysadmin problem to a
programming problem.

I'm certain I'm missing something, but the fundamental architecture
doesn't make sense to me given what I understand of the process flow.

Were you able to run some basic network testing tools between the C6
and C7 machines?  I'm interested specifically in netperf, which does
round trip packet testing, both TCP and UDP.  I would look for packet
drops with UDP, and/or major performance outliers with TCP, and/or any
kind of timeouts with either protocol.

How is name resolution working on both machines?  Do you address
machines by hostname (e.g., "my_c6_server"), or explicitly by IP
address?  Are you using DNS or are the IPs hard-coded in /etc/hosts?

To me it still "smells" like a networking issue...

-Matt