Odd network issues on ZFS based NFS server

[Jeremy Chadwick]

On Thu, Jun 10, 2010 at 01:13:16PM +0200, Anders Nordby wrote:
> On Wed, Jun 09, 2010 at 11:28:52AM -0400, Rick Macklem wrote:
> > When you tried a different NIC, was a different type (ie. different
> > chipset that uses a different device driver)? I suggested that not
> > because I thought the hardware was broken but because I thought it
> > might be related to the network interface's device driver and switching
> > to a different device driver would isolate that possibility.
> 
> Nope. I switched from NIC 1 to 2, and switched server to an identical
> one. They both use bge NICs, a very common interface. I somehow doubt
> this is related to the NIC or driver, I have many machines with the same
> bge NIC (HP NC7782) that does not have any problems like this.

This may not be the problem of course, but are they they *exact* same
model and revision of NIC?  pciconf -lvc on both boxes, and looking for
the relevant bgeX interfaces, would determine that.

I believe Rick was recommending you switch to another model of NIC that
doesn't fall under the same driver, e.g. do you see this behaviour when
using em(4).

Also, can you provide uname -a output, or specifically the build date of
the kernel.  There have been bge(4) changes happening regularly
throughout the lifetime of RELENG_8, including into the -PRERELEASE
stage.

> Mem: 25M Active, 147M Inact, 1021M Wired, 112K Cache, 316M Buf, 1780M Free
> Swap: 6144M Total, 6144M Free
> 
> The server doesn't have many connections, 16 in ESTABLISHED state. As
> you can see from top, the server has 1780 MB free memory.

Clarification: I believe it actually has 1927MB (147M Inact + 1780M
Free) available.  I've always understood top's "Free" field to mean
"number/amount of pages which have never been touched/used since the
kernel was started", while "Inact" to mean "number/amount of pages which
have been touched/used but are not actively being used, this available
for use".

If someone more familiar with the VM and top could expand on this,
that'd be helpful.

-- 
| Jeremy Chadwick                                   jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |