em0 freezes on ZFS server

[Jeremy Chadwick]

On Fri, Feb 26, 2010 at 10:34:41AM +0100, Willem Jan Withagen wrote:
> This is wat netstat -m told me when it refused to revive em0:

Below are the netstat -m counters/lines of concern:

> 24980/2087/27067 mbufs in use (current/cache/total)
> 24530/1070/25600/25600 mbuf clusters in use (current/cache/total/max)
> 55305K/2801K/58106K bytes allocated to network (current/cache/total)

Note how close the "current" value is to that of "total".  I'm not too
surprised you're seeing what you are as a result of this.  What on earth
is this machine doing at all times?

Comparatively, here's some of our servers' netstat -m stats.  All these
boxes do nightly backups to a centralised box on a private gigE network.
All boxes use em(4).

RELENG_7 amd64 2010/01/09 -- primary HTTP, pri DNS, SSH server + ZFS

	514/1931/2445 mbufs in use (current/cache/total)
	512/540/1052/25600 mbuf clusters in use (current/cache/total/max)
	1152K/6394K/7547K bytes allocated to network (current/cache/total)

RELENG_7 amd64 2010/01/11 -- secondary DNS, MySQL, dev box + ZFS

	514/1151/1665 mbufs in use (current/cache/total)
	512/504/1016/25600 mbuf clusters in use (current/cache/total/max)
	1152K/2203K/3356K bytes allocated to network (current/cache/total)

RELENG_7 i386 2008/04/19 -- secondary HTTP, SSH server, heavy memory I/O

	531/624/1155 mbufs in use (current/cache/total)
	512/552/1064/25600 mbuf clusters in use (current/cache/total/max)
	1156K/2408K/3564K bytes allocated to network (current/cache/total)

RELENG_8 amd64 2010/02/02 -- central backups + NFS+ZFS-based filer

	1572/3423/4995 mbufs in use (current/cache/total)
	1563/3065/4628/25600 mbuf clusters in use (current/cache/total/max)
	3519K/7401K/10920K bytes allocated to network (current/cache/total)

-- 
| 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 |