em0 freezes on ZFS server

[Daniel Braniss]

> On Fri, 26 Feb 2010 13:31:38 +0100 Gerrit Kühn
> <gerrit at pmp.uni-hannover.de> wrote about Re: em0 freezes on ZFS server:
> 
> GK> JC> Note how close the "current" value is to that of "total".  I'm not
> GK> JC> too surprised you're seeing what you are as a result of this.
> GK> JC> What on earth is this machine doing at all times?
> 
> GK> Is there any way I could find out what is actually using these buffers?
> 
> Sorry for replying to my own email:
> At least in my case I found out what is eating the buffers: nfsd does!
> The buffers stop increasing as soon as I stop nfsd. However, they start
> increasing as soon as I start nfsd again.
> Are there any ideas how to fix this? Downgrading back to 7-stable is not
> really an easy task as far as I know, and I need the server to run without
> having to reboot it once for twice a day...

I want to add some spices to this stew: :-)
I have this big server (> 10 TB) which was running pretty much without major
problems, till one morning it started panicking because some 'ZFS * credential *',
Since this server is used by many and uptime being a priority,
I upgraded it to 8-stable, the panic went away, one problem solved.

Some few day later it hung, and it's now hanging every few days.
Most of the hangs are because there is no network, but the NIC is bce not em!
I doubled kern.ipc.nmbclusters and lets see what happens ...

netstat -m:
23066/6634/29700 mbufs in use (current/cache/total)
22072/5942/28014/51200 mbuf clusters in use (current/cache/total/max)
22021/2939 mbuf+clusters out of packet secondary zone in use (current/cache)

hope this helps in finding a cure,
	danny