CentOS - Jun 2007 - centos 5 GFS/Cluster - configure fence using NIC?

How does one configure a fence device in the form of a NIC card in 
centos 5?  Is the gnbd item relevant to this?

I have posted the question to linux-cluster also, but they are much less 
active overall, -so if you have info, massively appreciated...

-karl

Karl R. Balsmeier wrote:
> How does one configure a fence device in the form of a NIC card in 
> centos 5?  Is the gnbd item relevant to this?
I'm not sure what 'a fence device in the form of a NIC card' is.  
the
fence devices I'm familiar with include SCSI fence switches, 
fiberchannel SAN switches, and APC SmartPlug power switches.

in my test cluster, I used a Qlogic SANbox fiber switch to connect the 
cluster nodes to the shared storage.    the fencing was done by sending 
the Qlogic the commands to enable/disable the ports of the two nodes so 
only the active node could access the shared storage.

I suppose an Ethernet analog in an ISCSI SAN environment would be to 
send commands to a layer-2 or layer-3 managed switch to manipulate the 
VLANs to disable the standby nodes from accessing the ISCSI target 
device.   These systems would need separate dedicated NICs for LAN 
connectivity and cluster heartbeats.