[Linux-cluster] RE: < fecing with out any hardware? >

Bowie Bailey Bowie_Bailey at BUC.com
Mon May 1 20:15:43 UTC 2006

Pool Lee, Mr <14117614 at sun.ac.za> wrote:
> What about software fencing? Is it really nesasary to be hardware!
> Is there a difference between lutre/cfs, the product that sun uses,
> and gfs? 
> I'm planning to do mostly numerical work with the cluster and thus I
> would like all the machines to be able to retrieve data, as if it
> was local on the machine. NFS is very limited in this regard because
> we intend on using vast arrays of matrices, that can be up to 1-2
> Gig.  
> I was hoping to implement GFS since all the machines are already
> setup, without the hardware fencing though. 

The thing with fencing is that you have to choose a method which is
supported by your configuration.  These are the basic ways to fence a

Manual fencing - nothing special needed, but it doesn't work well in a
production environment.

Power fencing - Forcibly reboots a misbehaving node.  Requires a
compatible power switch.

Network fencing - Blocks the misbehaving node's access to the cluster
resources.  Requires a compatible switch (usually used with fiber

Software fencing - Notifies storage management software to block
access to the misbehaving node.  Requires compatible storage
configuration.  I believe this is only supported with GNBD storage

Your choices are limited by your configuration.  The only options that
can be used with any configuration are manual and power.

I don't know about the differences between the RedHat Clustering and
lutre/cfs.  I DO know that any type of clustering will require fencing
of some sort.


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