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Re: [Linux-cluster] Using GFS without a network?

On Mon, 2005-09-05 at 22:52 +0200, Andreas Brosche wrote:

> Long story cut short, we want
> - GFS on a shared SCSI disk (Performance is not important)

Using GFS on shared SCSI will work in *some* cases:

+ Shared SCSI RAID arrays with multiple buses work well.  Mid to high
end here, not JBODs with host-RAID controllers.  The biggest discernable
difference between one of these and a FC SAN array is the fact that it
has SCSI ports instead of fiber-channel ports.

? Host-RAID *might* work, but only if the JBODs behind it has multiple
buses, and the host controllers are all in "clustered" and/or "cache
disabled" mode.

- Multi-initator SCSI buses do not work with GFS in any meaningful way,
regardless of what the host controller is.

Ex: Two machines with different SCSI IDs on their initiator connected to
the same physical SCSI bus.

> - dlm without network access (theoretically possible...
>   but how dependant is GFS on the cluster services?)

The DLM runs over IP, as does the cluster manager.  Additionally, please
remember that GFS requires fencing, and that most fence-devices are

It may be possible to work around the need for actual ethernet by using
something like PPP over high speed serial, but I don't see how that's
better than a crossover ethernet cable.  Also, I don't know if it will
work ;)

Many users choose to separate cluster communication from other forms by
using a fully self-contained private network.

There is currently no way for GFS to use only a quorum disk for all the
lock information, and even if it could, performance would be abysmal.

-- Lon

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