LinkStation Pro Quad suitablity for use as a quorum disk device in a Red Hat High Availblity cluster

[ukoda]

I run servers for my self as a embedded systems developer and for my family.  I'm trying to increase the long term reliability by moving from a master/slave pair of Cent OS servers to a High Availability cluster of 4 servers.  For storage I was considering a pair of Link Station Pro Quad NAS.  They appear to be built on a good platform and have a reasonable price.  There is only mention of support for Windows and Apple clients.  Given the underlying OS on them is Linux I was hoping they would also support Linux.  NFS is often offered to do that but it looks like the "quorum disk device" I need is more specific than that.  To quote from the Red Hat's documentation:

 

A quorum disk device should be a shared block device with concurrent read/write access by all nodes in a cluster. The minimum size of the block device is 10 Megabytes. Examples of shared block devices that can be used by qdiskd are a multi-port SCSI RAID array, a Fibre Channel RAID SAN, or a RAID-configured iSCSI target.

 

My experience with block devices is they are locally mounted drives where as NAS unit present a higher level access.  Has anyone experience with working such a configuration?  Can this be done with a Link Station Pro Quad NAS or will have to build my own NAS from scratch?