A more HW-oriented view of the NGAS Cluster is shown in this slide. It is probably the structure, which will be used in the near future for the Garching NGAS Cluster. Now a combination of the two concepts above is used.
	The cluster has one entry point as such. However, two Main Nodes are available for higher availability and for better performance. The client APIs can multiplex between the Main Nodes.
	The data server nodes (NCUs) are divided into sub-clusters, although this partition is more logical than physical.
	The archiving capability is provided as an Archiving Cluster. The Main Nodes can multiplex between the Archiving Units to distribute the load better and for higher availability when acting as proxy servers for handling incoming Archive Requests.
	This structure is not yet in place (is being defined).
	Backup of NGAS data now done by keeping an offline replication archive NGAS Disks at the observatory sites. This will be replaced by an offline tape based replication archive.