Technology - Violin Switched Memory (VXM)

Violin Switched Memory (VXM)

Violin Switched Memory (VXM) is a radical, patent-pending, redesign of memory systems for large dataset applications. Instead of the traditional bus topology, a switched network topology is used. The switched topology provides the following benefits:

	Scale: A single memory controller supports 4000 or more memory devices.
	Latency: The latency through a switched network is similar or better than a repeated bus network.
	Bandwidth: The sustained bandwidth of the network is high for both random and linear accesses.
	Fault Tolerance: The network copes with one or more module losses without loss of data and application interruption.
	Power: The heat and power per GByte required is 75+% lower than a repeated bus network.
	Flexibility: The switched network supports memories of different sizes, speeds and types within the same system.

The topology developed for VXM is unique and based on 3 port switches in each of the Violin Intelligent Memory Modules (VIMMs). Each VIMM has a Violin Buffer (VB) device which both implements the 3 port switch and also provides local memory controller functions, which are specifically related to the type of memory being used (e.g. RAS/CAS refresh commands). The central memory controller provides higher level functions such as the mapping of logical address space to the specific physical VIMMs and memory devices.

The topology shown below is used in the Violin 1010 and allows any two modules within a large network to fail without loss of connectivity to any of the other modules.