EMC DMX Technology Spurs Performance

The storage vendor rolled out three new Symmetrix offerings last week: the DMX800, DMX1000 and DMX2000. Instead of using switches or buses to connect key functional blocks, the DMX technology connects the blocks directly in all possible combinations, thereby reducing bottlenecks to the theoretical minimum. That has the added advantage of maximum fault tolerance, since traffic would automatically be routed around any failed subsystem.

In a bus-style architecture, all of the server cards are connected to all of the cache cards through one bus. Likewise, all cache cards are connected to all storage controllers through another bus. Because the buses are shared, they can get swamped with traffic, and their bandwidth is the maximum for the architecture.

Switch architecture is better, since the server cards, the cache cards and the controllers are connected through multiple switches via multiple routes.

Although all of the subsystems have their own route to one another, the switches have to direct all of the traffic, making them the weakest link.

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The DMX architecture dispenses with buses and switches by connecting multiple server cards directly to multiple cache cards. The cache cards, likewise, have their own connections to multiple storage controllers. Each connection has a bandwidth of 500 MBps. Taken in groups of 128 server cards cross-connected to 128 cache cards and, in turn, connected to 128 controllers, the total data-path bandwidth reaches an impressive 64 GBps. The command layer has its own 6.4-GBps pathway.