Should a Unified Computing System be able to scale to meet growing application needs? Of course, but the network must scale with it.

The problem: Cisco’s enterprise architecture doesn’t scale. And that isn’t only the StorageMojo take. Gartner VP Joe Skorupa doesn’t think so either. Here is what he said:

The promise that a single converged data center network would require fewer switches and ports doesn’t stand up to scrutiny,” Mr. Skorupa said. “This is because as networks grow beyond the capacity of a single switch, ports must be dedicated to interconnecting switches. In large mesh networks, entire switches do nothing but connect switches to one another. As a result, a single converged network actually uses more ports than a separate local area network (LAN) and storage area network (SAN).

This is not new news: uplinks have always been expensive and difficult to size. Essentially you end up with a NUMA – non-uniform memory access – architecture, which has never been popular for good reason.

Capacity cheap, network bandwidth expensive
Amazon and Google don’t use fancy switches close to the servers because a) they can’t afford to, and b) they don’t attach storage to the switches. This is why DAS – direct-attach storage – is popular in scale-out architectures.

Not only is DAS latency lower, the bandwidth is higher and much cheaper. A fully expanded 40 port 6100 switch – the one that supports UCS – is well over $1k per 10GigE port.

You can buy a low-end server for that with as much DAS bandwidth and GigE as well.

Lower latency and higher bandwidth are important for server performance as well. DAS may be tougher to manage, but it pays continuing dividends.

The StorageMojo take
The mystery of UCS – and other converged stacks – deepens. As Mr. Skorupa’s comments imply, the UCS architecture doesn’t scale well.

Cisco marketing needs to stop drinking their own bathwater and take a deep clear look at what they really have. Positioning UCS as something it cannot be is not a long term strategy for success.

Yes, Cisco and presumably the other stacks offer evolutionary enhancements over existing blade-based confederations. And compared to IBM’s z-series mainframes they seem to be more scalable. (z-series fans are welcome to weigh in with their views.)

A software layer that makes local DAS management as easy as centralized SAN management – and it should be easier – will be a big win for the enterprise. And for the company that proves they can do it.

Courteous comments welcome, of course.