The other two models are both double-wide blades. The Cisco UCS Express 140D (we tested a beta version of the 140D) and 160D are four-core and six-core double-wide blades. With a little more real estate, these come with three DIMM slots (up to 48GB of memory) and three 2.5-inch drive bays. If you want to put more than one of these in a chassis for some reason, there's a complicated set of rules about how many UCS Express servers will fit in ISR G2, considering space, cooling and power requirements, available on the Cisco website.
Booting up UCS Express
Getting started takes a little rethinking because two of the Ethernet ports on the UCS Express blades are internal to the ISR G2 router. Rather than connecting all four of the Ethernet interfaces to the network, we connected the two physical interfaces, and then went into the ISR G2 command line to control the two internal interfaces. Once you figure all this out which takes about 30 minutes, tops then testing UCS Express is a breeze.
Because the blade is integrated into the router, we wouldn't expect to use the video and keyboard ports on the blade very often, although they are available. Instead, the UCS Express blade uses the same lights-out management system as Cisco's larger UCS servers, the Cisco Integrated Management Controller (what Cisco calls a baseboard management controller, or BMC).
Each UCS Express blade gets its own IP address for management, which can be connected either internally through the ISR router, or via an externally accessible dedicated management port.
The particular nature of the integration between the UCS Express blade and the ISR G2 router does present a few restrictions. Because the ISR G2 is normally a router, not a switch, you can't just sling virtual machines onto virtual LANs, unless you've installed some additional hardware to enable Ethernet switching.
This means that VMs running on the UCS Express blade will generally be routed, not switched, when talking through the internal Ethernet connections. That may be fine or even desirable in some topologies, but it can also be a confusing restriction to system managers used to having all of their servers on the same subnet.
It's easy to work around this problem by running a physical Ethernet cable from one of the external Ethernet ports on the UCS Express blade to a switch somewhere in the network, but this adds complexity and a potential failure point. None of this is a show-stopper, but it is something to think about before committing to a large-scale deployment of UCS Express blades in branch offices.