Revolutionary. Cutting edge. State of the art. These are words and phrases that are bandied around so very many products in the IT field that they become useless, bland, expected. The truth is that truly revolutionary products are few and far between. That said, Cisco's Unified Computing System (UCS) fits the bill.
To fully understand what Cisco has done requires that you dispense with preconceived notions of blade servers and blade chassis. Rewire your concepts of KVM, console access, and network and storage interfaces. Reorganize how you think of your datacenter as islands of servers surrounded by storage arrays and networks. Cisco had the advantage of starting from scratch with a blade-based server platform, and it's made the most of it.
In short, UCS is built around a familiar concept -- the blade chassis -- but rearchitects it to enable both greater manageability and greater scalability. This article focuses on the nitty-gritty details of UCS, and my experiences working with the system in a recent visit to Cisco's San Jose test labs.
UCS building blocks
A Cisco UCS chassis provides eight slots for half-width blades, each equipped with two Intel Nehalem processors, up to 96GB of RAM with 8GB DIMMs, two SAS drive slots, an LSI Logic SAS RAID controller, and a connection to the blade backplane. In addition, each blade is outfitted with a Cisco Converged Network Adapter, or CNA. The CNA is essentially the heart of the system, the component that makes UCS unlike traditional blade systems.
The CNA is a mezzanine board that fits a QLogic 4Gb Fibre Channel HBA and an Intel 10Gb Ethernet interface on a single board, connecting directly to the chassis network fabric. The presentation to the blade is two 10Gb NICs and two 4Gb FC ports, with two 10Gb connections to the backplane on the other side. The initial release does not support multiple CNAs per blade, or really even require one. But the CNA is integral to how the entire UCS platform operates, as it essentially decouples the blade from traditional I/O by pushing storage and network through two 10Gb pipes. This is accomplished through the use of FCoE (Fibre Channel over Ethernet). Everything leaving the blade is thus Ethernet, with the FC traffic broken out by the brains of the operation, the Fabric Interconnects (FI).
So we have some number of CNA-equipped blades in a chassis. We also have two four-port 10Gb fiber interface cards in the same chassis and two FIs downstream that drive everything. It's not technically accurate to call the FIs switches, since the chassis function more like remote line cards populated with blades. No switching occurs in the chassis themselves; they are simply backplanes for blades that have direct connections to the FIs. Physically, the FIs are identical in appearance to Cisco Nexus 5000 switches, but they have more horsepower and storage to handle the FCoE to FC breakout tasks. They offer 20 10Gb ports, and they support a single expansion card each.
The expansion cards come in a few different flavors, supporting either four 4Gb FC ports and four 10Gb Ethernet ports, or six 10Gb Ethernet ports, or eight 4Gb FC ports. This is in addition to the twenty 10Gb ports built into each FI. There are also three copper management and clustering ports, as well as the expected serial console port. The FI is wholly responsible for the management and orchestration of the UCS solution, running both the CLI and GUI interface natively -- no outside server-based component is required.
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