The Nexus 5020 is a 2U rack mounted unit and packs in that small space an astonishing number of sockets: 40 to be precise. Each socket can host Ethernet ports running at 10G. Using an optional expansion module (the switch has room for two), you can extend connectivity with six more 10G Ethernet ports, eight more FC ports, or a combo module with four FC and four 10G Ethernet ports.
However, those sockets don't need to be completely filled. For example, my test unit had only 15 10G ports and 4 FC ports active. At review time the Nexus 5000 offered support for all FC connectivity speeds, up to but not including 8G.
Typically, you would deploy the 5020 in the same rack where your app servers reside, or in an adjacent rack. Considering a resilient configuration with two 10G connections for each server, two Nexus 5000 can connect up 40 servers and still have room for more ports with the expansion modules.
The front of the 5000 hosts five large, always spinning and rather noisy fans. With only one power supply (a configuration with dual PSU is also available) I measured around 465 watts absorbed by the switch. Interestingly, the Nexus kept running when I removed one of the fans but, as I had been warned, shut down automatically when I removed a second fan. However, the remaining three fans kept spinning to keep the internal electronics cool.
When reinserted, the two fans I had removed began spinning immediately, but the rest of the system was still no go and I had to power cycle to restart. Taking advantage of this behavior (it's by design), I measured 243 watts with only the five fans spinning, which suggests that the power usage of the other components of the switch is the delta to 465 watts, at least in my configuration.
Having more connections would obviously push up that number, but the consumption I measured seems to be in the same ballpark of what I read from the specs of 20 ports 10G switches from other vendors.
Policing with a policy
Obviously, the most important novelty that the Nexus 5000 brings to a datacenter and the greatest differentiator with other, single protocol switches is that Ethernet and FC are just two supported applications that you monitor and control from the same administrative interface.
With that in mind it's easy to understand why the Nexus runs a new OS, the NX-OS, which, according to Cisco, inherits and brings together the best features of their Ethernet-focused IOS and their FC focused SAN-OS.
To access the OS features administrators can choose between a powerful CLI or the GUI-based Fabric Manager. I used the plural because the administrative tasks of the switch can be easily divided between multiple roles, each with a different login and confined to a specific environment, as defined by and under the supervision of a super admin. That's a critical and much-needed option if you plan to bring multiple administrative domains and their administrators under the same banner.
This and other configuration setting of the Nexus 5000 are policy-driven, which makes for easy and transparent management. Another remarkable feature is that you can define classes of service that logically isolate different applications.
For example, after logging in to the switch, a simple command such as "sh policy-map interface Ethernet 1/1" listed all traffic statistics on that port, grouped for each CoS (class of service) and listing separated numbers for inbound and outbound packets.