The result is a fairly speedy I/O subsystem that can deliver a terabyte or more of fast and reliable storage based on local hard drives.
For CPUs in the UCS Express blade family, Cisco has chosen the low-power version of Intel's powerful E3 and E5 processor family, but these are still very hefty processors. For example, the low-power Intel E5-2418L quad-core processor at 2.0GHz has about the same performance as an Intel Core i7 quad-core processor at 2.7GHz.
Combining this with a fast on-board I/O subsystem and, most importantly, plenty of memory makes the Cisco UCS Express blade perfectly capable of handling multiple virtual machines at the same time.
To test this, we used three different VMs: two simple Linux systems running CentOS 5.9 and a third running the open source Vyatta router. We fired up all three VMs and then used the iperf network performance testing tool on both Linux VMs to pass traffic through the third VM as fast as possible. Since the traffic was passing through four network interfaces, the maximum 600Mbps (without errors) we achieved translates to a total system throughput of about 2.5Gbps.
Meanwhile, CPU load on the UCS Express blade was only 21%, indicating that our UCS Express blade had plenty of firepower leftover.
The $64,000 question
We were pleased to see that the Cisco UCS Express blade was easy to configure, fast, elegantly managed and powerful enough to run multiple virtual machines. Now comes the hard question: Should you use it?
Certainly, for network managers who need a way to deploy virtual machines for network-specific tasks, the UCS Express blade makes a lot of sense, because it dramatically simplifies deployment and management of VMs and because it's easy to switch the different VMs onto different subnets, entirely in software.
However, for system managers considering replacing on-site servers with Cisco UCS Express blades, the decision is not so simple, because the UCS Express blade does not have the same expansion capability as a typical rack-mount server.
For example, the UCS Express does not have external SCSI ports, making backup to a tape drive difficult. Cisco does offer the "DP" version of the 140D and 160D, which trades off one of the disk drives for a PCI slot, but now you've lost one-third of your storage capacity and some potential redundancy.
Even if the UCS Express blades are not as expandable, Cisco does claim that they will be as reliable, if not more reliable, than stand-alone servers, especially when installed in ISR G2 routers with dual power supplies. Cisco equipment has an amazing reputation for surviving forever in the dusty and hot environment of wiring closets, which gives Cisco credibility when it claims high reliability for the UCS Express blades.
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