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For testing, Dell sent the CRN Test Center a PS6110, the 10 GB version of the array populated with 24 900-GB 2.5-inch 10k RPM 6 GB/s SAS drives. This unit was equipped with redundant controllers, each with two 10 GB/s interfaces plus management and serial ports. To test its fault tolerance, we simply unplugged a data cable while testing the array's performance. It never missed a beat. As for throughput performance, PS6110 was able to handle as much as IOmeter could throw at it. In other words, our test fixture was unable to reach the unit's maximum performance potential.
Dell also sent CRN a PS6100 4U array fully populated with 24 3.5-inch 3 TB 7200 RPM 6 GB/s SAS drives. By the way, Dell has discontinued use of SATA drives altogether. It will continue to supply replacement drives for all drive types currently in use in the field, but new deliveries will be provisioned only with 6 GB/s SAS drives.
The PS6100 and its 1 GB/s interfaces also performed as expected, maxing out IOmeter and our text fixture with hardly a notice. It too was equipped with redundant controllers, each with four 1 GB/s Ethernet ports plus management and serial ports.
When it updated its firmware to version 5.1 last fall, Dell added the ability to automatically perform load balancing and optimize latency between arrays. According to Junker, Dell implemented this in such a way that it maintains the same capacity balancing but swaps what it calls hot and cold pages. "It's always evaluating and performing active load balancing withing a pool, but if you had SSDs in an array, the hot pages would migrate to those."
Also new in 5.1 is data center bridging, which can allocate segments of available bandwidth for certain applications. "Let's say you're a media company doing live broadcasts," Junker said, for example. "You wouldn't want a production person to be able to grab full bandwidth when rendering a video and put your live broadcast off the air." The technology would permit, a percentage of the pipe to a particular class of application. DCB is intended to interoperate with converged environments such as those incorporating Fibre Channel and Ethernet. It works only in Dell's 10 GB/s arrays and requires DCB-aware switches and NICs on all ends.