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Preview: Promise Pegasus R4 (SSD Version)

Nine External Thunderbolt Storage Devices, Rounded Up
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Promise plans to release an SSD-based version of the R4, but has not yet decided on a specific drive model to use yet. We are told that Intel's 240 GB SSD 520 is a strong contender due to the company’s stellar reputation for reliability and the zippy performance delivered by SandForce's second-generation controller.

Promise does not anticipate selling an SSD-based R6, stating the added cost of six SSDs would would push the price of the R6 beyond what the market will bear. We don't have an estimate for what the R4 with solid-state storage will cost, either, so we were forced to create our own estimate. Using the current 4 TB R4 as a baseline, we assume the 1 TB Hitachi 7K1000.D Deskstar hard drives are about $100 each, with the chassis and components totaling about $750. A single 240 GB Intel SSD 520 runs just north of $300, so a four-SSD variant of the current R4 could conceivably weigh in under $2000.

What this quad-SSD R4 variant might offer will depend on what you compare it to. Next to the R6, its benefits are likely to be limited. In theory, sequential performance should speed up by 5-10% (50-100 MB/s), while random I/O improves by an order of magnitude. Achieving better random throughput is important for certain applications that a hard drive-based solution simply cannot address. However, LaCie's Little Big Disk is more effective with its two SSD 320s than Promise's R4 armed with four SSD 520s when it comes to random performance.

The SSD-based R4's throughput matches what you can achieve using a hard drive-based R6. However, that performance gain costs lots of capacity. Even sporting 240 GB drives, the R4 tops out under 1 TB of space. That's nowhere near enough room for data-dense multimedia applications that chew up multiple terabytes.

Perhaps the characteristics of solid-state storage make this particular R4 more attractive, though. If you have production equipment operating in a vehicle, for example, or are constantly moving drives from one place to another, SSDs prove far more resilient against physical shock. They also run a lot cooler and use a lot less power.

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