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Quarch XLC Programmable Power Module Review

Quarch XLC Programmable Power Module Review
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Our search for the one device that measures the power consumption of every type of storage device ends with the Quarch XLC Programmable Power Module.

We utilize several of the Quarch Technology XLC Programmable Power Modules (XLC PPM) in our busy test lab to measure the power consumption of every type of storage device, including HDDs and SSDs in SAS, SATA, PCIe AIC and U.2 form factors. One of the most attractive features of the XLC PPM is its ability to displace multiple pieces of equipment, such as two bench power supplies, two scopes and two current probes, with one small device.

Power consumption is often one of the most overlooked metrics during product evaluations, but for those in the know, power consumption characteristics are one of the most important considerations of any deployment. Data center architects of all ilk's, from the massive 500,000-square foot hyperscale designs to server closet builds, view power consumption with a keen eye due to its long-term cost overhead. It also factors directly into the secondary cooling equipment requirements, and thus the amount of floor space available for compute/storage.

The first concern is total cost of ownership (TCO). A rough calculation of average power costs (which can vary widely) approximates a cost of $6 per watt per year. On the surface this seems trivial, but a typical enterprise HDD can consume up to 11 watts under load, which means a single HDD can add up an to additional $330 of power costs during its service life (assuming a full load for the duration of its five-year warranty). Most enterprise 6TB SATA HDDs retail under $300 at online retailers, and after volume discounts they can weigh in under the $250 mark, which means powering the device is more expensive than procuring it. 

Performance workloads are migrating to SSDs and architects are employing denser HDD-based storage designs, so packing in the most 'cheap and deep' HDDs as possible into a single enclosure is becoming more common. Some 4U racks can house up to 90 HDDs, and for the purposes of our mental exercise we can see that the power consumption of the densest possible HDD deployment over five years can cost up to a quarter of a million dollars per rack. Our example is admittedly under the worst-case circumstances, but the hidden costs of power consumption are evident even in smaller deployments.

Power is also a double-edged sword because it invariably generates heat. Data center cooling has evolved rapidly over the last decade and even open-air data centers are becoming more commonplace, but these are relegated to cutting-edge hyperscale operations.

Unfortunately, open-air and exotic cooling methods are not realistic in most applications; the majority of deployments still utilize chillers and standard CRAC (Computer Room Air Conditioner) units. Computing and storage equipment emit power as heat, and the more heat emitted the more air conditioning is required, which equates to more cost and also less available floor space for compute. Chillers also require considerable amounts of water and the associated infrastructure to manage it.

Finally, in the data center each watt of power requires redundancy, which typically involves either/or generators, batteries and sophisticated infrastructure. This again adds more cost and complexity while reducing the amount of usable floor space.

SSDs tout lower power consumption metrics, and in tandem with their high performance, they offer a much more efficient form of storage. As a result, administrators often overlook SSD power draw, but it can be a clear differentiator between products.

The key to comparing storage products is to utilize an accurate and flexible power measurement tool that can measure storage devices in all of their various forms. The XLC PPM provides 5V and 12V outputs for SAS and SATA devices and a 3V3 output for PCIe devices. The modules come in standard and XLC (eXtra Low Current) flavors. The XLC module offers measurement accuracy down to 100uA (micro amps), which is well below even the stingiest power consumption offered in many SSD standby modes. The XLC PPM also features eight times the memory buffer of the standard module.

The accurate power measurements, and the ability to record power consumption over long periods of time, allow us to present incredibly granular power consumption and long-term efficiency measurements. Let's take a closer look at the module.

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