The gigabytes equal performance illusion

GB Labs Ben Pearce discusses why its so important for content owners to choose their storage systems wisely

By Contributor

Published: September 10, 2020

GB Labs' Ben Pearce discusses why it's so important for content owners to choose their storage systems wisely

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I've been working with network area storage (NAS) for nearly 20 years and still see too many people buy what is clearly the wrong storage for what they need. Often, their decision is not based solely on perceived cost savings, it is usually a result of not fully understanding that the operative word is shared storage, meaning that the storage is about providing support for multiple files to multiple users. Looking at storage as a single purpose appliance has often proved to be short-sighted.

What I'm saying is that measuring peak performance and IOPS (input/output operations per second) as standalone criteria for purchasing a storage system is a mistake because those figures are often misleading. A single peak-performance figure provided by a manufacturer is not indicative of the totality of what a storage system can provide to a specific facility at which it is deployed. A high peak-performance figure may sound impressive, but doesn't take into account multiple file access requirements that take place in a typical shared storage environment, so that figure is more applicable for DAS (directly accessed storage) systems. In short, IOPS are almost meaningless unless you know exactly what parameters were configured in the tests that were performed to arrive at that figure.

It's too easy to arrive at misleading figures that promise false economies. The issue is that sales collateral that emphasises peak performance and IOPS figures are so prevalent that they distort the truth and lead, in many cases, to unhappy users when they subsequently find out that the claims on which they based their purchase decision bear little resemblance to real-world performance.

Back to basics Hard drives come in many shapes and sizes, from many different manufacturers, and each manufacturer chooses what to adopt and promote from numerous storage model types and technologies.

What many end users don't always grasp is that storage capacity alone is not a good measure of its ability to perform the tasks they need a storage system to do or to eliminate the bottlenecks they are buying it to fix.

It's common for people to want, indeed expect, high, 24-hour duty cycle performance from a high-density RAID. But to achieve that, you need a very specific type of hard drive that comes at a higher cost than the consumer-grade drives that many assume will be good enough . And, like many things when you decide on a cheaper, good enough option, it soon costs even more to retroactively put right.

Thinking outside the capacity There are many aspects other than capacity that impact storage system performance and reliability. For example, communal backplanes that address RAIDs inside NAS storage; the storage interface; and the number of paths and the quality of the host-based adapter (HBA) also play key roles. However, the benefits of getting these areas right are often overlooked in favour of focussing solely on greater capacity or lower cost. Again, too many people consider price-per-terabyte to be the sole purchasing parameter rather than taking a more holistic view that encompasses the entire spectrum of what a system can do when it's designed, configured, and deployed to take advantage of a system's entire range of capabilities. To get optimal performance, all of those aspects must work together.

Think of it this way: A race car that is installed with a very powerful engine, but with a too light chassis, standard gearbox and high street tyres to save money, is likely to spend more time in the garage than out of it, let alone ever be competitive in any races.

The best way around this somewhat short-sighted decision-making is to fully understand the potential ramifications of choosing the least-cost option. Ask detailed questions.

For example: Is the RAID level achieved in hardware or software? There are advantages and disadvantages to achieving the RAID level with either approach, so it's important to find out which will work best for what you want to do. In some cases, it might be that a hybrid hardware and software-based RAID level system is the most appropriate option, but too many find this out after they've already installed a relatively cheap storage system that has little or no chance of delivering what they need. And all because they didn't ask anything other than, How much per terabyte?

The OS is everything I've been discussing questions to be asked and choices to be made concerning purchasing NAS, but I want to identify the main differentiator of any NAS, and that's the operating system (OS) on which it runs.

No, I'm not talking about Windows or Mac. With NAS, the limitations of those operating systems are quickly reached and exceeded by NAS systems running on powerful hardware. Off-the-shelf operating systems are not suitable platforms for any professional shared storage system.

Nevertheless, the vast majority of NAS storage systems on the market today use generic, OTS operating systems that purport to turn hardware servers into functional NAS. The problem with that approach is that they must cater for a wide range of different hardware configurations from good to bad, which means that they are specifically tuned for none and even for those they can operate requir

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