Flash Memory in the Enterprise

By Christine Taylor

Server and network advancements have commonly outstripped storage device’s ability to keep up with them. Data centers would buy powerful new arrays and attempt to keep them performing with fast-growing data by using more spindles and high performance disk clusters. This helped, but sooner rather than later the data center replaced the now-aging array with the fastest new one. And the entire cycle begins again: fast-growing data, accelerating IOPs, low latency requirements, and virtualized environments threatened to overwhelm HDD arrays.

Flash memory in the enterprise started to make a bigger splash with flash caching and Tier 0 flash for highest IOPs at a rate HDDs and traditional storage controllers cannot match. Soon some storage makers delivered hybrid arrays to markets that were fearful of the price of all-flash and that covered vendor investment in traditional HDD arrays. At the same time, vendors worked feverishly to develop all-flash arrays with a reasonable price tag that included enterprise storage services.

As 2013 wound down, 2014 saw maturing introductions of all-flash arrays whose prices were starting to match – or even undercut -- high performance disk-based systems. Just as important, all-flash storage was being manufactured with native enterprise storage services. Not all arrays offered it, and some arrays were more mature with richer services than others. But clearly, all-flash arrays in 2015 are approaching wide-scale enterprise adoption.

So if the earlier question was “Is flash performance worth the price I’m paying for it?” then the new question is “Which all-flash storage is optimal for my high-value applications?” Thus the discussion is shifting from types of flash to business-oriented discussions on how flash can and should accelerate and improve applications and business processes.

Enterprise data centers are exponentially growing their storage footprint. At the same time, critical applications like big data analytics, database performance, and heavily virtualized networks require higher IOPs and lower latency. More data centers are adopting flash storage to help them meet heavy application needs, the biggest drivers including:

Growing acceptance of flash storage advantages.

Flash’s dramatically higher IOPs performance and much lower latency.

Lowering prices for flash, especially against the cost of high performance HDDs. 

New flash-based enterprise storage services without the need for 3rd party products.

Flash storage fulfills these needs and more but flash buyers face some difficult choices.  First of all, flash storage options include all-flash arrays (AFA), all-flash appliances, server-level flash, and hybrid flash. Each option can work in the right environment, but for storing Tier 1 production data in a high performance environment, all-flash arrays are the way to go.

First let’s look at the flash storage alternatives to AFAs.

Flash appliances. Flash appliances are built from raw NAND chips instead of SSDs which are usually NAND flash with flash controllers and other components built into housing. The flash appliance maker adds the controller software outside of the flash and claims very high performance. More flash appliances are offering enterprise services in order to hit the bigger Tier 1 storage market but many of those options need to be turned on separately and can be very expensive.

Server level flash. Server-side flash with PCIe cards serves ultra high-performance, niche applications. As an application-specific flash solution it is not viable for production data in the data center. In fact, an AFA with high performance, low latency and the ability to optimize multiple workloads can serve even the highest IOPs/lowest latency applications, which will save the significant cost of server-side flash.

Hybrid arrays. Most hybrid storage products are traditional HDD-based storage systems with the option to integrate solid state flash memory in a disk drive form factor. Some hybrid arrays are still in the market but with drops in all-flash cost and the addition of storage services, there is little reason to invest in hybrids. Even HDD vendors who offered hybrid arrays primarily did so as a stopgap measure while developing all-flash products.

The Difference: All-Flash Arrays

AFAs were traditionally used for high-performance storage when traditional flash caches or hybrid arrays did not provide sufficient performance, and when users wanted storage services that were native to the array. These arrays are all about optimizing flash around data dispersion and reduction, wear leveling, zero write amplification, and more. Qualities like density, performance, storage capacity and reliability/high availability push AFAs deeper into the storage infrastructure mainstream.

Here is how it works: flash controllers are the key to performance in any flash architecture. Controller chips do the heavy lifting to manage raw flash at the chip level: writing data, managing deletion and garbage collection, and handling all-important error correction. 

Flash appliances create proprietary flash controllers to manage raw NAND chips, usually writing them in an FPGA or ASIC. That gives the vendor ultimate development control but also saddles them with proprietary development cycles.  The vendor is solely responsible for upgrading their proprietary controllers to keep pace with flash industry advancements. When an AFA vendor uses industry-standard SSDs in their array, they can leverage industry-wide developments as well as their own internal R&D. This enables AFA vendors to continually upgrade their SSDs without a correspondingly expensive controller development.

Cost Considerations

All-flash array costs are dropping but so are HDD costs, leaving AFA the more expensive alternative. Many customers look to the capital cost price tag alone as their cost consideration. Capital expense is an important factor in the cost equation but does not exist in a vacuum.

First, some AFA product costs go far beyond the simple array purchase price to include training, deployment, configuration, and extra support costs.

Second, consider application productivity gains from increased performance in the cost savings category.

Third, operating expenses should be far less with the AFA’s smaller footprint and energy efficiency.

Fourth, consider management savings. If the AFA has a rich feature set and is simple to manage, then even generalist IT will be able to successfully manage storage with a minimal investment of time and expense.

The combined total of the above is the true total cost of ownership (TCO): the cost of the entire customer experience throughout the AFA’s lifecycle.

Buyers will still want to carefully weigh costs between competing vendors. For CapEx, look for a system that will meet your needs for the next 3-5 years. Look for all-inclusive pricing including the cost of the system with storage services and required training. Treated separately, the cost of the add-ons can be more than the system’s purchase cost. Beware of low come-on prices that actually require lots of extra services and components.

This article was originally published on November 18, 2015

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