Flash storage: Dissecting the performance of an industry benchmark

Flash storage has come into its own and is now arguably viewed as the industry benchmark for storage. With the market growing at a rapid rate, innovations have moved from a smaller scale into the mainstream and performance is at the heart of this modernisation.

For over ten years, NAND flash has been a primary component of data storage. Early on, there was quick user adoption of USB thumb drives using flash. These days, we see storage admins in enterprise data centres using storage arrays that are based on SSDs and proprietary flash.

Modern data reduction techniques such as inline deduplication, inline compression, and some server virtualisation APIs, such as VAAI, help flash-based storage provide faster, more reliable, and feature-rich storage using commodity hardware by way of servers and SSDs.

In the never-ending quest for better performing storage, flash in a denser form factor has a high adoption rate among users. In fact, for modern data centres that rely on server virtualisation, flash storage has proven to be revolutionary in terms of performance gains. In this article we’ll take a look at the importance of flash storage when it comes to performance and what this means for businesses.

What does storage performance mean?

In layman’s terms, faster performance means moving more IO between storage and server in a shorter time compared with the previous storage system. In the days of storage based on spinning disk, IO performance was limited by the number of spindles. Customers needed to buy a large number of spindles - essentially a shaft that holds rotating hard disk drive HDD) in place - in order to achieve a higher number of IOPS (Input/Output Operations per Second).

Flash storage completely changed what is required for IOPS. Now, storage admins can choose a smaller storage size for their array and still get ample IOPS in a smaller form factor, plus get data reduction functions such as inline dedupe and compression for the 5+ year life of the storage array.

Additionally, applications need to use less CPU cycles to access faster flash storage, thereby reducing CPU requirements for applications. There are advantages to users where the application is licensed by CPU core/socket: users can run the same application in fewer cores and reduce their licence bill. The savings from buying fewer cores can be reinvested into buying faster flash storage. Some of the top performance parameters for flash storage include:

  • Block size
  • IOPS
  • Latency
  • Bandwidth/Throughput

What does flash storage offer that legacy systems cannot?

NAND has a wear life that is much worse than its predecessor, the spinning disk. Typically SSD vendors use different levels of over-provisioning in the same capacity to differentiate between enterprise and consumer storage. Different array vendors use different types, for example, E-MLC and C-MLC. Array vendors cite different reasons why one type is better than another type. The reality is that as long as an SSD lasts five years (or whatever the array vendor claims) and the SSDs are supported under warranty, the type really should not matter.

SSD technology continues to improve. SSDs are getting faster, denser and cheaper every year. At the same time, storage software that runs in the controller for performance and storage efficiency performance, such as deduplication and compression, is getting increasingly ‘smart'. As the technology matures to take advantage of reduced wear life characteristics of the newer SSDs, this ‘smart’ storage software makes sure the SSD lasts five or more years.

Writes have a penalty in MLC Flash, as an entire page has to be re-written for a block of write on a page. So, rewrites are not possible. Storage software takes care of this by ‘collecting multiple writes’ and writing them in an ‘aligned burst'. Additionally storage software features such as inline deduplication and compression enable 'write less' to flash for duplicate blocks and compressible data.

Flash storage performance

Flash storage has revolutionised today’s data centres in primary storage by providing faster and cheaper storage. SSDs are getting denser, better and cheaper every year and are expected to kill spinning disk. By taking a deeper look and dissecting the performance of flash storage, businesses will undoubtedly see an improvement in their bottom line.

Paul Silver, VP EMEA at Tegile

Image Credit: Shutterstock/Ralwel