One of the main issues of storage is slow data access times, basically caused by the limitations of spinning disks, which must be searched sequentially at a speed determined by their spin rate. As disk capacities have grown while disk speeds have remained essentially unchanged,  that problem has exacerbated. It is particularly acute for users of ERP, CRM, and other very large database systems, where data access is gated by data lock/unlock speed, which crawls on even high-speed SAS systems.

The traditional strategy for ameliorating this problem is to copy heavily used data into RAM cache. This boosts performance hugely, but only for the data in the cache. Every time the system has to go back to the disk, performance, and therefore quality-of-service, dies, and these hickups can add up to a major hit in overall productivity for employees who use these systems intensively.

In his article, Impact of Flash-only Arrays on Storage Access Time Variability, Wikibon CTO David Floyer documents this problem and argues that the best answer is not adding more RAM cache but rather replacing the disk drive and cache with a non-volitile NAND Flash system such as the Fusion-io system.

The price of flash has dropped to a range that makes it competitive with the traditional SAS drive/cache system, while its read/write performance is nearly equivalent to that of RAM and an order-of-magnitude greater than spinning rust. The real impact, Floyer argues based on actual experience of Wikibon community members, is often in huge, measurable improvements in productivity for employees who are no longer constantly frustrated by long waits while the database works through the lock/unlock cycle. And with critical data always available essentially instantly, service quality to customers rises substantially.

This article is a must-read for CIOs of companies whose QoS is gated by the response times of their ERP, CRM and similar systems. And that impact is not limited to large enterprises, Many medium-sized companies are just as dependent on their ERP systems, and some are already shifting to flash solutions as a less-expensive alternative to upgrading their existing SANs.

image credit: Gideon Burton