SSDs change infrastructure

 August 10, 2011, Flash Memory Summit, Santa Clara, CA—John Scaramuzzo from SMART Modular described SSDs in the enterprise as a transformational disruptive force. These drives have changed the nature and costs of infrastructure for many businesses.

For comparison, a 15k HDD is about 500 times slower than a SSD in IOPS terms. An SSD uses about 50 CPU cycles for an access while a 10k HDD can take up to 10,000 cycles. This level of performance changes the way applications are used and shows how SSDs can deliver memory-class performance at greatly reduced costs.

The IT organizations are leading the way to new uses and capabilities. Facebook has increased SSDs 400 percent over HDDs. Procter and Gamble has reduced a financial management analytics run time from months to days. T-Mobile reduced workforce planning from one month to hours. All of these examples show reduced time and cost for IT operations, but also show a need for changes in infrastructure and workflows.

The total cost of ownership is a concern for many enterprises, and the decision to change from HDDs to SSDs depends upon the workloads as well as the need for endurance, reliability, and performance. Cloud and server functions that are read-mostly are likely candidates for application acceleration.

For the mainstream user, these solutions are too costly. Average users need a drive that uses 7-10 drive writes a day, so SLC is overkill. Instead, eMMC is a viable alternative and the enterprise-level units can be selected from the mass at test. Users need plain MLC flash with sustained performance for their system. The tradeoff is NAND cost versus reliability versus the additional memory for ECC.

HDDs use aggressive signal processing technologies to improve from a native BER of 10-4 to over 10-16 and similar variable density techniques are possible for SSDs. Endurance is another area where significant change is possible. Current techniques assume uniformity in all media, and end up with the lowest common denominator for media lifetimes. There are many parameters available for optimization and active management techniques could change those parameters as conditions and usage change.

Standards would be nice, but he uses models vary too much to be useful. HDDs need tuning to match head and media for optimal performance and lifetimes. NAND also needs tuning, so the NAND manufacturer and the SSD designer need to work together to know what the knobs are and how to tune them. These adjustments are manufacturer specific, so the concept of drop-in replacements is not entirely realistic.