A Solid State of Non-Volatile Memory

Even as a mature, diverse and reliable technology-magnetic spinning disk drives (aka hard disk drives or HDDs ) continue to grow in capacity, performance and cost benefits. Alternative storage solutions, however, continue to evolve. Hot on the HDD heels-as has been the case for more than 10 years running-are a family of solid-state equivalents.

SSDs (solid-state drives) now sit squarely alongside the other legacy nonvolatile memory solutions, and their presence is being enhanced by interface improvements known generically as non-volatile memory express or NVMe.

Storage media itself, such as Flash Memory, have seen a multitude of improvements centered on many technological advances. My previous columns have outlined those changes over the past decade. Now we see new steps to improving non-volatile memory solutions, which are in the interfaces themselves.

HDD EVOLUTION

Of the various interface forms for HDDs, those with serial Advanced Technology Attachment (SATA) interfaces

have become the more cost-effective and most prominent of the everyday application disk drives. The more expensive serial-attached SCSI (SAS) drives buy the users other capabilities.

When it comes to HDD applications, SAS drives tend to be found more in enterprise computing because of their high speed and high availability, factors crucial for such activities as ATM transactions, stock exchanges and eCommerce.

Conversely, SATA drives are used primarily in desktops for consumer use and in those less demanding roles such as backups and near-line data storage.

We are omitting Fibre Channel disk drives from this conversation because they are more specialized and less cost effective, but can arguably be justified in high-performance storage applications (such as editing systems) when supported by the appropriate operating and file system technologies.

IOPS AND RELIABILITY

Keep in mind that the best measure for HDD speed is IOPS (inputs/outputs per second), specifically when the drives are in use, under stress and with real applications designed to optimize the drives' capabilities.

To put IOPS into perspective, industry-accepted averages for 7.2K SATA drives is about 80 IOPS, with the 10K (RPM) devices offering around 120 IOPS and 15K pushing the limits of around 180 IOPS. The equations turn dramatically for solid-state storage devices (SSS), with huge IOPS improvements and no mechanical worries.

The other factor for SAS v. SATA is reliability. The industry-acknowledged MTBF (Mean Time Between Failure) for SAS HDDs is around 1.2 million hours, compared with 700,000 hours MTBF for SATA drives. This also places SAS clearly into the enterprise space.

Once you move from the HDD world to the SSD world and to other forms of non-volatile memory, the feature sets and interfaces begin to shift. Not only will speed (performance) increase, but the applications for which SSDs can be applied to help increase total system performance-not just from the storage I/O perspective.

Table 1: Some familiar, but less recognized non-volatile memory (NVM) types.

Click on the Image to Enlarge

LINK:	http://www.tvtechnology.com/expertise/0003/a-solid-state-of-nonvolatil...
	See more stories from tvtechnology

Most recent headlines