SSDs are commonly used these days as replacements for hard disk drives (HDDs) in high-end laptops and hybrid portables, but they’ve also been making their way into the data centre as a faster way for servers to store and retrieve data.
The latest figures from market research firm TrendFocus show that the average capacity for a data centre-class SSD reached more than 1TB in the second quarter of this year, and that shipments in the enterprise space have been rising dramatically. In the first quarter of 2015, 2.23 million units shipped to enterprise customers. In the second quarter of 2016, that number had almost doubled to 4.07 million.
SSDs used to be a rare thing in computing. These flash storage devices are far faster than their spinning hard drive counterparts, because they don’t rely on mechanics when reading and writing data to drives. An HDD has to spin its disk and move its read/write head to place it at the exact point necessary to store and retrieve data. When that data is spread randomly across a disk, the time overhead increases.
Conversely, SSDs write the data electronically into non-volatile memory that preserves it until needed. The result? A substantial increase in the input/output operations per second (IOPS), which is a way of measuring the speed of writing your data to disk and getting it off again. IOPS on an HDD typically range in the hundreds or very low thousands. Conversely, SSD IOPS are typically in the tens or even hundreds of thousands, depending on their design.
This means the primary application for enterprise SSDs is performance. “The very first adopters of commercial-grade SSDs a decade ago were financial traders, who would buy a $2,000 SSD and see it pay for itself in the first 30 seconds of trading,” recalls Jim Handy, general director at semiconductor research firm Objective Analysis.
Because it is relatively easy to measure the performance benefits, online transaction processing (OLTP) applications were next in line. The faster that a company can make a ticket booking, insurance claim or retail order entry, the more viable the whole thing becomes.
Experts hope that SSDs will find more traction for other reasons. Vendors are talking up the total cost of ownership benefits for the technology, arguing that performance tells only half the story.
For example, SSDs typically use far less power than a hard drive, which has to spin a chunk of metal at speeds of up to 15,000 rpm. You can get power consumption of 2.2w when writing data and 1.9w when idle for a Samsung SM863 SSD, which operates at 6GB/sec using a SATA interface. A HGST UltraStar HE8 enterprise hard drive — designed with power consumption in mind — running on the same SATA interface will slurp up 7.4w when reading/writing and 5.1w when idle.
Scale this over many devices and the power savings begin to mount up. And as a rule you’re getting far more IOPS for the power you’re using with an SSD, which brings us to the other TCO benefit: you’ll often need fewer SSDs to deliver the same amount of low-latency data.
Let’s say your enterprise needs to stream video to large numbers of users. That requires a significant amount of storage throughput. A single HDD might not be able to give you the IOPS you need to shift all of that data quickly enough to deliver it at speed. Instead, you might need to spread your video files across lots of HDDs to take advantage of the combined IOPS they need. Because a single SSD provides far more IOPS, it can serve far more users than a single HDD, potentially requiring fewer components.
All of these benefits make SSDs especially suitable for large IT operations where TCO benefits and performance gains accumulate at scale. The problem for smaller IT operations is that while some of the benefits are still there, the cost is still high. The big barrier for SSDs is price, because on a per-gigabit basis they cost much more than HDDs.
The price issue is changing, though. The falling price of NAND flash — the silicon on which SSDs are based — is driving down the cost of components in both the enterprise and consumer sectors. At its Global SSD Summit this year, Samsung said the post-gigabit price for SSDs stood at $1.17. Now, prices sit at $0.36, meaning they have plummeted more than two-thirds in just four years.
Currently, the higher price per gigabit for SSD over HDD will still be cost-prohibitive for some. This will change in the next five years as the gap narrows. Samsung believes a 256GB SSD will cost the same as a 1TB HDD by 2018, while a 512GB SSD will cost the same as a 1TB HDD by 2020.
That all makes SSD sound like an increasingly solid bet.