Intel Smart Response Technology - SRT
Cache I/O isn't a new advancement in storage technology but does play a large role in the future of storage on many Intel systems. Today we look at Intel's new Smart Response Technology and give our thoughts while keeping an eye on the future of consumer storage advances.
Intel is among a small list of solid state controller manufactures producing enthusiast class products. By nature, SSDs are still considered premium products with large performance benefits over traditional platter based hard drives but the performance isn’t what constitutes a premium category listing. SSDs cost considerably more than traditional spinners and the cost vs. capacity ratio is much higher. Technology improvements have brought this ratio down for SSDs but the same can also be said for traditional HDDs as well. For some, the imbalance is just too wide to consider a move to high speed, low capacity solid state technology.
Solid state technology improves the user experience two ways, one you can see and one you can feel. They say seeing is believing and it’s possible to show with graphs and plotted lines sequential performance. SSDs are now capable of delivering 500MB/s read and write speeds when asked to perform a straight sequence. This is a 3x increase over the highest performing traditional HDD. A 3x increase in what’s still the slowest performing component in your computer system is significant but it’s not what enhances the user experience in day to day tasks. To put this into a personal perspective, ask yourself how often you transfer a DVD, Blu-Ray ISO or other large file from one location to another. These are sequential tasks.
While you are questioning yourself go ahead and ask how often you open a web browser, application, turn on your PC and for that matter double click on anything found on your boot drive. SSDs sequential read and write speeds get most of the marketing attention because big numbers look better in advertisements. The user experience comes from small numbers, numbers measured in microseconds.
When you double click on an icon you start a series of actions into motion. With spinners the arms holding read heads must move to a precise location and wait for spinning disks to move the data into place. The time it takes for this action to take place is called access time and a good round number for platter drives access times is around 10ms (milliseconds). 10ms sounds like a very small number and to tell the truth, it is. The problem is that 10ms is what it takes to read one block, a small section of data. You are trying to read several blocks and must do so before your program opens. This is why large programs such as Photoshop take so long to open; many blocks of data must be read to open the program. In contrast, SSD’s access time is measured in microseconds. I typical SSD is able to read a block of data in around .2ms. This is achieved by the direct nature of the data to the controller. Data is held on flash chips that are directly accessed by the controller so the mechanical functions of platters and read heads are omitted. It’s like playing a full size piano with a finger on every key all the time. Without needing to move your hands the latency between each key press is much shorter. If your intention is to play as song as fast as possible those with 128 fingers would finish much faster than those with just 10.
With SSD sequential speed and data access feel out of the way we can now turn our attention to cost and ways to improve cost, performance and capacity at the same time. Today we will look an emerging technology that is destined to play a pivotal role in storage technology for years to come. Personally I like to call this technology IO Caching. Two years ago I started exploring the theory and practice of holding frequently accessed data on a high speed SSD while holding nearline data, data that is accessed routinely but not frequently on a slower, high capacity drive. The technology is not as new as some will make it sound today. I/O Caching can be traced back to datacenters where high speed access is required for some data but archived data is also required. The technology has been scaled down from the enterprise cabinet and made its first affordable appearance with products like the Adaptec MaxCache, LSI CacheCade and even a consumer specific product from SilverStone Technology called HDDBoost. All of these components worked with varying degrees of success and the HDDBoost product was quite affordable. As add on solutions, they all increased the cost of a system or server but the technology is now ready for mainstream products with the capability on board.