Caching is King: Assessing Top PC Storage Options for Tomorrow
Caching is King: Assessing Top PC Storage Options for Tomorrow
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In a perfect world, we would all run super-sized solid state drives (SSD) in our systems and have extra money to upgrade them every year or two. But with 960GB SSDs now ringing the register for US$1000 or more while Newegg has a 4TB Seagate® Desktop HDD for US$190, we have a price-per-gigabyte disparity of roughly US$1.00 (for SSD) compared to US$0.05 (for HDD) when buying the highest capacity available. Obviously, most buy SSDs for their performance and HDDs for their inexpensive capacity, and the gap between these two has been holding fairly steady in recent years.
Between these two storage options, however, we now have a rising number of caching technologies vying to provide a happy medium. Do any of these approaches make sense for your current and future systems? Let’s dig in and find out.
The Two-Pronged Approach
In this context, caching entails using some amount of NAND flash (solid state) memory as a high-speed storage repository for the most frequently accessed files. Meanwhile, the majority of files, most of which may go untouched for weeks—even years—at a time, can reside on standard magnetic platters.
NAND flash can be implemented in different ways. One basic approach that has been popular since low-capacity SSDs started falling under US$200 involves simply using an SSD as the system boot drive, where the operating system and most commonly accessed applications are installed. This type of configuration helps accelerate boot and application load times when compared to performing the same operations from a hard drive
However, only a fraction of the OS and application files are actually needed during loading. Many users install at least 80GB or 120GB SSDs in order to accommodate their software, but the actual capacity needed for these loading operations is considerably smaller. People often pay far more per gigabyte than is necessary just to achieve their acceleration goals.
A more moderate approach involves a smaller version of the conventional SSD using the mini-SATA (mSATA) port rather than the conventional SATA interface. In appearance, mSATA looks like a conventional mini-PCI Express connection, but it uses different electrical signaling in order to communicate with the system’s SATA controller. Intel released its first mSATA-based part (SSD 311Series) in May 2011. This 34nm SLC product was replaced in April 2012 by the 25nm SLC-based 313 Series, which in turn gave way to the 6Gb/s 525 Series in January 2013. All of these leverage Intel’s Smart Response Technology (SRT), a software-based caching technology released in 2011 for the Z68 chipset. SRT is contained in Intel Rapid Storage Technology 10.5 or later. The BIOS must have the drive set to RAID mode, and up to 64 GB of mSATA storage can be allocated for caching. Similar yet competing caching schemes exist for mSATA drives, but Intel is by far the most prevalent in the consumer market.
Samsung 256GB MZ-MPC2560 mSATA drive.