How To Build A PC: From Component Selection To Installation

Step 6: Select Storage

Choosing internal mass storage once meant deciding between the performance of a solid-state drive (SSD), the capacity of a mechanical hard drive (HDD), or the greater expense of both. But as with system memory, advancements in manufacturing and maturing technology put medium-capacity SSDs within reach for most enthusiasts. We're even seeing 256 GB drives under $100. That SSD might not make processing-bound workloads run faster, but they'll certainly launch quicker, access the data they need more expediently, and respond in a way you simply won't experience with a hard drive.

Of course, you'd still need a handful of high-capacity SSDs if you were planning on storing your photo, movie, and game collections on solid-state storage. Fortunately, adding the expense of a 1 TB disk for under $60 makes the combination of just-right SSD and big hard drive more palatable.

The flash-based capacity you'll want depends on what you do with your PC. A Windows installation rarely exceeds 32 GB without additional programs installed, even after many months of collecting temp files, cookies, and other "temporary" trash. Popularly-used apps like the Office suite and Adobe's Creative Cloud software can easily consume many times that much space, and games regularly eat up more than 10 GB each all on their own. Most of us could squeeze Windows and essential programs into a 128 GB SSD without much effort, but 256 GB drives are the sweet spot if you're adding a few games, too.

Mechanical storage becomes critical once you start piling on years of pictures, music, and movies. DVD and Blu-ray disc images consume up to 8.4 and 50 GB, respectively. If you love to archive video, your capacity needs will expand very fast this way. Game install packages can be even larger than the games themselves, and those of us with less-than-perfect Internet access are reluctant to delete source data, even when installation finishes.

Although SATA is the most popular desktop storage interface, other drive form factors are becoming more popular. Among them, mSATA is both widely available and mature. Designed to install onto a motherboard, these have become so common that some companies produce adapters to install mSATA drives into 2.5” bays using standard SATA data and power cables.

Beyond mSATA, we're also starting to see M.2- and SATA Express-capable platforms. They're still not very common, but because they both enable PCI Express-based transfers, the performance of future storage products will outstrip today's SATA 6Gb/s drives. As a reminder, just one PCI Express 2.0 lane gives you up to 500 MB/s of bidirectional throughput. A two-lane link should be theoretically capable of 1 GB/s. Meanwhile, SATA 6Gb/s is rated for up to 600 MB/s, though a more practical ceiling is in the 550 MB/s range.

Though most systems use either one large drive or a combination (a smaller SSD and larger hard drive, for example), other configuration options let you choose between additional performance, more capacity, increased data security, or a combination of these.

RAID stands for Redundant Array of Inexpensive Disks, a group of methods that allows data to be spread across several drives concurrently. Most enthusiast-class motherboards support at least RAID modes 0, 1, 0+1, and 5. Each array of disks appears to be a single disk to programs other than the RAID utility.

The possible use of RAID affects the number and capacity of drives selected, so a very brief description of these modes is in order:

  • Level 0 divides data into chunks that are spread across two or more drives at the same time, providing up to double the transfer rate (in the case of a two-drive config) and the combined capacity. Because of the way the data is divided, this mode is also referred to as "striping" by in-the-know storage gurus. The major drawback is that if a member drive fails, the array's data is lost.
  • Level 1 mirrors two or more drives so that if one fails, data can be recovered from the other. The major drawback is that because both drives (again, in a two-drive array) store the same data, available capacity doesn't increase.
  • RAID 0+1 allows four (or more) drives to be set up as a "mirrored" set of "striped" drives. In other words, it's a RAID 1 array composed of two RAID 0 arrays. If one striped set (RAID 0 array) fails, data can be retrieved from the other. Total capacity is still limited to that of one striped set.
  • RAID 5 creates parity bits for data recovery. Data and parity bits are distributed across all drives, increasing transfer rate, while sacrificing only the amount of space required to store the added parity bits (the capacity of one drive in the set).

Generating parity bits for RAID 5 requires processing, which means that RAID 5 enabled in software can hog resources. Conversely, RAID Levels 0 and 1 generate little CPU overhead. Gamers with little regard for long-term data storage may choose Level 0 for performance, and anyone with a significant amount of valuable data may choose Level 1.

Tom's Hardware continuously reviews drives and storage controllers, with several of these articles going into additional detail concerning RAID modes, benefits and consequences.