Why Speed and Capacity Matter for Hard Drives

One of the reasons for choosing a desktop computer is the ability to install large amounts of storage. The combination of multiple drive bays and easy expandability is a sure winner for anyone looking for large amounts of storage capacity.

What Makes a Hard Drive Fast?

While no internal hard drive is fast in comparison to an SSD, there are some that are definitely faster than others, and when you want to combine size and speed there are few better options than a large fast hard drive. You just can't easily get the same capacity from solid state, even if it is faster than SATA with a 16 MB cache. When looking for a fast drive, consider the following features:

  • Interface: Most modern drives feature a SATA interface, which in the SATA III revision offers up to 600 MBps transfer rates. Faster interfaces make for faster hard drives, and the switch to a serial interface with SATA made for a huge difference in hard disk performance.
  • Rotational Speed: The higher the rotational speed, the faster the platters move past the heads and the higher the maximum sustained transfer rate.

How Should You Choose?

Choosing a new hard drive can be difficult, especially when you look at all the different specifications. One thing most people can agree on is that a 7200 RPM SATA desktop HDD is a good choice to start with. The original SATA specification offered transfer rates of 150 MBps, but SATA III has increased that by a factor of four, giving it more than enough bandwidth for many SSDs. There are a few points beyond that which you should consider when looking for a new SATA III 7200 RPM hard drive:

  • Cache: Look for a drive with at least a 32 MB cache; the more cache your drive has the faster it can respond to requests. It's also easier to make use of the full bandwidth of your SATA connection if you are reading from cache. If possible, look for a 64 MB cache or more to increase responsiveness.
  • Capacity: One advantage of the SATA III standard is that it enabled 4 TB and larger drives; the faster a drive can transfer data, the more capacity you can make use of in a timely fashion.
  • Form Factor: For desktops, you can usually get more from a 3.5-inch drive than a 2.5-inch drive. The advantage is that the larger platters have a higher edge velocity so more data passes under the heads in a given amount of time.

Making Use of Storage Space

Just as the shift from single-core to dual-core processors greatly increased the flexibility of computers for multi-tasking, the move to high speed SATA III drives with 32 and 64 MB caches increased the ability to both store and retrieve data. SATA was a boon for a lot of users because it made drives that much faster.