Despite what some voices in technology media say, if you’re waiting for parity in the SSD vs HDD price war, it could be quite a while—even though we have watched SSD pricing decline steadily for the past year. Currently, the most inexpensive SSDs hover around $0.30 per GB—a pretty good deal, but when HDD prices are something like $0.04 per GB and also on the decline, waiting for price parity does a disservice to both technologies.
This is because the technology behind SSDs and HDDs make them suited for different tasks. Measuring both types of disks using the price per GB metric is essentially a useless way to compare them.
Hard drives spin magnetized disks and they can be noisy, slow, and hot. But they also offer vast amounts of storage capacity. If you need to store a massive amount of data, you could use several large SSDs or one HDD. For instance, Seagate offers a non-enterprise 6 TB 3.5-inch hard drive (STBD6000100) for desktop systems. As for datacenters, they still largely rely on hard drives with a few exceptions, most notably Facebook, which has had reliability issues with all-flash arrays.
Solid state drives on the other hand utilize no moving parts, just a ton of floating gate transistors. No moving parts mean no heat and no noise. Incidentally that enables them to retrieve and store data much quicker than hard drives. Those benefits alone are enough for people to use solid state drives as main storage drives to run operating systems and frequently used applications. Here, something like the 500 GB Samsung 850 EVO SSD features enough storage capacity for most everyday tasks, with speeds far exceeding high-RPM spinning drives.
Based on performance alone, most power users would choose the solid state drive for the operating system and frequently used programs, with the hard drive for documents and media. For some system builds, a hard drive might not even be included—just a singular SSD. But though hard drives may be on their way out as primary storage volumes, they continue to serve well for mass storage and data backup for the foreseeable future.
A similar thing happened to tape backup media. Datacenters still use tape formats such as Linear Tape Open (LTO) for storage despite the fact that they’ve been outclassed by other storage types. Slow as LTO storage is, it works great for archival purposes. It sticks around because it fills a unique niche, just like how hard drives may fill another niche in the future.
Even when comparing different SSDs, price/GB shouldn’t be the main focus. Performance and reliability factors should drive the purchasing decision. If the faster and more reliable drive happens to have the lowest price per GB, then great. In my opinion, higher read-writes and a reputation for reliability are worth the extra few cents per GB just for peace of mind.
In any case waiting for price parity with SSDs and HDDs is nothing more than a distraction. For one, it is a long time off before we understand the long-term reliability of flash storage. More importantly, it undercuts the best use scenarios for both HDD and SSD technologies on which system builders should have a grasp.