Storage (Hard Drive, SSD) Buying Guide
1. What is a hard drive?
If you are reading this article, then you probably already know the answer to the question. But in case you’ve been living under a rock for the past couple decades; a hard drive is where all the information on your computer is permanently stored until it’s given specific commands to delete them. Whether it be your operating system or the picture of you at the Halloween party, you’ll find it on your hard drive.
2. Mechanical vs Solid State Drives
Most of today’s hard drives¹ come in two forms: mechanical and solid state. Each has their own pros and cons and we’ll discuss more about them below.
Mechanical drives are geared towards consumers looking for a mix of value and practicality. You can easily find a 2 terabyte hard drive today for less than $150². With their massive capacity and appealing price tags, they are the ultimate balance between functionality and cost in the storage world.
With that being said, however, mechanical drives are not without flaws. The foremost being their inability to resist against physical damage. Because there are many moving parts within a mechanical drive, they are very prone to breaking from vibrations and impact. Another problem with mechanical drives is that they generate a lot of heat, and is loud when data is being accessed (ever wondered what that <GURCH GURCH> sound is whenever you launch Skyrim?).
How they work
The inside of a mechanical drive consists of one or more rotating plates, called platters. This is where the data gets written, stored, or deleted. A moving arm, called the actuator arm, writes or deletes data on the platters.
Summary: Mechanical drives
-Slow compared to SSDs
-Moving parts: physically susceptible to damage (sudden impact, vibration, etc)
Solid State Drives (SSDs)
Created for enthusiasts who crave for the highest level of performance, SSDs are the undisputed speed demons of the storage world. Without having to wait for the actuate arm to read the data off of the platters and instead directly transfer data from the NAND flash memory, SSDs feature 3x or more read and write speeds of traditional mechanical drives. These (relatively) new comers in the market are setting out to overtake the hard drive market.
Featuring no moving parts, solid state drives can take punishment much better than their predecessor. Vibration and impact no longer affect their operation. They use half, or sometimes even a third of the power required to operate mechanical drives, again thanks to the lack of moving parts. Due to this decreased power draw, they also output less heat than mechanical drives. This directly translates to longevity of the components.
So why are we still gripping on to mechanical drives when SSDs seem like an infinitely better alternative? Just like mechanical drives, SSDs are not flawless. Currently, their biggest problem is their capacity. Due to the high costs of NAND flash memory, the size of SSDs must be limited to what the consumers can afford. Manufacturers are not unable to produce gargantuan-sized SSDs, as their prices would be stratospheric.
Another problem is that SSDs have a more limited lifespan. NAND flash memory only allows for a certain number of read / write cycles before failing or becoming unusable. But if you are worrying about whether or not your newly-bought SSD will last you till next week, fear not as the controller on the drives will minimize the amount of read / writes by compressing data during operation and will do its best to make the limited number of read / write cycles last you for years to come.
How they work
A component hard wired into the SSD called the controller monitors the flow of data entering and leaving the drive and acts as the bridge between the drive and the computer. The controller also has a number of other useful functions, such as encryption, garbage collecting, and error correction.
Summary: Solid State Drives
-Less power draw, less heat output
-Limited R/W cycles could pose a problem
3. What to look for when purchasing drives
Spin rate – The speed of a mechanical drive is mostly dictated by its spin rate (measured in RPM, which stands for rotations per minute). The higher the RPM, the less time the actuator arm will have to wait to read a specific sector. Today’s mechanical drives typically come in 5400RPM, 7200RPM, and, in a more rare form, 10,000RPM.
Cache – Mechanical hard drives usually come with a small amount of very fast memory, called cache, to store the most-used instructions and data. Theoretically, the larger the cache size the faster the drive. But the difference between a drive with 64MB cache and a drive with 32MB cache with similar RPM is marginal.
Controller: The current SSD controller market is currently dominated by two contenders: Sandforce SF-2281 and Marvell 9174, with the SF-2281 being hailed as the performance champ.
Go with brand names
Not only do well known manufacturers use high quality components for their drives, they also often come with an extended warranty. Some major companies are: Intel, OCZ, Patriot, Western Digital, Seagate, Corsair. Also take note of the warranty on both hard drives and SSDs. Try to purchase from companies who actually stand behind their products for more than 1 year.
The current generation of motherboards typically come with either SATA 2 3Gb/sec or SATA 3 6Gb/s ports. SATA2 3Gb/s ports have a maximum bandwidth of 300 MegaBytes/second while SATA 3 6Gb/s ports have a maximum bandwidth of 600 MegaBytes/second. While it is possible to connect SATA 3 6Gb/s drives to SATA 2 3Gb/s ports, to unleash the full potential of the SATA 3 6Gb/s drives, make sure to connect them to the SATA 3 6Gb/s ports.
As the old saying goes: “you get what you pay for”. This couldn’t be more true for hard drives. If you absolutely need performance, get an SSD. Otherwise, a mechanical drive will serve your just fine.
¹ Solid State Drives are NOT hard drives; however, we are going to refer to them as hard drives for the purposes of this guide. The word “hard drive” only refers to traditional hard drives, not solid state drives. Solid state drives are solid state drives.
² At the time of writing, mechanical drives have spiked in price due to the flood in Thailand. The current drive market is unstable, and hard drive production isn’t expected to return to normal until Q4 2012.