Computer Hard Drive

The Computer Hard Drive is our long term memory. It is slow but compensates by offering enormous capacity. Hard Drive technology have stayed basically the same since its introduction in 1956 by IBM. It is still spinning magnetic disks (platters) with an arm and a head that reads and writes information onto the disks. See picture below:

computer hard drive

The big change have been made in the density of the platters, i.e. we can store more on the same size platters. Other improvements have been made in transfer rate and access time. One of the disadvantages of the Hard Drive is that it is not very reliable. Computer Hard Drive failures are not uncommon and you should always back-up your data. Lately Hard Drives based on flash memory, Solid State Drives or SSD, have emerged as an alternative. However, they are still very expensive and mostly found in UMPCs and high-end laptops. The reliability and access times though are much better. A SSD is about 50% faster than a traditional Hard Drive.

In my past two Systems I have added a second drive, which has been a life saver. You never know what is going to happen and that back-up drive can be a savior. Preferably a SSD, but any small and inexpensive Hard Drive of good quality will do.

As with all other components that connects directly to the Motherboard, the Hard Drive has a specific interface. There are several interfaces available, but for a desktop computer only two are relevant, SATA and PATA (IDE). Almost all Motherboards now feature SATA exclusively for the Computer Hard Drive. The PATA interface on the Motherboard is for the DVD. SATA comes in two versions SATA (SATA 1.5Gbit/s) and SATA2 (SATA 3.0 Gbit/s). SATA and SATA2 interfaces are compatible and on some Hard Drives there is a switch to change between the interfaces. I recommend that you use the same interface and don't mix SATA with SATA2.

Computer Hard Drives are also available in several Form Factors, just like the Motherboard. Hard Drives for Desktop computers come in only one Form Factor, 3.5'. For Laptops and UMPCs smaller Form Factors are available, for example 2.5' and 1.8'. Even DAPs, think iPod, have miniature Hard Drives inside.

Many Motherboards now also features RAID (Redundant Array of Inexpensive Disks). The idea with RAID is to increase performance and reliability. If you have installed two or more Hard Drives then to put them in an RAID array can be beneficial. There are many different RAID Levels. For example RAID 1 is basically two Hard Drives where one Hard Drive mirrors the other one. The thing is that the OS will see the two Hard Drives as one (as will you). RAID is a complex subject and if you are interested I recommend you make a web search to find out more.

How to choose a Hard Drive

For a Budget system Capacity will be the most important. The more expensive your system, the more attention you have to pay to the other details. Spindle Speed and Cache are more important than Capacity in a Gaming rig. A large Cache improves access times and so does Spindle Speed. If you can afford it go for a SSD. It is also advisable to buy two Computer Hard Drives, one exclusively used for back-up. Only skimp on a second Hard Drive if your on a seriously tight budget. A small but good quality Hard Drive will not set you back more than US$50, definitely cheaper than the time and money you need to spend to recover lost data. And remember to double check the interface, SATA or SATA2, and the Form Factor. I also recommend buy a retail Hard Drive, because they will offer up to 5 years of warranty, which the OEM will not.

Brands

Throughout the years several Hard Drive manufacturers have trown in the towel. The brands below are basically the ones that are left. And it will not get easier. As prices for SSD is falling, the attractiveness of a spinning platters becomes less and less with every passing month. The SSD market, however, is not mature yet and no reliable brands can be identified at this moment.

Hitachi
Western Digital
Seagate
Samsung
Fujitsu

Technicals

The Computer Hard Drive is not very technical but a few insights into the inner workings of a Hard Drive can go a long way.

Capacity: This tells us how much we can store onto the Hard Drive. More is not always better, because the Spindle Speed and Cache affect performance, not Capacity.

Spindle Speed: This is the speed by which the platters are spinning. The faster they are spinning the better the access time and the faster your computer will seem to go.

Cache: This is the working memory of the Hard Drive. The larger the Cache the faster the access time.

Average latency: These numbers are pretty much the same from all manufacturers. The lower the better.

S.M.A.R.T: S.M.A.R.T (Self-Monitoring, Analysis, and Reporting Technology) is checking your Hard Drive for errors and predicts failure. Use a free software like SpeedFan to have access to S.M.A.R.T. In this way you can replace the failing Hard Drive before you lose all your data.

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