Internal Hard Drive Buying Guide
Table of contents
The internal hard drive is a data storage device installed and used in desktop PCs, workstations, and servers, as well as certain consumer electronic products (these mainly use small form factor internal hard drives) such as digital cameras and digital audio/video players. Internal hard drives provide massive storage capacities for all types of data including images, documents, movies, music, games. This means more fun for you and greater functionality for your computer and devices!
This type of storage device is non-volatile, meaning that it does not require constant power to maintain data. Inside the internal hard drive, there are one or several platters for data storage and read/write heads used to access or record data. A set of components drives the platters and the heads perform data operations on the platters as they spin. The internal hard drive uses a mechanical design, which is markedly different from the other popular permanent storage solution: Flash Memory.
Nearly all storage applications on the desktop PC can be classified as personal storage. Personal storage applications do not require the hard drive to work non-stop, meaning they make fewer read/write operations. Most personal storage applications don’t require extreme performance, but high reliability is still a necessary trait.
The consumer electronics domain is an exciting new playing ground for internal hard drives because digital cameras and digital audio/video players are constantly throwing up new requirements balancing increased capacity and cost, which is what the internal hard drive does best. Since most consumer electronic devices try to be as small as possible, fitting the standard 3.5” hard drive has proven unfeasible. Manufacturers have opted to use the much smaller “Microdrive” instead.
Enterprise applications are closely related to workstations and servers, for example, CAD/CAM, digital video editing and production, as well as database. Enterprise storage applications have higher performance and reliability requirements than other applications, and the hard drive workload is very heavy. Server hard drives are expected to run normally without the slightest interruption 24 hours a day, 7 days a week.
There are several form factors to ensure the compatibility of the internal hard drive with a variety of different devices.
Data storage capacity is becoming more and more important for internal hard drives with the increasing size of operating systems, programs, games and multimedia. Currently, the Operating System, 3D games and high definition videos each require several GBs of storage. 3.5-inch internal hard drives can provide over 500GB. The 2.5 inch form factor has reached 160GB. Even the tiny 1.0-inch hard drive has reached the amazing capacity of 8GB. We can expect capacities to keep climbing in the future, too.
Car owners are no strangers to the term RPM (revolutions per minute). It is an index used to measure the rotational speed of engines. The spindle inside the hard drive and its RPM are closely related to the drive’s performance. Higher RPM means less time is spent accessing stored data for greater performance. Performance-sensitive enterprise storage applications generally use 10,000~15,000 RPM internal hard drives, while personal applications are well-served by 7200 RPM products.
The cache refers to high-speed RAM (random access memory) integrated on the PCB of a hard drive. Cache is used as buffer among the CPU, memory and hard drive. Drives with more cache generally perform at a higher level than drives with less. Cache sizes of 2MB, 8MB and 16MB are currently standard options for 2.5-inch and 3.5-inch internal hard drives, while 1.0-inch products may only be equipped with 128KB.
The interface is used to connect the hard drive with the computer. Here we list the most commonly used interfaces.
Filter by Application and Interface
As we found out in the Applications Overview section, there are three types of internal hard drive application: Enterprise storage, Personal storage, and Consumer electronics. Based on the obvious differences between the applications, you can easily decide what type of interface you need for your internal hard drive.
If you are building a brand new system, it is recommended that you choose either SAS for Enterprise storage or SATA for Personal storage as a means of future-proofing your new system. If you are simply adding new hard drive(s) to your current system, please check the type of interface provided by your motherboard.
Moving on to Performance
Spindle RPM is the main factor related to the performance of a hard drive. Though there are many speed options, there is actually some relation between RPM and the interface.
The above table lists the mainstream relationship between interface and RPM. Higher RPMs reduce access and write times of a hard drive, and is one of the areas in which internal hard drives are rapidly improving. 10,000 RPM hard drives using the SATA interface have already begun to appear in the market for personal storage applications, but tend to cost more than their 7200RPM counterparts.
Although higher capacities tend to sound appealing, it can sometimes result in per unit storage cost increases instead.
1. Hard drive A is priced at $103, and offers 250GB storage. The cost per GB storage of this hard drive is $0.412/GB ($103/250GB).
2. Hard drive B is priced at $330, and offers 500GB storage. The cost per GB storage of hard drive B is $0.66/GB.
Like RPM, a larger cache size is better for performance. Currently, 8MB and 16MB cache is mainstream configuration for 3.5-inch and 2.5-inch internal hard drives, while 128KB is more common on 1.0-inch internal hard drives. A larger cache tends to cost more, however.