Hard Drive Buying Guide
While your main concerns in purchasing a hard drive is the type and the means of connection, there are a number of other important features to look for.
Size does matter! It is amazing just how fast hard drives fill up with information over a short period of time. The general rule is purchase the largest hard drive you can afford. 60 GB should be considered the bare minimum on a single hard drive system. If you are adding on to your present system you can get by with a smaller sized one, say 20-40 GB, but you should still shoot for something larger.
The great thing is that hard drive prices have dropped dramatically over the last few years, so a good size drive is now easily affordable. Also, as sizes increase the price only goes up incrementally, so it can be very cost effective to buy larger.
Another important feature to look for is the hard drive's spin rate. This is a measure of how fast the platter is spun inside the drives casing. The faster the speed the quicker data can be read, written, and transferred.
With internal hard drives, the minimum acceptable speed is 5400 rpm. Some external and laptop drives run at speeds slightly slower, which is a fine tradeoff considering the value of portability. As with anything, the faster the spin rates the better for your system. Drives with speeds of spin rates of 7200 rpm (or more with SCSI) offer the finest data transfer rates and the smoothest system operations.
Cache is additional memory that acts as a buffer between the system and the drive. Frequently accessed data is stored in the cache for quick access. Cache sizes vary from 512 KB up to 16 MB on some SCSI drives. Again, the more cache you have on your drive the faster your drive will run.
A measure of how long it takes the hard drive to find a specific track on a disk. Speeds vary slightly from disk to disk, but you should always go for the faster drive.
Internal and External Transfer Rates
These rates tell how fast the drives actually read the data and pass it along to the system. The Internal Transfer Rate is how fast the heads can read data from the platter and pass it to the drive's cache. The External Transfer Rate (sometimes called the Transfer Rate or the Burst Transfer Rate) is how fast the heads can send the data from the cache all the way to the computer's memory.
Both of these measures give you a good idea about the expected speed of the hard drive. While there's little difference between operating speed from drive to drive, faster transfer rates equal better performance.
S.M.A.R.T. (Self-Monitoring Analysis and Reporting Technology)
A technology built into some drives that checks for potential problems during operation. This is a nice feature that can help alert you to some potential hardware problems. Be aware that your system's BIOS must support this function in order for it to work, although the drive will still work in a system without it.
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