Hard Drives

– Part Two

How big should your hard drive be?  As we saw in the previous article, the file system your computer uses can determine the maximum size, but if you are using Windows XP and the NTFS file system the sky is the limit (almost).

Modern hard drives are measured in Gigabytes (GB).  As hard drive technology advances capacities increase and prices come down.  Just last year it was common to see standard computer systems with a 40 GB hard drive.  Now we are more likely to see 80 GB drives installed in any department store computer. 

That's a lot of space!  The Windows XP operating system takes about 4 GB of hard drive space, so why would anyone need another 70 or so GB?

Part of the space on a hard drive is used to store computer programs.  Computer applications are getting bigger every year.  They are still commonly released on CDs (which have a capacity of 700 MB) but many of the latest releases come on DVDs (with a capacity of 4.7 GB).

So – programs are getting bigger and require more hard disk space.  Another use of hard disk space is for storage of entertainment files such as music and movies.  Sure - music files can be compressed by converting them to MP3 and video files can also be compressed, but a typical 90 minute movie still takes up about 700 MB of space.

Compression is used to reduce file sizes.  The trouble with most compression methods is that some of the original data is discarded.  Hard core music and movie fans don't like the loss of quality that is associated with compression and insist on original quality files.  The cost?  A movie typically takes about 4.5 GB and 10 minutes of uncompressed music takes about 10 MB.

A few movies and a few albums and your hard drive space is gone!

Types of Hard Drives

Go shopping for a new hard drive and you will be presented with a confusing spectrum of varieties.  EIDE, SCSI, ATA, IDE, SATA, FireWire, and USB are some of the types you will see.  All of these refer to the interface that connects the hard drive to the motherboard, so knowing what type of interface your motherboard supports is essential.

The most popular type of drive up until recently was EIDE but it is being replaced by SATA. EIDE (Enhanced Integrated Drive Electronics) is actually the same as ATA, so any motherboard that supports ATA also supports EIDE and IDE. The hard drive is connected to the motherboard with a Parallel Interface.  The performance on these drives is greatly enhanced if they can use DMA (Direct Memory Access) to give the hard drive direct access to memory.

The new standard for hard drives is SATA (Serial ATA) that provides faster data transfer and more convenience than EIDE.  EIDE drives had to be configured in a Master/Slave configuration which meant that only two drives could be connected per channel. SATA does not have this limitation, and SATA drives can also be 'hot-swapped' - removed from the computer while it is running.

SCSI is another efficient interface, but SCSI drives never gained much popularity in the home PC market and remain fairly expensive when compared to SATA.

Buying a Hard Drive

If you are in the market for a new hard drive, you have to know what kind of drive your motherboard supports (SCSI, EIDE etc.) and the type of the file system your operating system uses.

Assuming you have Microsoft Windows XP installed on your computer, you should probably look for either an EIDE or SATA drive.  Most modern hard drives give excellent performance and speed, so it's hard to go wrong with almost any drive.  Prices are very reasonable -- a 250 GB SATA drive will set you back about $150.

You can either replace your existing hard drive or add a second (or third or fourth).  Adding extra drives is much easier than replacing an existing drive because you don't have to go through the inconvenience of reinstalling the operating system.  All your original files and programs will remain intact and you will have plenty of new storage space.