Hard Drives

Sideways view of a hard drive. The hard drive is the main storage space of all modern computers. It is the place that the Operating System and all other programs and software are stored until they are needed by the computer. It is also the place where data is stored for later use. Most standard commercial hard drives that come pre-installed in computers are what is known as an IDE or EIDE hard drive. These drives are supported by RedHat Linux 5.2.

SCSI hard drives are less common, and while they are faster, their controller cards are not always compatible with Linux. For a small webserver or Internet node, there is no need for a fancy SCSI drive. If the computer that is being configured for Linux already has a SCSI hard drive inside it, make certain that the card inside the computer that is connected to it is listed on the supported hardware page.

For both types of hard drives, bigger is certainly better. For a typical installation, there should be at least 250 Megs of space on the hard drive, and email, graphics, and programs will take up remarkably large amounts of space. The space they require will grow over time as they are used. However, because Linux was written before large hard drives were common, any drive larger than 2.1 Gigabytes will require some special configuration during the installation of Linux onto the computer. To configure these hard drives to work correctly, the Linux OS needs to know some things about how large they are, and how to access them.

Different types of data may be stored on a hard drive, but the method of storing all of this data remains the same from file to file. Each hard drive consists of a series of metallic disks, carefully balanced so that they can be read by a magnetic "finger" in much the same fashion as a record player reads data off a record. The location of the data is stored in a portion of the computer's memory, and is written out in terms of "heads," "cylinders," and "tracks." To operate the hard drive correctly, Linux needs to know how many heads, cylinders, and tracks there are inside a hard drive.

Topdown view of a hard drive disk. If the hard drive in the computer was installed after the computer was shipped from the factory, the person who installed the hard drive may have the manuals that came with the hard drive. These manuals will also contain information about the number of heads, cylinders, and tracks. Otherwise, most corporations maintain web sites with the specs of the hardware they sell. A web search on the model and make of the hard drive inside the computer should yield the necessary data.

Here are the specs on the hard drive Ariel is currently running off of:

Western Digital Hard Drive
3.5 inch enhanced IDE [EIDE]
Drive Size: 3.1 GB
Cylinders: 6136
Heads: 16
Sectors/Track: 63
Actual Capacity: 3166.7 MB

When installing Linux on the computer, after booting from the boot diskette, there will be a prompt for the installer. Hitting [Enter] at this point in time will simply begin installing Linux. However, for a large hard drive, type:

linux hda=number of cylinders, number of heads, number of tracks
instead of just hitting [Enter]. This tells the installer that the hard drive located at hda has a hard drive with those specifics, and from the installer will extrapolate from that data how large the hard drive is. Simply hitting [Enter] with a large drive will tell the installer to install to a 2.1 Gig hard drive, regardless of its larger size.

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Created: February 14, 1999
Last updated: May 13, 1999