Hard Drives (continued...)

Drive Types
Drive types are categorized by their interface with the motherboard. The most common type of HD you'll find in most PCs is the IDE (Integrated Drive Electronics), or one of its current variations. Previous to the IDE, hard drives had to be connected to the computer via a controller card. This card was inserted into one of the ISA slots on the motherboard and 2 different ribbon cables were attached to the drive.

One cable was the controller cable, transferring control information to the hard drive, relaying information from the BIOS, telling the drive which sectors to position its heads over and when to read or write. The other was the data cable, which transferred data to and from the drive.

The most notable improvement the IDE offered, was moving the controller circuitry right onto the drive itself. The drive was attached to an interface card (sometimes called a 'paddle board') which was nothing more that a direct connection to the ISA bus. Often the connector for the IDE was on the same interface which provided controller circuitry for the floppy drive, joystick port, serial and parallel ports.

Also labeled the ATA (Advanced Technology Attachment), the IDE bus can only support 2 drives. By setting jumpers on the drive itself, one is designated 'master' and the other 'slave'. This prevents conflicting controller information by disabling the controller on the 'slave' drive, and using the controller circuitry on the 'master' for both drives. Until IDE was actually standardized, manufacturers often came up with their own enhancements and versions which sometimes created compatibility problems when trying to hook up more than one drive. Because ATA conformed to the same standards that the BIOS did at the time, storage space was limited to 528 MB.

The standard was not limited to hard drives, however, it was discovered to be an excellent interface for other storage devices, such as tape drives and CD-ROMs.

Of course, enhancements and improvements are always being discovered, that's how standards change. An improved version of the IDE is the EIDE (Extended Integrated Drive Electronics). EIDE overcame the 528 MB barrier with LBA (Logical Block Addressing). If the BIOS supports it, the hard drive's controller sends back a long list of logical addresses, each representing a single sector on the drive.

The problem is, the BIOS must remain backwards compatible with legacy devices. It has to be able to translate the long list of logical address blocks to and from the CHS (cylinders, heads, sectors/track) translation method. Having to remain backwards compatible has always been the anchor slowing down many of the advancements in computer technology.

The EIDE technology is much more efficient using the newer 32-bit bus (as opposed to the 16-bit ISA), and the 40-pin connectors for the ribbon cable have been integrated right onto most current motherboards. EIDE supports up to 4 devices. This is done by using 2 separate channels, primary and secondary, each of which can support 2 devices designated 'master' and 'slave'.

EIDE, also called Fast ATA-2, makes use of Direct Memory Access (DMA) which allows a drive to write directly to memory, bypassing the CPU.

Further developments to the IDE include:

ATA-4 (UDMA33), which uses 3 synchronous DMA channels that doubles the performance of EIDE from 16.5 MB/Sec to 33 MB/Sec.

ATA-5 (UDMA66), which uses a special data cable and allows for 66 MB/Sec.

To use these two modes, your drive, your BIOS, and the connection to the motherboard all must conform to the standard. If they don't, the drives will still act as typical EIDE devices.

Partitioning
The process of creating two or more smaller storage areas on a hard drive that function like separate hard drives (virtual drives).

Makes storing and retrieving information on hard drives more manageable.

Cluster size is a function of the partition size. The bigger the partition, the bigger the cluster size resulting in more wasted space. (Using the FAT file system, a cluster is the smallest allocation unit available. Any remaining space in a cluster after a file is saved goes unused).

A single-partitioned drive can waste up to 40% of its space with unfilled clusters, depending on the sizes of the files stored.

Maintenance
-Be aware of file management and organization.

-Maintain a regular schedule of deleting .TMP, .CHK, .$$$, .BAK files and temporary internet files, as well as removing unwanted programs and files.

-Use a scanning utility to check for, and repair, cross-linked files, lost clusters or bad sectors on a monthly basis. Microsoft provides a utility called Scandisk with DOS and Windows that does a good job of this. Just type SCANDISK at the DOS prompt, or choose it from the System Tools section in Windows95/98/2000.

-Defragment your hard drive periodically. As programs and files are removed from your hard drive and new ones added, they become defragmented, spread out on your hard drive in non-contiguous sectors. You may notice a decrease in the hard drive's performance, as the read/write heads have to jump all over the place trying to piece together files that are in scattered sectors. Again, your operating system may provide the answer. You can type DEFRAG at the DOS prompt, or choose Disk Defragmenter from System Tools.

-Always keep a copy of your drive settings from CMOS (its good to make a copy of all your CMOS settings).

-Develop a system of boot disks or recovery disks.

-Be careful of bumps, kicks, jolts and shakes. Remember the heads are very close to the disk surface, and if they touch (head crash) they can damage those sectors.

-BACKUP!

Informative Hard Drive Links ( Installation, setup, jumper settings, etc.)

Maxtor - http://www.maxtor.com/satisfaction

Fujitsu - http://www.fujitsu.co.jp/hypertext/hdd/drive/disk-e.html

Quantum - http://www.quantum.com/support/support.htm

Western Digital - http://www.wdc.com/service

Seagate/Conner - http://www.seagate.com/support/supporttop.shtml
Or http://www.seagate.com/toc.shtml

Samsung - http://www.samsung.com

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