Glossary of Western Digital Hard Disk Drive (Letter J,K,L)

jumper
An electrically-conductive component placed over pairs of pins extending from the circuit board on the hard drive jumper block to connect them electronically. Jumper placement is one method of designating a hard drive as Master or Slave.

KB
Kilobyte. Usually, this is a unit of 1000 bytes. In computer memory, which is partitioned into sizes that are a power of 2, a kilobyte is equal to 210 or 1024 bytes.

LAN
Local area network. A system in which computer users in the same company or organization are linked to each other and often to centrally-stored collections of data in LAN servers.

landing zone
A location on the inner part of a disk to which heads move when commanded or when powered off. User data is not stored in the landing zone.

laser textured media
A treatment that minimizes friction and wear on a hard drive. The precision and consistency of this process contributes to the robustness of WD drives.

latency
The period of time that read/write heads wait for a disk to rotate to the correct position for accessing requested data. For a disk rotating at 5200 RPM, average latency is 5.8 milliseconds (one-half the revolution period).

LBA
Logical block addressing. A method of addressing sectors on a drive as a single group of logical block numbers rather than cylinder, head, and sector addressing (CHS). LBA allows accessing larger drives than is normally possible with CHS addressing.

LED
Light Emitting Diode. An electronic device that lights up when electricity is passed through it.

logical address
A storage address, which may not describe the physical location, for requesting data retrieval. A controller converts a request from a logical to a physical address and is able to retrieve data.

logical drive
A section of a hard disk that appears to be a separate drive in a directory structure. Up to 23 logical drives can be created on an extended partition of a hard disk, using letters A-Z with three reserved: A and B for diskette drives, and C for the first primary DOS partition. Logical drives are commonly used for group directories and files.

low-level formatting
A process, also called initialization, that prepares a hard drive to store data. Low-level formatting sets up the locations of sectors so that user data can be stored in them. Low-level formatting is performed at the WD factory; users need not perform low-level formatting on a WD drive.

LUL
See Ramp Load/Unload

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System BIOS and Hard Drive Related FAQs (Part I)

System BIOS The most commonly asked questions about the system BIOS and its relationship to hard drives. The following will provide you with basic information beginning with the definition of a BIOS, to identifying key features found in various BIOS’s. The purpose of this document is to aid you in solving minor difficulties you may be currently experiencing.

1. What is Logical Block Addressing (LBA)?

LBA is a mathematical scheme for addressing sectors, beginning at cylinder 0, head 0 and sector 1, which is equal to LBA 1. This scheme linearly maps the drive until the final physical sector is reached. LBA is efficient because it reduces some system overhead by not having to convert the operating system’s LBA to the BIOS CHS and then back to drive LBA.

2. What is CHS?

CHS stands for Cylinders, Heads and Sectors, this is the conventional means for BIOS to communicate to the drive. CHS has a limitation of 1,024 cylinders, 16 heads and 63 sectors per track resulting in a maximum capacity of 504 MB.

3. What is the difference between Normal, LBA or Large mode?

Normal mode is the standard BIOS translation scheme. This mode does not support drives greater than 504 MB. Large mode is a generic translation scheme used by some BIOS’s to access drives up to 1 GB. Logical Block Addressing (LBA) mode is a more advanced method of translation than Large mode. LBA mode is a somewhat faster and can see drives up to 8 GB.

4. What if the BIOS does not support the full capacity of the drive?

There are three possible answers to this question:

  • Upgrade the BIOS for the computers motherboard or replace the motherboard.
  • Add an Enhanced IDE card that has its own BIOS that provides support for large hard drives.
  • Install a translation software product such as Maxtor’s MaxBlast software, they’re latest version is 9.06M.
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Locate CHS values for older Seagate, Maxtor, or Quantum ATA drive?

What are the Cylinder, Head and Sector values [C/H/S] for ATA disk drive and how to find them?

C/H/S is an older method of identifying drive capacity and tracking the location of data on the drive. The C/H/S method was replaced with the Logical Block Addressing (LBA) when drives transitioned above 8.4 GBytes. If you are attempting to use a drive smaller than 8.4 GBytes then the C/H/S information can be found by searching the Product Finder in the bottom left corner of the Seagate support site.

For drives larger than 8.4GB it is recommended that the BIOS be allowed to automatically negotiate with the drive using the LBA method.

Note: Changing the C/H/S setting in the BIOS can make existing data on a drive unreadable.

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What is Logical Block Addressing (LBA)?

Logical Block Addressing (LBA) is a mathematical scheme for addressing sectors, beginning at cylinder 0, head 0 and sector 1, which is equal to LBA 1. This scheme linearly maps the drive until the final physical sector is reached. LBA is efficient because it reduces some system overhead by not having to convert the operating system’s LBA to the BIOS CHS and then back to drive LBA.

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