Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Reexamination Certificate
2000-09-19
2004-07-13
Nguyen, Hiep T. (Department: 2187)
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
C711S170000
Reexamination Certificate
active
06763430
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to hard disk drives, and more particularly, to the optimization of hard disk drive performance.
2. Description of Background Information
Hard disk drives store information as magnetization patterns on magnetic media and are common components in today's personal computers. Typically, hard disk drives are the primary non-volatile storage location for both user data and software program data.
FIG. 1
is a diagram illustrating a conventional host computer system and its hard drive. Host computer system
12
includes fast access solid state memory
16
, computer system bus
20
, and CPU
18
. Memory
16
is a solid-state semiconductor memory such as a dynamic random access memory (DRAM) that stores the data being manipulated by CPU
18
. For example, memory
16
may store application code
22
, operating system code
24
, or user data
25
. CPU
18
and memory
16
communicate with one another over bus
20
.
Host computer
12
may read or write data from/to DRAM
16
to disk drive
10
. Head or write commands from host computer
12
are received and interpreted by controller
26
. Controller
26
controls spindle and actuator drivers
28
to read or write data to one or more magnetic platters in hard disk array (HDA)
30
.
Conventionally, hard disk drive
10
hides certain of its internal characteristics from the host
12
. For example, the physical layout of the disk's data tracks and the locations of defective data sectors are not known, and do not need to be known, by host
12
. Instead, host
12
, when reading or writing data with hard disk drive
10
, simply specifies an address for the data (called a logical block address), and controller
26
of disk drive
10
converts the logical address to a physical specification on the hard drive, such as the appropriate platter, track, and sector of the hard disk array
30
. Thus, host
12
may access the hard disk drive without having to concern itself with the internal characteristics of the hard disk drive. This can be beneficial as it allows hard disk drives to have different internal implementation as long as they present the correct interface to the host computer.
In certain situations, however, host computer
12
, by knowing the internal state of disk drive
10
, may be able to optimize commands to the disk drive. For example, if the host computer
12
knows how long it should take to execute each of a series of commands, the host computer may decide to first execute the one that will execute the fastest.
Additionally, if host computer
12
knows where the read heads of disk drive
10
will land when they are moved to the desired data track, the host computer may implement command reordering to reorganize a series of read commands so that they more efficiently coincide with the position of the read heads. In the absence of command reordering techniques, hard disk drive
10
executes commands in the order in which it receives them. The result is that the disk drive heads tend to randomly and inefficiently sweep over the surface of the hard disk platters. Command reordering techniques attempt to reorder the sequence of drive commands to minimize the random movement of the read/write head.
One way to implement techniques such as command reordering at the host computer level is to model physical parameters of the hard disk drive in the host computer and to optimize data requests to the hard drive based on the modeled physical parameters. Such a technique is discussed in U.S. Pat. No. 6,490,651, filed Mar. 14, 2000, and issued Dec. 3, 2002. This contents of this patent are hereby incorporated by reference.
In order to model the physical parameters of a hard disk drive, however, information about the basic physical characteristics of the hard drive, such as an accurate physical layout of the tracks and sectors on the drive, must first be gathered by the model. One way to gather such information is to have a skilled technician manually examine each disk drive. This method of gathering information, however, is labor intensive and is not suited for the general distribution of a generic disk drive model intended to model any disk drive.
Accordingly, there is a need in the art to be able to more efficiently gather information relating to the physical characteristics of a hard drive.
REFERENCES:
patent: 6237070 (2001-05-01), Ng
patent: 6253279 (2001-06-01), Ng
Maxtor Corporation
Nguyen Hiep T.
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