Method and apparatus for optimizing record quality with varying track and linear density by allowing overlapping data tracks

A method and apparatus for optimizing data record quality on a disk for a pair of read and write heads, in which the write head is bigger, by adaptively varying linear and track density of overlapping recorded tracks to achieve a target storage capacity. In the method, target storage capacity and radial writing direction are selected. Read and write widths of heads are determined. A linear density and offset distance pairing for optimizing record quality at target storage capacity is determined, wherein offset distance is less than write width but greater than read width. The write head writes a track at the linear density, is offset in the radial direction by the offset distance, and the offset distance is stored. The write head writes a new track at the linear density. Offsetting, storing offset, and writing a new track are repeated until desired data is written into a cluster.

TECHNICAL FIELD

The present invention relates to the field of hard disk drive development, and more particularly to a method and apparatus for optimizing record quality with varying track and linear density by allowing overlapping data tracks.

BACKGROUND ART

Hard disk drives are used in almost all computer system operations. In fact, most computing systems are not operational without some type of hard disk drive to store the most basic computing information such as the boot operation, the operating system, the applications, and the like. In general, the hard disk drive is a device which may or may not be removable, but without which the computing system will generally not operate.

The basic hard disk drive model includes a storage disk or hard disk that spins at a designed rotational speed. An actuator arm with a suspended slider is utilized to reach out over the disk. The arm carries a head assembly that has a magnetic read/write transducer or head for reading/writing information to or from a location on the disk. The complete head assembly, e.g., the suspension and head, is called a head gimbal assembly (HGA).

In operation, the hard disk is rotated at a set speed via a spindle motor assembly having a central drive hub. There are tracks at known intervals across the disk. When a request for a read of a specific portion or track is received, the hard disk aligns the head, via the arm, over the specific track location and the head reads the information from the disk. In the same manner, when a request for a write of a specific portion or track is received, the hard disk aligns the head, via the arm, over the specific track location and the head writes the information to the disk.

Over the years, the disk and the head have undergone great reductions in their size. Much of the refinement has been driven by consumer demand for smaller and more portable hard drives such as those used in personal digital assistants (PDAs), Moving Picture Experts Group audio layer 3 (MP3) players, and the like. For example, the original hard disk drive had a disk diameter of 24 inches. Modern hard disk drives are much smaller and include disk diameters of less than 2.5 inches (micro drives are significantly smaller than that). Advances in magnetic recording density are also primary reasons for the reduction in size.

However, the increase of recording density requires decreased read and write track width and tight track width tolerance. It is becoming difficult to manufacture read and write heads to the tolerances required by today's small track sizes. When the write track width exceeds track pitch, erasure of adjacent tracks occurs. When the write track width is smaller than read width, the read head can easily pick track edge noise and interference data, data error rate degrades.

One solution to the problem is to use wider write heads, vary track and linear density, and write wide tracks that overlap each other, instead of tracks that are independent of each other. The track width is dependent on the offset between adjacent tracks at writing, not the write head track width. This gives the advantage of much relaxed tolerance requirement for the write head.

SUMMARY

A method and apparatus for optimizing data record quality on a disk for a pair of read and write heads, in which the write head is bigger, by adaptively varying linear and track density of overlapping recorded tracks to achieve a target storage capacity. In the method, target storage capacity and radial writing direction are selected. Read and write widths of heads are determined. A linear density and offset distance pairing for optimizing record quality at target storage capacity is determined, wherein offset distance is less than write width but greater than read width. The write head writes a track at the linear density, is offset in the radial direction by the offset distance, and the offset distance is stored. The write head writes a new track at the linear density. Offsetting, storing offset, and writing a new track are repeated until desired data is written into a cluster.

BEST MODES FOR CARRYING OUT THE INVENTION

Reference will now be made in detail to the alternative embodiment(s) of the present invention, a method and apparatus for optimizing record quality with varying track and linear density by allowing overlapping data tracks. While the invention will be described in conjunction with the alternative embodiment(s), it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims.

The discussion will begin with an overview of the operation a hard disk drive and components connected therewith, then proceed into a discussion of the operation of write heads and read heads in conjunction with the hard disk drive. For purposes of clarity, portions of the overview embodiment will describe the operation of the read head and the operation of the write head separately. It should be understood that even though the read and write heads are being described as separate components, in practice they are often fabricated as single device that performs the two separate functions of reading and writing data. The discussion will then focus on embodiments of a method for optimizing record quality by varying track and linear density to achieve a target storage capacity.

With reference now toFIG. 1, a schematic drawing of one embodiment of an information storage system comprising a magnetic hard disk file or drive111for a computer system is shown. Drive111has an outer housing or base113containing a disk pack having at least one media or magnetic disk115. A spindle motor assembly having a central drive hub117rotates the disk or disks115. An actuator121comprises a plurality of parallel actuator arms125(one shown) in the form of a comb that is movably or pivotally mounted to base113about a pivot assembly123. A controller119is also mounted to base113for selectively moving the comb of arms125relative to disk115.

In the embodiment shown, each arm125has extending from it at least one cantilevered electrical lead suspension (ELS)129. The ELS may be any form of lead suspension that can be used in a Data Access Storage Device, such as a HDD. A magnetic read/write transducer or head is mounted on a slider and secured to a flexure that is flexibly mounted to each suspension129. The read/write heads magnetically read data from and/or magnetically write data to disk115. The level of integration called the head gimbal assembly is the head and the slider230(seeFIG. 2), which are mounted on suspension127. The slider230(seeFIG. 2) is usually bonded to the end of ELS129.

ELS129has a spring-like quality, which biases or presses the air-bearing surface of the slider230(seeFIG. 2) against the disk115to cause the slider230(seeFIG. 2) to fly at a precise distance from the disk115. ELS129has a hinge area that provides for the spring-like quality, and a flexing interconnect that supports read and write traces through the hinge area. A voice coil133, free to move within a conventional voice coil motor magnet assembly134(top pole not shown), is also mounted to arms125opposite the head gimbal assemblies. Movement of the actuator121(indicated by arrow135) by controller119causes the head gimbal assemblies to move along radial arcs across tracks on the disk115until the heads settle on their set target tracks. The head gimbal assemblies operate in a conventional manner and always move in unison with one another, unless drive111uses multiple independent actuators (not shown) wherein the arms can move independently of one another.

Referring now toFIG. 2, a side view of an exemplary actuator200with a read/write head220from a hard disk drive111(shown inFIG. 1), in accordance with one embodiment of the present invention is shown. The actuator arm125has extending from it at least one suspension127with at least one ELS129(shown inFIG. 1). A magnetic read/write transducer or head220is mounted on a slider230and secured via a gimbal210that is coupled to each ELS129(shown inFIG. 1). The actuator arm125, is attached to a pivot assembly123.

Referring now toFIG. 3, a top plan view of an exemplary magnetic disk115showing the radial writing direction(s), in accordance with one embodiment of this invention is shown. The disk115has an outer diameter303and an inner diameter305. The head220, ofFIG. 2, is moved across the disk115to write and read data. The radial direction from the outer diameter303to the inner diameter305is shown by arrow307. The radial direction from the inner diameter305to the outer diameter303is shown by arrow309. In the embodiments of the present invention in which overlapping data tracks are written, the data can be written in a radial direction307from the outer diameter303to inner diameter305. The data can also be written in a radial direction309from the inner diameter305to the outer diameter303.

Referring now toFIG. 4, a magnified example of a read head407and write head409along with a cluster of overlapping data tracks400in accordance with one embodiment of the present invention is shown. An exemplary write head409is shown in relation to a track that it has written403. In the example the write head409is shown at the same width as the data track, this does not preclude a write head409, in accordance with embodiments of the present invention, from being bigger or smaller than the written data track that it writes. Due to the small nature of write heads409and the difficulties of manufacture, actual performance of write heads can vary widely from designed tolerances. Embodiments of the present invention are meant to work with write heads that have a wide variety of write widths411.

FIG. 4also shows a read head407relative to the non-overwritten portion421of the first data track401. Though the read head407is shown as slightly smaller than the non-overwritten portion421of the first data track401, this should not be viewed as a requirement for any embodiment of this invention. The embodiments of this invention are operable with a variety of read head407sizes so long as the effective read width417, which can be bigger or smaller than the width of the read head407, is narrower than the non-overwritten portion of the data track it is reading.

FIG. 4shows an example of how data can be written in overlapping tracks400in accordance with some embodiments of this invention. In this magnified Figure and the Figures that follow, the data tracks are shown as short straight lines. It should be understood that the actual data tracks are much smaller and when viewed with less magnification would in be long circular lines that go around the surface of the disk115, shown inFIG. 1, in concentric circles.

InFIG. 4, a first data track401is written. The write head409is then offset in a selected direction415by an offset distance405. The offset distance405will determine not only how far the write head409is moved, but also how much of the track is not overwritten421. In the embodiments of this invention containing overwritten data tracks, the offset distance405is equal in width to the non-overwritten area421of the data track. This non-overwritten area421is the portion of the data track that is readable by the read head407.

InFIG. 4, after the write head409is offset, a second data track402is written which partially overlaps and therefore partially overwrites the first data track401. The sections shown by dotted lines on the second track402represent overwritten area413of the first track401. The width of the overlap413can be calculated as [write width−offset distance]. The write head409is then offset again in the selected direction415and a third data track403is written that overlaps the second data track402by a small distance414equal to [write width−offset distance]. This process is repeated until all desired data is written into a cluster of these overlapping tracks400. InFIG. 4, the Nth track404represents the last track of data written into this exemplary cluster400of overlapping tracks.

FIG. 5is a magnified example of side-by-side clusters500of overlapping data tracks in accordance with one embodiment of the present invention. In the first exemplary cluster501there is a first written track401, a second written track402that partially overwrites the first track401, and a third written track403that partially overwrites the second track402. There is then a second exemplary cluster510of overlapping data tracks containing a first written track511, a second written track512that partially overwrites the first track511, and a third written track513that partially overwrites the second written track512. This second cluster510is written in the same overlapping manner as the first cluster501. These tracks are written in the same manner as the overlapping data tracks inFIG. 4. The tracks in clusters501and510are written with a write head409that has a write width411as shown. The arrow515shows the direction of writing for the overlapping tracks.

The first cluster501and second cluster510are separated by a space, or guard band507, that is slightly greater in width than the write width411of the write head409. The purpose of the guard band507is to prevent the data in the last track403of the first cluster501from being overwritten by the first track511of the second cluster510. In the example only three tracks have been shown in each exemplary cluster. It should be understood that clusters can contain fewer tracks, but will likely contain more tracks. For efficient use of surface area on a disk, such as disk115inFIG. 1, overlapping clusters of one hundred tracks or more are preferred. Further,FIG. 5is not intended to indicate that this embodiment is limited to two clusters of data tracks. It should be understood that this embodiment can contain a plurality of clusters, each separated from the next cluster by a guard band as show.

Referring now toFIG. 6, a magnified example of side-by-side clusters600of overlapping and non-overlapping data tracks in accordance with one embodiment of the present invention is shown. The tracks in clusters605and610are written with a write head409that has a write width411as shown. The arrow615shows the direction of writing for the cluster of overlapping data tracks605. The direction of writing615could also be used with the non-overlapping cluster of data tracks610, but that is not required for embodiments of this invention.

Referring toFIG. 6, in the first exemplary cluster of overlapping data tracks605there is a first written track601, a second written track602that partially overwrites the first track601, and a third written track603that partially overwrites the second track602. The tracks in this cluster605are written in the same manner as the overlapping data tracks400inFIG. 4, even though they are shown as being more tightly spaced. There is then a second exemplary cluster of non-overlapping data tracks610containing a first written track611, a second written track612separated by a space607from the first data track611, and a third written track613separated from the second written track612by a space608equivalent to the first space607. The second cluster610is separated from the first cluster605by a guard band507. This second cluster610is written in a more traditional manner with non-overlapping data tracks, which allows the tracks to be written in a non-sequential manner. The labels of first, second, and third track are used for convenience here, and are not meant to indicate that the tracks in the non-overlapping data cluster need to be written in any particular order.

InFIG. 6, the first cluster605and second cluster610are separated by a space, or guard band507, that is slightly wider in width than the write width411of the write head409. The purpose of the guard band507is to prevent the data in the last track603of the first cluster605from being overwritten by the first track611of the second cluster610. In the example only three tracks have been shown in each exemplary cluster. It should be understood that clusters can contain fewer tracks, but will likely contain more tracks. Further,FIG. 6is not intended to indicate that this embodiment is limited to two clusters of data tracks. It should be understood that this embodiment can contain a plurality of clusters of overlapping tracks and a plurality of clusters of non-overlapping tracks, each cluster separated from the next cluster by a guard band507as show.

FIG. 6, demonstrates the advantage of writing some, or all clusters of data with overlapping tracks. Spaces between tracks can be reduced or eliminated. This gives the ability to compensate for out of tolerance heads by manipulating the linear density and track density to prevent sacrificing the targeted storage capacity (or areal density).

Referring now toFIG. 7, a magnified example of a cluster700of overlapping data tracks written with a low track density and a high linear density in accordance with one embodiment of the present invention is shown. A first data track701is written. The linear density of this first data track701is high, as represented by the many bits705of data with only small spaces707between them. The write head409is shifted in a selected direction715by a wide offset709. A second data track702is written that slightly overlaps717the first track701. This second track702is also written at a high linear density. The write head409is shifted again in the selected direction715by a wide offset710. A third data track703is written that overlaps the second data track702by an overlap distance718equal to the previous overlap717. The third track703is also written at a high linear density. This process is repeated until all desired data is written into the cluster. The last data track of this cluster is represented by the Nth track711.

FIG. 7shows how tracks can be overlapped a slight distance717and written at a high linear density. In one embodiment, this combination of high linear density and lower track density is selected to achieve a target storage capacity (or areal density) in many situations. The example shown inFIG. 7can be useful in a situation where the read head407, write head409, or both are manufactured slightly out of design tolerance. As a specific example, it is useful in a situation where the write head409is not capable of writing narrower tracks, and a target storage capacity (or areal density) cannot be met by writing only non-overlapping tracks with spaces between the tracks. Some, or all clusters on a disk, such as disk115inFIG. 1, can be written as shown inFIG. 7to enable meeting the designed storage capacity (or areal density), even with a head (or heads) slightly out of design tolerance.

Referring now toFIG. 8, a magnified example of a cluster800of overlapping data tracks written with a medium track density and a medium linear density in accordance with one embodiment of the present invention is shown. A first data track801is written. The linear density of this first track801is medium as compared to that ofFIG. 7andFIG. 9, and as represented by the bits805of data with wider spaces807between them than the spaces inFIG. 7. The write head409is shifted in a selected direction815by a medium offset distance809, as compared toFIG. 7andFIG. 9. A second data track802is written that overlaps817the first track801. This second track802is also written at a medium linear density. The write head409is shifted again in the selected direction815by a medium offset distance810. A third data track803is written that overlaps the second track802by an overlap818equal to the previous overlap distance817. The third track803is also written at a medium linear density. This process is repeated until all desired data is written into the cluster800. The last data track of this cluster800is represented by the Nth track811.

FIG. 8shows how tracks can be overlapped a medium distance817, and written at a medium linear density. In one embodiment, this combination of medium linear density and medium track density is selected to achieve a target storage capacity (or areal density) in many situations. The example shown inFIG. 8can be useful in a situation where the read head407, write head409, or both are manufactured slightly out of design tolerance. As a specific example, it is useful in a situation where the write width411of the write head409is within design specification, but it cannot write up to the designed linear density. This could prevent the drive from meeting its target storage capacity (or areal density) if only non-overlapping tracks with spaces between the tracks were written. Some, or all clusters on a disk, such as disk115inFIG. 1, can be written as shown inFIG. 8to enable the linear density to be relaxed to a level the write head can operate at. The space saved by writing some or all of the clusters with overlapping tracks allows for meeting the designed storage capacity (or areal density), even with a head (or heads) slightly out of design tolerance.

Referring now toFIG. 9, a magnified example of a cluster900of overlapping data tracks written with a high track density and a low linear density in accordance with one embodiment of the present invention is shown. A first data track901is written. The linear density of this first track901is low as compared to that ofFIG. 7andFIG. 8, and as represented by the bits905of data with very wide spaces907between them. The write head409is shifted in a selected direction915by a narrow offset distance909, as compared toFIG. 7andFIG. 9. A second data track902is written that greatly overlaps917the first track901. This second track902is also written at a low linear density. The write head409is shifted again in the selected direction915by a narrow distance910. A third data track903is written that overlaps the second track902by an overlap distance918equal to the previous overlap distance917. The third track903is also written at a low linear density. This process is repeated until all desired data is written into the cluster900. The last data track of this cluster900is represented by the Nth track911.

FIG. 9shows how tracks can be overlapped a wide distance917, and written at a low linear density. In one embodiment, this combination of low linear density and high track density is selected to achieve a target storage capacity (or areal density) in many situations. The example shown inFIG. 9can be useful in a situation where the read head407, write head409, or both are manufactured out of design tolerance. As a specific example, it is useful in a situation where the write width411of the write head409is significantly wider than the design specification. This could prevent the drive from meeting its target storage capacity (or areal density) if only non-overlapping tracks with spaces between the tracks were written. Some, or all clusters on a disk, such as disk115inFIG. 1, can be written as shown inFIG. 9to enable meeting the designed storage capacity (or areal density), even with a head (or heads) out of design tolerance.

While the examples provided inFIG. 7,FIG. 8, andFIG. 9are specific, the present invention is suitable to alternative embodiments. For example, the method of the present invention is applicable to embodiments ranging from recording at low track density and low linear density, to embodiments recording at high track density and high linear density. Likewise, for simplicity of example, track density and linear density were shown at only three gradients of low, medium, and high. Embodiments of the present invention are suitable to other gradients as required by the particulars of a set of read and write heads and as required by the target storage capacity.

The embodiments of this invention are useful in many situations. In one embodiment, a disk drive maker can manufacture identical disks with an initial target disk capacity of 10 Gigabytes of data. The manufacturer can then utilize the methods described to format these disks in various capacities of, for example, 1, 5, 7, 10, and 15 Gigabytes, in response to consumer demand for different storage capacities. Instead of just having traditional non-overlapping tracks, drives can be produced with a plurality of different formats containing exclusively overlapping tracks, or a combination of overlapping tracks and non-overlapping tracks. Drives with exclusively or mostly overlapping tracks can be customized to store movies or video segments of various lengths without going to the expense of designing and manufacturing the drives specifically for the size and function needed by a particular application. A flexible and varied product line is offered without additional design and manufacturing expenses, and inventory and production are streamlined because of uniform disk size.

In another embodiment, the storage capacity of a disk can be partially decoupled from the read and write heads designed for use with it. Fluctuations in the tolerances of read and write heads occur in production runs. It is common to find that many write heads in a production run will write a track width that is 50% wider or narrower than the design specification for the disks and drives they are designed to be used with. It is also common to find similar fluctuations in the actual read widths of read heads within production runs. Normally these read and write heads that are out of tolerance are disposed of as useless. However, utilizing the methods described, many out of tolerance heads can be used instead of being disposed of.

For instance, by writing overlapping data tracks, write width is decoupled from track width. Track width is determined instead by how far the write head is offset before the next track is written (partially on top of the previous track). This means narrow data tracks can be produced with write heads that write wide tracks. When narrower tracks are written than the disk and head design specifications call for, either with a narrower writing head or with narrow tracks created by overlapping, linear density can be relaxed and a target storage capacity can still be met. Conversely, if narrower tracks are written than the design specification calls for, and linear density is not relaxed, or is instead increased, the result is increased storage capacity in the area of the disk where the overlapping tracks are written. The capability to utilize write heads that would have previously been discarded for being out of tolerance translates into cost savings through increased manufacturing efficiency.

Writing overlapping tracks also allows for taking advantage of a read head that is capable of reading a narrower track that it was designed to read. Written track width can be tailored to the capability of the read head. This will allow the target storage capacity to be realized with a relaxed linear density. Further, if the linear density is instead maintained or increased, a greater target storage capacity can be achieved. If the read head is out of tolerance such that it can only read tracks wider than the design specification, then linear density can be increased to achieve the target storage capacity while utilizing the out of tolerance read head. The capability to use read heads that read both wider and narrower tracks than called for in the manufacturing specification means that many read heads can be used that would previously have been discarded as being out of tolerance. This translates into cost savings through improved manufacturing efficiency.

In another embodiment, the drive tests the actual performance of the read and write heads, then using the methods described, stores data on the drive in a manner that optimizes storage capacity for the particular combination of heads and disks being used. Drives formatted in this manner would likely be very useful for data backup, or for storage of video, music, or other long and mostly sequentially writable data steams.

Referring now toFIG. 10, a flowchart1000of a method for optimizing record quality by varying track and linear density to achieve a target storage capacity in accordance with one embodiment of the present invention is shown.

With reference now to block1002ofFIG. 10and toFIG. 1, one embodiment provides selecting a target storage capacity. In this block, a target storage capacity for some portion or for the entirety of disk115is selected.

With reference now to block1004ofFIG. 10and toFIG. 3, one embodiment provides selecting a radial direction (307or309) to write data tracks. Overlapping data tracks are written in sequential order, either in a radial direction307from the outer diameter303toward the inner diameter305of the disk115or in a radial direction309from the inner diameter305toward the outer diameter303of the disk115.

With reference now to block1006ofFIG. 10and toFIG. 4, one embodiment provides for determining a write width411for the write head409. The write head409is tested to determine the width of track411that it writes.

With reference now to block1008ofFIG. 10and toFIG. 4, one embodiment provides for determining a read width417for the read head407. The read head407is tested to determine the smallest width of a data track it can read.

With reference now to block1010ofFIG. 10and toFIG. 4, one embodiment provides for determining a pairing of a linear density and an offset distance to optimize data record quality for the combination of said write head409, said read head407, and said target storage capacity. Given a known write width411, read width417, and target storage capacity (or areal density), the linear density (spacing of bits on a track) and offset405(which determines effective width of written tracks) can be selected utilizing the equation [area density=(linear density)(track density)] to allow the combination of read and write heads to meet the target storage capacity. There are some limitations. For instance, the linear density cannot exceed the capabilities of the read or write head. The read width417must always be smaller than the un-overwritten portion421of the data tracks. Additionally, the offset distance405must be smaller than the write width411, if it is desired to have overlapping data tracks.

With reference now to block1012ofFIG. 10and toFIG. 4, one embodiment provides for writing a first data track401on a disk (such as disk115inFIG. 1) at said linear density with said write head409. In a cluster of overlapping tracks400, this will be the first track401in a series of sequentially written data tracks.

With reference now to block1014ofFIG. 10and toFIG. 4, one embodiment provides for offsetting said write head in said selected radial direction415by said selected offset distance405. This positions the write head properly to write the next track. It also determines how much of the track is left as readable, or un-overwritten421. Because there is no spacing between the tracks, track pitch is equal to the offset distance405.

With reference now to block1016ofFIG. 10and toFIG. 4, one embodiment provides for storing said offset distance405. This facilitates location of the track(s) for future read back, as the read head407will be positioned over a track and/or offset from track to track to read data that is written.

With reference now to block1018ofFIG. 10and toFIG. 4, one embodiment provides for writing a new data track onto said disk (such as disk115inFIG. 1) with said write head409at said linear density. This provides for writing a second data track402that overlaps the first data track401by a distance413equal to [write width−offset distance].

With reference now to block1020ofFIG. 10andFIG. 4, one embodiment provides for repeating said offsetting of said write head409, said storing said offset distance405, and said writing a new data track onto said disk (such as disk115inFIG. 1) with said write head409at said linear density until all desired data has been written into a cluster400. This block provides for writing a third data track403and any additional data tracks in a sequential manner, until all data is written into a cluster400of overlapping data tracks.

Referring now toFIG. 1, a flowchart1100of a method for optimizing record quality by varying track and linear density to achieve a target storage capacity with clusters of overlapping data tracks in accordance with one embodiment of the present invention is shown.

With reference now to blocks1002through1020ofFIG. 11, these blocks are the same as previously described inFIG. 10.

With reference now to block1102ofFIG. 11and toFIG. 5, one embodiment provides for leaving a guard band507slightly greater than said write width411at the end of said cluster501. This is done to prevent overwriting the last track403of a cluster of data tracks501with the first track511of the next cluster of data tracks510.

With reference now to block1104ofFIG. 11and toFIG. 5, one embodiment provides for writing data to said disk (such as disk115inFIG. 1) in a plurality of said clusters500, each said cluster separated by said guard bands507. This can be useful if writing two or more clusters of sequentially written data. Music files and video files are some examples of such sequentially written data.

Referring now toFIG. 12, a flowchart1200of a method for optimizing record quality by varying track and linear density to achieve a target storage capacity with clusters of overlapping and non-overlapping data tracks in accordance with one embodiment of the present invention is shown.

With reference now to blocks1002through1020ofFIG. 12, these blocks are the same as previously described inFIG. 10.

With reference now to blocks1102and1104ofFIG. 12, these blocks are the same as previously described inFIG. 11.

With reference now to block1202ofFIG. 12and toFIG. 6, one embodiment provides for writing data to said disk (such as disk115inFIG. 1) in a plurality of other clusters610separated by guard bands507, wherein data tracks within said clusters do not overlap. This provides for writing some data using the more conventional manner of non-overlapping tracks. This is useful in cases where some of the data stored can be written sequentially into clusters605, and some cannot. The non-overwritten tracks610provide flexibility for writing and reading data non-sequentially.

Referring now toFIG. 13, a flowchart1300of a method for optimizing record quality by varying track and linear density to achieve a target storage capacity and then reading the recorded data in accordance with one embodiment of the present invention is shown.

With reference now to blocks1002through1020ofFIG. 13, these blocks are the same as previously described inFIG. 10.

With reference now to block1302ofFIG. 13and toFIG. 4, one embodiment provides for reading said data tracks in said cluster with said read head407. This is useful for retrieval of data that has been written. Stored information about the location of the written data tracks, with respect to one another, is used to position the read head407above the data tracks for reading the recorded data and/or to offset the read head407from track to track as needed.

While the methods of the embodiment illustrated in flow charts1000,1100,1200and1300show specific sequences and quantity of steps, the present invention is suitable to alternative embodiments. For example, not all the steps provided for in the methods are required for the present invention. Furthermore, additional steps can be added to the steps presented in the present embodiment. Likewise, the sequences of steps can be modified depending upon the application.

The alternative embodiments of the present invention, a method and apparatus for optimizing record quality with varying track and linear density by allowing overlapping data tracks are thus described. While the present invention has been described in particular embodiments, it should be appreciated that the present invention should not be construed as limited by such embodiments, but rather construed according to the below claims.