Browse Prior Art Database

Data Storage

IP.com Disclosure Number: IPCOM000089667D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 42K

Publishing Venue

IBM

Related People

Aziz, RA: AUTHOR

Abstract

Record storage disk capacity is increased by using spiral tracks with uniform density of recording. Each segment of the disk having a spiral track is preferably recorded at one time while permitting multiple reads of all or any portion of the recorded spiral track. The guard band associated with disk record storage concentric track configurations can be eliminated. In a preferred form, recording of the spiral track includes recording a servo track in a buried fashion with the data track; that is, the servo track will contain a low frequency signal or band of signals and is recorded deep into the medium, whereas the data recording is at a higher frequency and is recorded at the surface of the record medium. Offset independent gaps permit simultaneous servo and data recording.

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Data Storage

Record storage disk capacity is increased by using spiral tracks with uniform density of recording. Each segment of the disk having a spiral track is preferably recorded at one time while permitting multiple reads of all or any portion of the recorded spiral track. The guard band associated with disk record storage concentric track configurations can be eliminated. In a preferred form, recording of the spiral track includes recording a servo track in a buried fashion with the data track; that is, the servo track will contain a low frequency signal or band of signals and is recorded deep into the medium, whereas the data recording is at a higher frequency and is recorded at the surface of the record medium. Offset independent gaps permit simultaneous servo and data recording.

Using the above-described techniques, data capacity of each disk surface is increased by about two. A fifty percent increase in a single band disk is achieved by using constant density, as opposed to constant frequency, recording. Additionally, because of the elimination of guard bands, the track density, i.e., tracks per millimeter, can be increased by at least fifty percent. It is preferred that, in writing, the radial accessors be slewed synchronously with the rotation of the disk in a feed forward or open loop manner such that perturbations of disk rotation can be ignored. Previous servo and data recording on each disk surface/ band was erased prior to re-recording. Overwriting can be used; however, erasure is preferred.

Because head-to-medium spacing may vary with radius, during the write mode write current amplitude may be adjusted to accommodate such spacing perturbations. During readback, equalization characteristics are adjusted to accommodate the increase in frequency with the increase in radius. A banded spiral disk, as shown in the lower right hand corner of the drawing, reduces the frequency change encountered over a disk surface while maintaining high capacity.

An application of such disk storage is in a data base store level wherein disks having a single spiral track may be interleaved with disks having banded spiral tracks. Application of the storage system to diverse uses will dictate the intermix of the disk formats.

Each of the disk devices includes a radial accessor with a "pause" mode. The pause mode is designed to reduce the buffer memory requirements in transferring data signals, either the NCI (noncoded information) type or the encoded data type, between the disk and utilization devices or an upper store level involving page memory. In general, a single rotation of the disk is read and stored in buffer memory.

At this time the radial accessor is held to its radial position, i.e., does not slew, as the buffer memory has received the signals through the recording channel and supplies them to the uniform density, the uniform frequency converter, and the data decompaction. The elapsed time cannot be more than

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