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Write Narrow/Read Wide Home Address Sectors in Magnetic Recording Disk File

IP.com Disclosure Number: IPCOM000060980D
Original Publication Date: 1986-Jun-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 94K

Publishing Venue

IBM

Related People

Albrecht, DW: AUTHOR

Abstract

At the completion of the assembly process for a magnetic recording disk file, the home address sector is written for each data track on each data disk. The resulting home address sector is as illustrated in Fig. 1. After the disk file has been in field use for some time, stress and temperature can cause slight movement and creep in the mechanical components. This can cause the centerlines of the data tracks to be shifted with respect to the home address sectors, as shown in Fig. 2. This long term "creep" does not necessarily cause an increase in the error rate on the data tracks. This is because data is constantly being rewritten. Therefore, the adjacent track overlap (i.e., adjacent track noise and/or old information) is not necessarily any greater than when the disk file was new; i.e.

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Write Narrow/Read Wide Home Address Sectors in Magnetic Recording Disk File

At the completion of the assembly process for a magnetic recording disk file, the home address sector is written for each data track on each data disk. The resulting home address sector is as illustrated in Fig. 1. After the disk file has been in field use for some time, stress and temperature can cause slight movement and creep in the mechanical components. This can cause the centerlines of the data tracks to be shifted with respect to the home address sectors, as shown in Fig. 2. This long term "creep" does not necessarily cause an increase in the error rate on the data tracks. This is because data is constantly being rewritten. Therefore, the adjacent track overlap (i.e., adjacent track noise and/or old information) is not necessarily any greater than when the disk file was new; i.e., the signal-to-noise ratio (S/N) for the data tracks has not changed as a result of the creep. However, as shown in Fig. 2 for track #2, the S/N for the head when it tries to read the home address can be far worse than when the file was new because the head can read significant adjacent track noise from the home address in track #3. This is because none of the home address sectors in the tracks have ever been rewritten. If the S/N is low enough, the home address can not be read. This problem in the home address sectors can be avoided if the home address is written narrow with AC- or DC- erased guard bands...