Browse Prior Art Database

Half Latency Format for Hard Disk Drive

IP.com Disclosure Number: IPCOM000122508D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 95K

Publishing Venue

IBM

Related People

Lee, S: AUTHOR [+3]

Abstract

Disclosed is a disk format and data handling for shortening latency time by 50% for hard disk drives. The format is a data track that has twin sectors with the same address, and whose locations are symmetrical about the center point of the track. In write operation with this format, the sector which is first accessed between the twin sectors is written first, and then the other sector of the pair or twin is processed during drive idling by copying the data from the sector first written. In read operation, only the sector which is first accessed between the twin sectors is simply read.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Half Latency Format for Hard Disk Drive

      Disclosed is a disk format and data handling for
shortening latency time by 50% for hard disk drives. The format is a
data track that has twin sectors with the same address, and whose
locations are symmetrical about the center point of the track. In
write operation with this format, the sector which is first accessed
between the twin sectors is written first, and then the other sector
of the pair or twin is processed during drive idling by copying the
data from the sector first written. In read operation, only the
sector which is first accessed between the twin sectors is simply
read.

      The disk format and the data handling will be best understood
with reference to the example of the 4-sector formatting case
described on the next page.

      Data formatting on the disk is shown in Fig. 1.   Each track
has 4 pairs of actual (physical) sectors (twin sectors) which have
the same logical address. The sectors which compose each pair or twin
are located at the position symmetrical about center point of the
track.  In case of formatting, the logical sector number corresponds
to the actual sector number, as shown in Fig. 2.  The logical sector
number is used as the address for an interface with external data
control. On the other hand, the actual (physical) sector number is
used for the internal data handling of the drive. Each sector has a
flag for the purpose of copy operation, and a main memory of the
drive provides a table of the flags shown in Fig. 2.

      The data handling (write, read, copy, and flagging operation)
scheme is described as follows;
 - Flagging : a) When the write operation is completed, a flag of the
actual written sector is set.
               b) When the copy operation is completed, a flag is
cleared.
 - Write    : a) When the drive receives a write command, the flag
table is referred to [*].
        ...