Browse Prior Art Database

Unoriented Multi-Track Pre-Stage

IP.com Disclosure Number: IPCOM000113972D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Candelaria, SK: AUTHOR [+4]

Abstract

A more efficient method for the 3990 Control Unit to copy multiple non-consecutive tracks from a device to its subsystem storage is disclosed. The disclosed method is referred to as Unoriented Multi-Track Stage.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 79% of the total text.

Unoriented Multi-Track Pre-Stage

      A more efficient method for the 3990 Control Unit to copy
multiple non-consecutive tracks from a device to its subsystem
storage is disclosed.  The disclosed method is referred to as
Unoriented Multi-Track Stage.

      The 3990 Control Unit exploits idle time, when it is not
currently servicing a channel I/O request, by copying tracks from its
attached disk devices to its subsystem storage.  This copy operation
is referred to as a pre-stage operation.

      Unoriented Multi-Track Stage eliminates latency caused when
orienting to a particular track location by initiating its pre-stage
with an unoriented seek/locate operation.  An unoriented seek/locate
is defined as the operation that moves the seek arm to the proper
cylinder on the device and orients to the first record encountered.
Unoriented Multi-Track Stage then begins copying records immediately
to the subsystem storage.  When it reaches index of the first track
being pre-staged it switches to the next track to be pre-staged.  The
next track to be pre-staged need not be the very next sequential
track following the track just pre-staged.  It is only required that
all tracks to be pre-staged reside on the same cylinder of the
subject device.  The next track is pre-staged beginning at its first
record and continuing until its index and head switching to the next
track to be pre-staged.  These head switches continue until all
tracks to be pre-staged are pre-stage...