Browse Prior Art Database

Merge Overlap Writes in Disk Controller

IP.com Disclosure Number: IPCOM000103075D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 31K

Publishing Venue

IBM

Related People

Tsao, GY: AUTHOR

Abstract

A method is disclosed that reduces the number of disk write operations in a disk controller, which has the command queueing capability.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Merge Overlap Writes in Disk Controller

      A method is disclosed that reduces the number of disk write
operations in a disk controller, which has the command queueing
capability.

      If several write commands against one disk are queued in the
disk controller and are to be written to the same disk block (overlap
writes), the controller executes only the most recent overlap
command.  Once the write is successfully written to the disk, the
controller returns good status to each overlap write command in the
order they were received.  If the write is not successful, then the
controller returns failure status to each overlap command in the
order they were received.

      This method will be useful if operating software cannot
guarantee that all overlap writes are merged together before sending
the request to the disk controller.

      One possible application to use this method is log record
writes for database updates.  The overlap writes occur when several
log records can be packed into a single disk block and operating
software cannot afford to delay the write operations.

      Disclosed anonymously.