Browse Prior Art Database

Sector Write Completion During Emergency Power Off

IP.com Disclosure Number: IPCOM000118633D
Original Publication Date: 1997-Apr-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Rowan, BS: AUTHOR [+2]

Abstract

Disclosed is a method to complete a pending sector write operation in a Direct Access Storage Device (DASD) when the power supply is interrupted or turned off. This method provides a means to utilize energy stored in both the spfinish writing a sector after the power supply interruption or Emergency Power Off (EPO) event, reducing the number of sectors that would need to be rewritten as part of the recovery process to interrupting a write operation. By providing sufficient energy storage, it is possible to complete a write operation to multiple sectors without the need for recovery.

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Sector Write Completion During Emergency Power Off

      Disclosed is a method to complete a pending sector write
operation in a Direct Access Storage Device (DASD) when the power
supply is interrupted or turned off.  This method provides a means to
utilize energy stored in both the spfinish writing a sector after the
power supply interruption or Emergency Power Off (EPO) event,
reducing the number of sectors that would need to be rewritten as
part of the recovery process to interrupting a write operation.  By
providing sufficient energy storage, it is possible to complete a
write operation  to multiple sectors without the need for recovery.

      Most DASD suspend pending write operations at the time the EPO
is detected by the power supply monitoring electronics.  If the EPO
occurs while writing a sector, the write to that sector is not
completed.  The data being written must be rewritten as part of a
recovery process or it may be lost when an EPO occurs.

      To allow a pending sector write operation to be completed,
additional energy is made available by using energy stored in the
motor control circuit's bulk decoupling and energy storage capacitors
and the  energy stored in the rotating spindle motor.  Additional
energy could be  stored by adding components specifically to store
energy such as with a  battery or other means.  This additional
energy could be used to extend  the time available for writing after
an EPO event so more than one secto...