Browse Prior Art Database

Reduce Low-End DASD Power by Adding Non-Volatile Memory Buffer

IP.com Disclosure Number: IPCOM000117508D
Original Publication Date: 1996-Mar-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Dang, HP: AUTHOR [+2]

Abstract

Small form-factor files, i.e., 2.5" and 1.8" files, for the Laptop and Notebook applications have to be energy efficient. One way of saving power is to turn off the device when it is not being used. For DASD, it means moving the heads to the park zone (or unloading the heads), spinning down the disk and turning off the majority of the electronics. When information is needed from the file, the disk is spun up to the operating speed (around 3600 rpm), the heads are moved to the desired location, data is read and is sent back to the host. It takes 2 to 5 seconds and 7 to 27 watt-sec to spin up the disk. This is one of the reasons why the file is not power down too often.

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This is the abbreviated version, containing approximately 58% of the total text.

Reduce Low-End DASD Power by Adding Non-Volatile Memory Buffer

      Small form-factor files, i.e., 2.5" and 1.8" files, for the
Laptop and Notebook applications have to be energy efficient.  One
way of saving power is to turn off the device when it is not being
used.  For DASD, it means moving the heads to the park zone (or
unloading the heads), spinning down the disk and turning off the
majority of the electronics.  When information is needed from the
file, the disk is spun up to the operating speed (around 3600 rpm),
the heads are moved to the desired location, data is read and is sent
back to the host.  It takes 2 to 5 seconds and 7 to 27 watt-sec to
spin up the disk.  This is one of the reasons why the file is not
power down too often.

      In many applications running on the portable computers, i.e.,
word processor, spreadsheet, business graphics..., most of the times
the user reads one file and makes modifications to that same file
(data file).

      For this type of disk accessing, one could expand the memory
hierarchy and add a small non-volatile memory buffer between the disk
and host.  This buffer could be battery-backed SRAM or Flash Ram.
The latter one is more suitable for this application in terms of
capacity, size, and power.

      A typical Flash RAM, such as the Intel 28F010 offers 128K
bytes, takes 171 mW-sec to program, 136 mW-sec to erase and consumes
no power to retain data.  It has 120 ns read-access and 10 us
byte-program.

 ...