Browse Prior Art Database

Fast Zeroing of a Storage Device

IP.com Disclosure Number: IPCOM000112084D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 4 page(s) / 110K

Publishing Venue

IBM

Related People

Faunce, MS: AUTHOR [+5]

Abstract

Disclosed is a process for the fast zeroing (virtual formatting) of a Direct Access Storage Device (DASD), making the device look like it was formatted, whether it really was or not. The key is to "manufacture" data sectors containing all zeros and pass one of these manufactured sectors to the computing system in response to each read sector request, until a sector has been written with data. Any subsequent read request from the system for this sector would then be filled from an actual read of the sector. The process also provides for writing some data pattern other than zero ( a "Write Pattern Bytes" type of operation) and in addition, a fast "unformat" operation.

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

Fast Zeroing of a Storage Device

      Disclosed is a process for the fast zeroing (virtual
formatting) of a Direct Access Storage Device (DASD), making the
device look like it was formatted, whether it really was or not.  The
key is to "manufacture" data sectors containing all zeros and pass
one of these manufactured sectors to the computing system in response
to each read sector request, until a sector has been written with
data.  Any subsequent read request from the system for this sector
would then be filled from an actual read of the sector.  The process
also provides for writing some data pattern other than zero ( a
"Write Pattern Bytes" type of operation) and in addition, a fast
"unformat" operation.

      The Figure describes a Direct Access Storage Device (DASD) 1,
only one of the many possible embodiments of this invention, and
should not be construed as in any way portraying a limit on the
invention's claims.  Shown is the DASD's storage medium 2 and an
illustration of a few of the medium's many sectors in which
information can be stored.  There is also a Command Decoding,
Control, and Data Switching element 3 which handles the interface to
a computing system and controls all normal operations of the device.
The additional parts needed for implementing this invention are:

o   A non-volatile "means of keeping track" 4 of whether or not a
    storage medium sector has been written with data at least once.
    One possible embodiment could be via a commercially available
    "Flash Memory" which clears all bits to zero in response to a
    command, although a different implementation could allow
    individual bits to be set to zero for a "write pattern bytes" of
    one sector.

o   A "Data Factory" 5 which either "manufactures" a new data sector
    containing a previously supplied data pattern 6, or just passes
    data from the storage medium 7, sending its output via the
    Command Decoding, Control, and Data Switching element 3.

o   A "Decision Manager" 8 which examines bits inside the "means of
    keeping track" and controls the "Data Factory" to either
    manufacture a new data segment 9 or output data from the storage
    medium unchanged 10.

      There is a conceptual link 11 between sector 1 of the storage
medium 2 and bit 1 12 of the "means of keeping tr...