Browse Prior Art Database

Variable Block Formatting of Sector Servo DASD Devices

IP.com Disclosure Number: IPCOM000122260D
Original Publication Date: 1991-Nov-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Floryance, GG: AUTHOR

Abstract

Disclosed is a format method to provide efficient support for variable data block sizes on a sector servo DASD device by allowing portions of the data block to exist both before and after a servo burst.

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Variable Block Formatting of Sector Servo DASD Devices

      Disclosed is a format method to provide efficient support
for variable data block sizes on a sector servo DASD device by
allowing portions of the data block to exist both before and after a
servo burst.

      There are two separate techniques associated with variable
block formatting.  First is the splitting of a logical block of data
such that part of the data occurs before and the remaining data
occurs after the servo burst. This will be referred to as BLOCK
SPLIT.  The second technique is to disassociate the number and
location of ID fields from the servo bursts.  This will be referred
to as SERVO/DATA DISASSOCIATION and requires a clarification of
terms.  The term DATA SECTOR will be used to explicitly refer to a
data area containing an ID field and one or more data blocks.  A DATA
SECTOR may be bounded on one end, both ends or neither end by a servo
burst.  A DATA SECTOR may also encompass zero or more servo bursts.

      The BLOCK SPLIT technique is illustrated in the figure where a
portion of a track with five contiguous servo bursts is shown.  The
BLOCK SPLIT technique is shown with data block 7 (DB7) whose first
half occurs before and the second half occurs after servo burst 2
(SVO2).  BLOCK SPLIT is also shown for data blocks DB15, DB22, DB30
and DB37.

      The SERVO/DATA DISASSOCIATION technique is also shown in the
figure where ID 2 (ID2) occurs midway between servo bursts S...