Browse Prior Art Database

Method of searching position for tape drive

IP.com Disclosure Number: IPCOM000013274D
Original Publication Date: 2000-Dec-01
Included in the Prior Art Database: 2003-Jun-18
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Abstract

Disclosed is a method for searching position of data on a tape medium of a linear tape drive. When a drive can not read data sequentially, drive scans the medium for a certain region and gets header information to make header vs position table, and then finds out the position of the target data from the table. By using this method, a drive can know the position of data without reading the bulk of the data.

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Method of searching position for tape drive

       Disclosed is a method for searching position of data on a
tape medium of a linear tape drive. When a drive can not read data
sequentially, drive scans the medium for a certain region and gets
header information to make header vs position table, and then finds
out the position of the target data from the table. By using this
method, a drive can know the position of data without reading the
bulk of the data.

   In the format of the object for this invention, user data can be
recorded any position on the medium. Normally, a drive can read
data sequentially but it cannot read proper data from the medium
due to medium defect, fragment due to over-writing and servo error.
Under such condition, a drive starts to skim the medium and gets
header information of each data.

   A unit of data and another unit are separated by tone pattern
called DSS (Data Set Separator). When DSS is detected by channel
circuit, the circuit stores header information of the data read
just before detection of DSS and at the same time the circuit also
gets position information from servo circuit. The channel circuit
store this information into a register and issues an interrupt
signal to CPU when it gets information of header and position.
Micro code read the register when it receives the interrupt signal
and store the information to a table on memory.

   Thus, Micro code can search the target unit of data from the
table made by this way. Figure below shows system schematic.

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