US 5,634,028 AGranted

Compact track address translation mapping system and method

AssigneeInternational Business Machines Corporation

InventorsJames T. Brady, Robert W. Shomler, May N. Wone

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Abstract

A computer-implemented method for translating from one DASD address to another DASD address initially stores a plurality of translation tables, one translation table for each first DASD coupled to a first processor. Each translation table includes at least a first data value for each cylinder in a first DASD which indicates whether or not the cylinder contains a start-of-extent address. If yes, the translation table has a corresponding translation entry which includes a first portion and a second portion. The first portion includes at least the start-of-extent address in the cylinder and a length of the extent of addresses associated with the start-of-extent address. The second portion includes a start-of-extent address for an address span in a second DASD that corresponds to the first portion. The method further determines, in response to receipt of an address in the first DASD (and from an associated DASD translation table), whether a cylinder identifier in the received address is associated with a first data value in the translation table that indicates a presence of a start-of-extent value. If yes, the method finds a corresponding translation entry and from a second portion thereof, determines an address in the second DASD that corresponds to the received first DASD address.

Claims10

Dependent claims

Computer apparatus for translating from one direct access storage device (DASD) address to another DASD address, each DASD address comprising a DASD device identifier (ID), a cylinder ID and a track ID, data being stored on e DASD from a start track and extending for an extent of addresses, comprising:

first processing means including at least one first DASD;
second processing means including at least one second DASD;
means for enabling data communications between said first and second processing means;
memory associated with said first processing means for storing at least one translation table, one translation table for each first DASD coupled to said first processing means, each translation table including at least a first data value for each cylinder in said first DASD which indicates whether a corresponding cylinder contains a start of extent address, and if yes, at least one corresponding translation entry comprising a first portion and a second portion, said first portion including at least said start of extent address and a length of the extent of addresses associated with said start of extent address, said second portion including a start of extent address for an address span in said second DASD that corresponds to said first portion;
and
logic means in said first processing means and responsive to receipt of a first DASD address to determine from a translation table in said memory that corresponds to said first DASD whether a cylinder ID in said first DASD address is associated with a first data value indicating a presence of a start of extent value and if yes, finding a corresponding translation entry and from a second portion thereof, determining an address in said second DASD that corresponds to said first DASD address.

3 more elements

A computer-implemented method for translating from one direct access storage device (DASD) address to another DASD address, each DASD address comprising a DASD device identifier (ID), a cylinder ID and a track ID, data being stored on a DASD from a start track and extending for an extent of addresses, said method comprising the steps of:

(a) storing at least one translation table, one translation table for each first DASD coupled to a first processing means, each translation table including at least a first data value for each cylinder in said first DASD which indicates whether a corresponding cylinder contains a start of extent address, and if yes, at least one corresponding translation entry which includes a first portion and a second portion, said first portion including at least said start of extent address and a length of the extent of addresses associated with said start of extent address, a second portion including a start of extent address for an address span in said second DASD that corresponds to said first portion;
(b) determining, in response to receipt of an address in said first DASD from a translation table in said memory that corresponds to said first DASD, whether a cylinder ID in said address is associated with a first data value indicating a presence of a start of extent value;
and if yes,
(c) finding a corresponding translation entry and from a second portion thereof, determining an address in said second DASD that corresponds to said address in said first DASD.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 08/356,696Filed 15 Dec 1994
Granted: 27 May 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G11C 29/74
Masking faults in memories by using spares or by reconfiguring: using duplex memories, i.e. using dual copies
G06F 3/0601
Digital input from, or digital output to, record carriers , e.g. RAID, emulated record carriers or networked record carriers: interfaces specially…
G06F 3/0608
Specifically adapted to achieve a particular effect: saving storage space on storage systems
G06F 3/0638
Making use of a particular technique: organizing or formatting or addressing of data