US 5,333,305 A · Method for improving partial stripe write performance in disk array subsystems

Abstract

A method and apparatus for improving disk performance during partial stripe write operations in a computer system having a disk array subsystem utilizing parity fault tolerance technique. When a partial stripe write generation is begun, the method determines if the area or stripe where the write is to occur is unused space in the file system. If not, the partial stripe write operation is performed using a preceding read operation to read the current data and parity information from the disk as would normally be done. However, if the write area is unused space in the file system, then the contents of the data stripe do not need to be preserved. In this instance, the partial stripe write operation can be performed without any preceding read operations. By obviating the necessity of a preceding read operation, much of the performance penalty of doing a partial stripe write in the case where the rest of the data stripe does not need to be preserved is removed.

Claims13

Dependent claims

A method for performing disk array write operations in a computer system disk array having a plurality of disk units each having a plurality of stripes for storing data and parity information, wherein the disk array utilizes parity fault tolerance techniques, the method comprising:

generating a data write operation to write valid data to a data stripe portion in the disk array;
determining if said write operation is a partial stripe write operation, wherein said partial stripe write operation includes writing said valid data to only a first portion of said data stripe portion;
determining if a second portion of said data stripe portion other than said first portion comprises unused space if said write operation is a partial stripe write operation;
generating parity information for said data stripe portion using only said valid data if said second portion comprises unused space;
and
writing said valid data to said first portion and said parity information to said parity information portion of said stripe after generating said parity information.

3 more elements

A computer system which performs disk array write operations, comprising:

a system bus;
a disk array coupled to said system bus having a plurality of disk units each having a plurality of stripes for storing data and parity information;
means coupled to said system bus for generating a data write operation to write valid data to a data stripe portion in said disk array;
means coupled to said write generating means for determining if said write operation is a partial stripe write operation, wherein said partial stripe write operation includes writing said valid data only to a only first portion of said data stripe portion;
means coupled to said partial stripe write determining means and said disk array for determining if a second portion of said data stripe portion comprises unused space if said write operation is a partial stripe write operation;
means coupled to said unused space determining means and said system bus receiving said data for generating parity information for said data stripe portion using only said valid data if said second portion comprises unused space;
and
means coupled to said parity information generating means, said system bus, and said disk array for writing said valid data to said first portion and said parity information to said parity information portion of said stripe.

5 more elements

Dependencies are inferred from the claim text.

Method for improving partial stripe write performance in disk array subsystems

Life of this patent

Method for improving partial stripe write performance in disk array subsystems

Life of this patent

Abstract

Claims13