US 2008/0301203 A1 · MANAGING A SNAPSHOT STORED WITHIN A FILE SYSTEM SPACE FOR EFFICIENT DETECTING OF IN-USE BLOCKS

Abstract

In one embodiment, at least one snapshot thread manages a point in time snapshot of a file system stored within the space allocated to the file system. The snapshot thread tracks, for at least one block of the plurality of blocks of the file system, a separate entry in a snapshot map specifying if each at least one block is newly allocated following the creation of the point in time snapshot and specifying an addressed location of a snapshot copy of the at least one block if copied. Separately, a file system handling thread tracks a mapping of an allocation state of each of said plurality of blocks of the file system. Responsive to detecting the file system triggered to write or delete a particular block from among the at least one block of the file system, the snapshot thread allows the file system to write to or delete the particular block without making a snapshot copy of the particular block if a particular entry for the particular block in the snapshot map specifies the particular block is newly allocated, wherein a block marked newly allocated was not in-use at the point in time of the file system snapshot.

Claims19

Dependent claims

A method for managing a point in time snapshot of a file system stored within the space allocated to the file system, comprising:

tracking, for at least one block of the plurality of blocks of the file system, a separate entry in a snapshot map specifying if each at least one block is newly allocated following the creation of the point in time snapshot and specifying an addressed location of a snapshot copy of the at least one block if copied, separately from tracking a mapping of an allocation state of each of said plurality of blocks of the file system;
and
responsive to detecting the file system triggered to write or delete a particular block from among the at least one block of the file system, allowing the file system to write to or delete the particular block without making a snapshot copy of the particular block if a particular entry for the particular block in the snapshot map specifies the particular block is newly allocated.

A system for managing a point in time snapshot of a file system, comprising:

a file system managed by at least one file handling thread comprising a plurality of blocks of an allocated portion of disk space of a computer system;
the at least one file handling thread for tracking a mapping of an allocation state of each of said plurality of blocks of the file system;
a point in time snapshot managed within the allocated portion of disk space by at least one snapshot thread;
the snapshot thread for tracking, for at least one block of the plurality of blocks of the file system, a separate entry in a snapshot map specifying if each at least one block is newly allocated following the creation of the snapshot and specifying an addressed location of a snapshot copy of the at least one block if copied within the snapshot;
and
the snapshot thread, responsive to detecting the file handling thread triggered to write or delete a particular block from among the at least one block of the file system, for allowing the file handling thread to write to or delete the particular block without making a snapshot copy of the particular block if a particular entry for the particular block in the snapshot map specifies the particular block is newly allocated.

3 more elements

A computer program product for managing a point in time snapshot of a file system stored within the space allocated to the file system, the computer program product residing on a computer readable medium, the computer readable medium comprising instructions which when executed on a computer system cause the computer system to perform the steps of:

tracking, for at least one block of the plurality of blocks of the file system, a separate entry in a snapshot map specifying if each at least one block is newly allocated following the creation of the point in time snapshot and specifying an addressed location of a snapshot copy of the at least one block if copied, separately from tracking a mapping of an allocation state of each of said plurality of blocks of the file system;
and
responsive to detecting the file system triggered to write or delete a particular block from among the at least one block of the file system, allowing the file system to write to or delete the particular block without making a snapshot copy of the particular block if a particular entry for the particular block in the snapshot map specifies the particular block is newly allocated.

Dependencies are inferred from the claim text.

Managing a snapshot stored within a file system space for efficient detecting of in-use blocks

Life of this patent

Managing a snapshot stored within a file system space for efficient detecting of in-use blocks

Life of this patent

Abstract

Claims19