Tracking block-level changes using snapshots
First Claim
1. A method of updating a backup storage volume with incremental changes made to a source storage volume, comprising:
- generating a first snapshot of the source storage volume at or before the beginning of a prior backup cycle and maintaining the first snapshot through a current backup cycle;
at the beginning of the current backup cycle, generating a second snapshot of the source storage volume and then examining a dirty block list of the first snapshot to identify a set of blocks of the source storage volume that have changed during a time period the first snapshot is maintained, the set of blocks including at least those blocks that have changed between the beginning of the prior backup cycle and the beginning of the current backup cycle; and
copying the changed blocks into the backup storage volume using the second snapshot.
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Accused Products
Abstract
Writes to blocks of a protected storage volume that occur between the beginning of a prior backup interval and the beginning of a current backup interval are tracked using a first snapshot that is maintained through the current backup interval. At the beginning of the current backup interval, a second snapshot is generated. Blocks that are indicated by a dirty block list of the first snapshot as having been changed are read from the snapshot volume for the second snapshot and copied to a backup storage volume. For the next backup interval, the second snapshot or alternatively, a newly generated third snapshot, is used to track writes to blocks of a protected storage volume that occur between the beginning of the current backup interval and the beginning of a next backup interval.
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Citations
24 Claims
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1. A method of updating a backup storage volume with incremental changes made to a source storage volume, comprising:
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generating a first snapshot of the source storage volume at or before the beginning of a prior backup cycle and maintaining the first snapshot through a current backup cycle; at the beginning of the current backup cycle, generating a second snapshot of the source storage volume and then examining a dirty block list of the first snapshot to identify a set of blocks of the source storage volume that have changed during a time period the first snapshot is maintained, the set of blocks including at least those blocks that have changed between the beginning of the prior backup cycle and the beginning of the current backup cycle; and copying the changed blocks into the backup storage volume using the second snapshot. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A computer-readable storage medium containing instructions for causing a computer system to carry out a method of incrementally updating a backup storage volume with changes made to a source storage volume, the method comprising the steps of:
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generating a first snapshot of the source storage volume at or before the beginning of a prior backup cycle and maintaining the first snapshot through a current backup cycle; at the beginning of the current backup cycle, generating a second snapshot of the source storage volume and then examining a dirty block list of the first snapshot to identify a set of blocks of the source storage volume that have changed during a time period the first snapshot is maintained, the set of blocks including at least those blocks that have changed between the beginning of the prior backup cycle and the beginning of the current backup cycle; and copying the changed blocks into the backup storage volume using the second snapshot. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A computer system for tracking changes made to a source storage volume that is being backed up by a backup storage volume, comprising a processing unit that is programmed to:
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generate a first snapshot of the source storage volume at or before the beginning of a prior backup cycle and maintain the first snapshot through a current backup cycle; at the beginning of the current backup cycle, generate a second snapshot of the source storage volume and then examine a dirty block list of the first snapshot to identify a set of blocks of the source storage volume that have changed during a time period the first snapshot is maintained, the set of blocks including at least those blocks that have changed between the beginning of the prior backup cycle and the beginning of the current backup cycle; and copy the changed blocks into the backup storage volume using the second snapshot. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification