Method and apparatus for de-duplication after mirror operation
First Claim
1. A method of operating an information system, comprising:
- storing data to a first storage volume and mirroring the data to a second storage volume, said second storage volume being a virtual volume having a plurality of logical storage addresses, wherein a segment of physical storage capacity is allocated for a specified logical address as required when the data is to be stored to said specified logical address;
selecting segments of the second volume during a de-duplication operation on the second volume;
calculating a hash value for a particular segment representative of the data contained in the particular segment;
comparing the calculated hash value with previously-stored hash values for other segments in the second volume;
linking the particular segment to another segment having a previously-stored hash value that matches the calculated hash value of the particular segment; and
releasing the particular segment from the second volume when another segment has a previously-stored hash value that matches the calculated hash value of the particular segment, whereby physical storage capacity required for the second volume is reduced.
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Accused Products
Abstract
An amount of storage capacity used during mirroring operations is reduced by applying de-duplication operations to the mirror volumes. Data stored to a first volume is mirrored to a second volume. The second volume is a virtual volume having a plurality of logical addresses, such that segments of physical storage capacity are allocated for a specified logical address as needed when data is stored to the specified logical address. A de-duplication operation is carried out on the second volume following a split from the first volume. A particular segment of the second volume is identified as having data that is the same as another segment in the second volume or in the same consistency group. A link is created from the particular segment to the other segment and the particular segment is released from the second volume so that physical storage capacity required for the second volume is reduced.
194 Citations
20 Claims
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1. A method of operating an information system, comprising:
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storing data to a first storage volume and mirroring the data to a second storage volume, said second storage volume being a virtual volume having a plurality of logical storage addresses, wherein a segment of physical storage capacity is allocated for a specified logical address as required when the data is to be stored to said specified logical address; selecting segments of the second volume during a de-duplication operation on the second volume; calculating a hash value for a particular segment representative of the data contained in the particular segment; comparing the calculated hash value with previously-stored hash values for other segments in the second volume; linking the particular segment to another segment having a previously-stored hash value that matches the calculated hash value of the particular segment; and releasing the particular segment from the second volume when another segment has a previously-stored hash value that matches the calculated hash value of the particular segment, whereby physical storage capacity required for the second volume is reduced. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An information system, comprising:
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a first storage system including a first controller and a plurality of storage devices, said first controller configured to present physical storage space on said disks as volumes for storage of data; and a first host computer able to communicate with said first storage system via a network, wherein said first storage system is configured to store write data received from said computer to a first storage volume on said first storage system and mirror the write data to a second storage volume, said second storage volume being a virtual volume having a plurality of logical addresses, wherein segments of physical storage capacity are allocated for a logical address as required when the data is stored to said logical address; wherein said second volume is de-duplicated by selecting segments of the second volume during a de-duplication operation and a hash value is calculated for a particular segment representative of the data contained in the particular segment; wherein said calculated hash value is compared with previously-stored hash values for other segments in the second volume, and the particular segment is linked to another segment having a previously-stored hash value that matches the calculated hash value of the particular segment, wherein the particular segment is released from the second volume when another segment has a previously-stored hash value that matches the calculated hash value of the particular segment, whereby physical storage capacity required for the second volume is reduced. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method of reducing an amount of storage capacity used during mirroring operations, comprising:
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storing data to a first storage volume and mirroring the data to a second storage volume, said second storage volume being a virtual volume having a plurality of logical addresses, wherein segments of physical storage capacity are allocated for a specified logical address as required when the data is to be stored to said specified logical address; and carrying out a de-duplication operation on the second volume following a split from the first volume by; identifying a particular segment of said second volume having data that is the same as another segment; creating a link from the particular segment to the other segment; and releasing the particular segment from the second volume, whereby physical storage capacity required for the second volume is reduced. - View Dependent Claims (18, 19, 20)
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Specification