Method and apparatus for backup and recovery system using storage based journaling
First Claim
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1. A storage system coupled to a host computer via a network comprising:
- a data volume storing write data from the host computer;
a snapshot storing area storing a first snapshot of at least a portion of the data volume at a first point in time and also storing a second snapshot of said at least a portion of the data volume at a second point in time subsequent to the first point in time;
a journal storing area storing journal entries including a journal entry between the first point in time and the second point in time; and
a storage controller to conduct write operations according to write requests received from the host computer and to manage snapshot operations to store a plurality of snapshots including the first snapshot and the second snapshot,wherein when receiving a data recovery request with a target time between the first point in time and the second point in time, the storage system selects the first snapshot based on the target time, selects at least one of the journal entries corresponding to the write operation conducted between the first point in time and the target time, and recovers data of the portion of the data volume at the target time by using the first snapshot and a portion of at least one of the journal entries selected,wherein the storage system manages journal operations to record the journal entries, monitors the journal storing area based on a predetermined criterion, and releases at least one of the stored journal entries prior to the second point in time when the predetermined criterion is met, andwherein the second snapshot is taken at the second point in time independently of when the at least one of the stored journal entries is released.
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Abstract
A storage system maintains a journal of journal entries and at lease one snapshot of one or more data volumes. By assigning a unique sequence number to journal and snapshot, it is easy to find a journal which can be applied to the snapshot. A technique is described for detecting an overflow condition of running out of journal space and recovering the journal space.
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Citations
20 Claims
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1. A storage system coupled to a host computer via a network comprising:
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a data volume storing write data from the host computer; a snapshot storing area storing a first snapshot of at least a portion of the data volume at a first point in time and also storing a second snapshot of said at least a portion of the data volume at a second point in time subsequent to the first point in time; a journal storing area storing journal entries including a journal entry between the first point in time and the second point in time; and a storage controller to conduct write operations according to write requests received from the host computer and to manage snapshot operations to store a plurality of snapshots including the first snapshot and the second snapshot, wherein when receiving a data recovery request with a target time between the first point in time and the second point in time, the storage system selects the first snapshot based on the target time, selects at least one of the journal entries corresponding to the write operation conducted between the first point in time and the target time, and recovers data of the portion of the data volume at the target time by using the first snapshot and a portion of at least one of the journal entries selected, wherein the storage system manages journal operations to record the journal entries, monitors the journal storing area based on a predetermined criterion, and releases at least one of the stored journal entries prior to the second point in time when the predetermined criterion is met, and wherein the second snapshot is taken at the second point in time independently of when the at least one of the stored journal entries is released. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for storing information on a storage system coupled to a host computer via a network, the method comprising:
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conducting a write request received from a host computer, the write request including write data associated therewith to be stored on a data volume; storing journal data corresponding to the write data stored to the data volume from the host computer, in a journal storing area; storing a first snapshot of at least a portion of the data volume at a first point in time; and storing a second snapshot of the portion of the data volume at a second point in time; wherein when receiving a data recovery request with a target time between the first point in time and the second point in time, the storage system selects the first snapshot based on the target time, selects at least one of the journal data corresponding to the write request conducted between the first point in time and the target time, and recovers data of the portion of the data volume at the target time by using the first snapshot and a portion of at least one of the journal data selected, wherein the storage system manages journal operations to record the journal data, monitors the journal storing area based on a predetermined criterion, and releases at least one of the stored journal data prior to the second point in time when the predetermined criterion is met, and wherein the second snapshot is taken at the second point in time independently of when the at least one of the stored journal entries is released. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification