Disk apparatus, data replicating method onto disk apparatus and program recording medium
AssigneeNEC Corporation
InventorsTOMOKA KAMIURA, Kazuyuki Nagumo
Life of this patent
Estimating the term…
Abstract
A disk apparatus includes a second volume to which data of a first volume is copied, a third volume which stores a snapshot of the first volume, and an I/O processing unit which reads out data from the third volume when data of an area in which difference data exists in the third volume is read out, when data of an address in which the difference data does not exist in the third volume is read out, reads out data from the first volume if data copying from the first volume to the second volume has not been completed, and reads out data from the second volume if the data copying has been completed.
Claims10
A disk apparatus comprising:
- a second volume to which data of a first volume is copied;
- a third volume which stores a snapshot of said first volume, and stores a copy of difference data between data of said first volume after finishing writing of data to said first volume and data of said first volume before writing of the data;
- and
- an I/O processing unit which reads out data from said third volume when data of an area in which said difference data exists in said third volume is read out by a host, and when data of an area in which said difference data does not exist in said third volume is read out by said host, reads out data from said first volume if data copying from said first volume to said second volume has not been completed, and reads out data from said second volume if the data copying has been completed.
A non-transitory computer-readable recording medium having embodied thereon a computer program of data replication onto a disk apparatus, which when executed by a computer, causes the computer to execute steps of:
- an I/O processing step for
- storing a snapshot of a first volume, and reading out data from a third volume, which stores a copy of difference data between data of said first volume after finishing writing of data to said first volume and data of said first volume before writing of the data, when data of an area in which said difference data exists in said third volume is read out by a host;
- reading out data from said first volume when data of an area in which said difference data does not exist in said third volume is read out by said host, if data copying from said first volume to said second volume has not been completed;
- and
- reading out data from said second volume, if the data copying which copies data of said first volume to said second volume has been completed.
A data replicating method comprising:
- storing a snapshot of a first volume, and reading out data from a third volume, which stores a copy of difference data between data of said first volume after finishing writing of data to said first volume and data of said first volume before writing the data, when data of an area in which said difference data exists in said third volume is read out by a host;
- reading out data from said first volume when data of an area in which said difference data does not exist in said third volume is read out by said host, if data copying from said first volume to said second volume has not been completed;
- and
- reading out data from said second volume, if the data copying which copies data of said first volume to said second volume has been completed.
Dependencies are inferred from the claim text.