Achieving data consistency with point-in-time copy operations in a parallel I/O environment
View Patent ↗A method for processing a point-in-time copy of data associated with a logical storage volume where the data to be copied is stored in a striped or parallelized fashion across more than one physical source volume. The method includes receiving a point-in-time copy command concerning a logical volume and distributing the point-in-time copy command in-band to each of the physical source volumes containing a portion of the striped data. The method also includes establishing a point-in-time copy relationship between each physical source volume and one of a corresponding set of multiple physical target volumes. The method further includes copying the data stored on each physical source volume to the corresponding physical target volume. The in-band copy command and the striped data may be distributed over I/O channels between a server and the physical storage and processed sequentially.
1. A method of processing a point-in-time copy of data associated with a logical storage volume, the method comprising:
receiving first data associated with a logical volume;
sending the first data over I/O channels in a striped fashion for storage across more than one physical source volume;
storing the first data on the more than one physical source volume;
receiving a first point-in-time copy command concerning the first data;
distributing the first point-in-time copy command over the I/O channels to each of the physical source volumes;
establishing a point-in-time copy relationship between each physical source volume and a corresponding one of a set of more than one physical target volumes;
receiving second data associated with the logical volume to update the first data;
sending the second data over the I/O channels in a striped fashion for storage across the more than one physical source volume;
executing the distributed first point-in-time copy command by copying the first data stored on each physical source volume to the corresponding physical target volume; and
storing the second data on a physical source volume after the first data has been copied to the corresponding physical target volume.
2. The method of claim 1 , wherein the I/O channels comprise in-band I/O channels maintained between a storage controller and the physical source volumes and across which read and write I/O operations are distributed.
3. The method of claim 1 further comprising:
receiving multiple updates to the first data associated with the logical volume;
receiving multiple point-in-time copy commands concerning the multiple updates, with the multiple point-in-time copy commands and multiple updates being received in a sequence;
parallelizing the updates;
distributing the updates to each of the physical source volumes;
distributing the point-in-time copy commands to each of the physical source volumes; and
writing the updates to each physical source volume and executing the point-in-time copy commands with respect to each physical source volume in accordance with the sequence, whereby an update is stored to a physical source volume only after a previous update is copied from the physical source volume to the corresponding physical target volume.