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A Method and System for Reducing Copy on Write Workload in a Tape Off-load Scenario

IP.com Disclosure Number: IPCOM000238323D
Publication Date: 2014-Aug-18
Document File: 3 page(s) / 91K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method and system is disclosed for reducing copy on write workload in a tape offload scenario.

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This is the abbreviated version, containing approximately 71% of the total text.

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A Method and System for Reducing Copy on Write Workload in a Tape Off-load Scenario Fig. 1 illustrates a standard environment used in a tape off-load scenario.

Figure 1

As shown in fig. 1, a FlashCopy* is created between the source volume set and the target volume set. Here, the FlashCopy is created in such a manner that it ensures that data off-loaded to the tape is consistent and the source volume is still accessible by the host. Typically the tape off-load process sequentially off-loads data from the starting address of the target volume. There exists a need to minimize impact to host Input / Output (I/O) due to collisions to a volume while a tape off-load completes.

Disclosed is a method and system for reducing copy on write workload in a tape off-load scenario.

The method and system reduces copy on write workload on a storage system in the tape off-load scenario by avoiding unnecessary I/O due to collisions from a FlashCopy source volume. The source volume includes a bitmap kept for the FlashCopy target that indicates if the data is off-loaded to a tape. If a host I/O occurs and a bit corresponding to the track is set in the bitmap, then the collision is ignored and there is no copy on write. If a host I/O occurs and bit corresponding to this track is not set, then

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the copy on write is performed as normal FlashCopy.

Fig. 2 illustrates a flowchart for executing an algorithm to minimize impact to host I/O due to collisions to the volume while t...