System and method for providing implicit unmaps in thinly provisioned virtual tape library systems

摘要

The present invention is a system and method which allows for a VTL system that supports thin provisioning to implicitly unmap unused storage. Such unmap operations may occur even though the VTL system does not receive any explicit unmap requests from its initiators. For example, if a system administrator knows that once a virtual tape drive of the VTL system has been partially overwritten, all previously written data sets on that virtual tape drive will never again be accessed, the system administrator may configure the VTL system so that it unmaps the entire remainder of the virtual tape drive on the first data overwrite.

主权项

1. A method for utilizing Small Computer System Interface (SCSI) commands in a virtual tape library (VTL) system, comprising:
writing a first data set to a first portion of Logical Block Addressing (LBA) space of a virtual tape drive of the VTL system; mapping the first portion of LBA space of the virtual tape drive to physical storage of the VTL system; writing a second data set to a second portion of the LBA space of the virtual tape drive of the VTL system; mapping the second portion of LBA space of the virtual tape drive to physical storage of the VTL system; writing a third data set to the first portion of LBA space, wherein writing the third data set to the first portion of LBA space includes overwriting at least a portion of the first data set at the first portion of LBA space without overwriting the second data set at the second portion of the LBA space; determining that the unoverwritten second data set at the second portion of LBA space is invalid when at least the portion of the first data set at the first portion of LBA space is overwritten; and responsive to determining that the second data set at the second portion of LBA space is invalid, implicitly unmapping the second portion of LBA space of the virtual tape drive from physical storage of the VTL system without receiving an explicit unmap command from an initiator that initiated the writing of the third data set at the first portion of LBA space.