摘要:
A storage system and method for prestaging data in a cache based on relative changes in the frequency of data access and relative changes in the effectiveness of previous prestage operations. The relative changes in the frequency of data access are determined by storing statistics of data access to all regions in the system and comparing recent access statistics to the stored data. Access statistics include data location, I/O size and access frequency. The relative changes in the effectiveness of previous prestage operations are detected by recording the number of previous prestaging operations for a region, recording the number of I/O requests for data that has been prestaged, and dividing the number of I/O requests for previously prestaged data in a region during a time period by the number of previous prestage operations for the region during the same time.
摘要:
Disclosed is a system, method, and program storage device implanting the method for revising a software application wherein the software application utilizes persistent data, comprising applying an upgrade to a first next level of software that understands both old and new persistent data structure formats; converting all persistent data structures into the old persistent data structure format; applying an upgrade to a second next level of software that understands the old and new persistent data structure formats; converting all persistent data structures into the new persistent data structure format; applying a downgrade to a first previous level of software that understands both the old and new persistent data structure formats; converting all persistent data structures into the old persistent data structure format; and applying a downgrade to a second previous level of software that understands the old persistent data structure formats.