Patent ID: 8700871
Filing Date: 2014-04-15
Classification: G06F

Abstract:
1. A method of controlling an information processing system including a first storage system that includes a first server apparatus and a first storage apparatus that is communicatively coupled with the first server apparatus, and a second storage system that includes a second server apparatus and a second storage apparatus that is communicatively coupled with the second server apparatus, the first storage system and the second storage system being communicatively coupled with each other, wherein the first storage apparatus provides a first logical volume to the first server apparatus, the second storage apparatus provides a second logical volume to the second server apparatus, the first storage system performs de-duplication of the data stored in the first logical storage by using a common entity as entities of data associated with an identifier that the first server apparatus specifies when accessing the first logical volume, the second storage system performs de-duplication of data stored in the second logical storage by using a common entity as entities of associated with an identifier that the second server apparatus specifies when accessing the second logical volume, the first server apparatus acquires a snapshot of a primary volume that is the first logical volume, the first server apparatus stores snapshot data including the primary volume and a differential volume that is the first logical volume in which differential data is stored when the primary volume is updated after the acquisition of the snapshot of the primary volume, the differential data being the data having been stored in the primary volume until the updating, the first server apparatus calculates first de-duplication efficiency which is de-duplication efficiency of the snapshot data, and second de-duplication efficiency which is de-duplication efficiency of snapshot entities that are created on the basis of the snapshot data, and the first server apparatus selects a method of migrating data related to the snapshot to the second storage system on the basis of a result obtained by comparing the first de-duplication efficiency with the second de-duplication efficiency, wherein the first server apparatus selects a first method as the migration method when the first de-duplication efficiency is lower than the second de-duplication efficiency, the first method being a method including creating a snapshot image that is data materialized from the snapshot, and migrating the created snapshot image to the second storage system, the first server apparatus stores a first preservation period which is set for the snapshot in the first storage system, and a second preservation period which is set for the snapshot in the second storage system, the first server apparatus selects a second method as the migration method when the first de-duplication efficiency is equal to or higher than the second de-duplication efficiency and also when the first preservation period is longer than the second preservation period, the second method being a method including migrating the snapshot data to the second storage system, the first server apparatus stores the first preservation period which is set for the snapshot in the first storage system, and the second preservation period which is set for the snapshot in the second storage system, when an allocatable capacity of the first differential volume reaches a predetermined threshold value or below, the first server apparatus switches a storage destination of the differential data to a second differential volume that is another first logical volume different from the first differential volume, the first server apparatus acquires a switch snapshot that is the snapshot of the primary volume at the time of the switching, the first server apparatus selects a third method as the migration method when the first de-duplication efficiency is equal to or higher than the second de-duplication efficiency and also when the first preservation period is equal to or shorter than the second preservation period, the third method being a method including migrating snapshot images that are data materialized from the first differential volume, the second differential volume, and the switch snapshot to the second storage system, the first storage system manages data in the first logical volume on a data block basis, the first de-duplication efficiency is a value obtained by calculation in which a sum of the number of data blocks of the primary volume and the number of data blocks of all the differential volumes is divided by a product of the number of data blocks of the primary volume and the number of all the acquired snapshots, the second storage system manages data in the second logical volume on a data block basis, the second de-duplication efficiency is a value obtained by calculation in which the number of data blocks used after snapshot images materialized from all the snapshot data are de-duplicated is divided by the number of data blocks used in a case where snapshot images materialized from all the snapshot data are not de-duplicated, the first server apparatus includes a file system in which data stored in the first logical volume is managed on a file basis, the second server apparatus includes a file system in which data stored in the second logical volume is managed on a file basis, the de-duplication in the first storage system is performed on a file basis; the de-duplication in the second storage system is performed on a file basis, the first storage apparatus stores data in the first logical volume on a data block basis; the snapshot data includes a snapshot management table for keeping information on whether CoW (Copy on Write) is needed or not for each data block, and upon acquiring the snapshot of the primary volume, the first storage apparatus sets, in the snapshot management table, information indicating that the CoW is needed for the data block, the first storage apparatus and the second storage apparatus each include a channel control unit that performs communication with a client apparatus which sends an I/O request, a drive control unit that writes data into a storage device and reads data from the storage device, a cache memory that stores therein data to be written into the storage device or data read from the storage device, and a processor control unit that performs data transfer between at least any two of the channel control unit, the drive control unit, and the cache memory.