The assignee for this patent, patent number 8745344, is
Reporters obtained the following quote from the background information supplied by the inventors: "As the virtualization technique for computer resources improves, a server virtualization which enables a plurality of virtual machines operated on a single physical server to concurrently execute a plurality of tasks is being used widely. Similarly, a capacity virtualization is widely being used, in which when an external apparatus such as a host computer demands a data storing area, unit physical storage areas are provided from a pool consisting of a plurality of the unit physical storage areas, each of which being created by dividing a physical storage area of a storage device. This capacity virtualization is generally known as a 'thin provisioning.'
"The virtual machine of the server virtualization each uses a logical volume (Logical Unit, LU) as a dedicated logical storage area for a data storage area. Such a configuration is usually employed that, where a snapshot pair is created with two LUs, a primary volume (PVOL) and a secondary volume (SVOL), the SVOL is assigned to the LU for the virtual machine. In this configuration, not an ordinary LU but a virtual volume (VVOL) is usually used for the SVOL. The VVOL is constructed from data stored in a PVOL and difference data from the data in the PVOL. When the VVOL is used for a data storage area of the virtual machine, the LU is not necessarily provided to each virtual machine and the storage device is efficiently utilized. The difference data is stored in an LU dedicated for storing only the difference data. A snapshot pair of the PVOL and the VVOL is created for each virtual machine and the snapshot pair is subject to a split status, then the VVOL can be used for a data storage area of the virtual machine to which the above VVOL is assigned. Using the function of the snapshot pair, data processing such as backup and restoration of data can be timely carried out.
"In order to apply the snapshot function effectively, the technique disclosed, for example, in PTL 1 is proposed. PTL 1 discloses, for example, a storage system having a physical snapshot executing part writing updated data into both a primary storage device and a secondary storage device, a logical snapshot executing part writing input data into the primary storage device and difference data of difference between the input data and data prior to update into the secondary storage device, an update data determination part that, when creation of snapshot data is requested by an upper apparatus, determines whether or not there exist data to be updated in the primary storage device with respect to the creation request, a data update amount determination part that when the update data determination part detects presence of the updated data in the primary storage device, determines whether or not the data update amount in the primary storage device is larger than a predetermined amount, and a snapshot executing part selector that, when the data update amount determination part determines the data update amount in the primary storage device is larger than the predetermined amount, selectively drives the physical snapshot executing part, and, when the data update amount determination part determines the data update amount in the primary storage device is smaller than the predetermined amount or the data to be updated does not exist in the primary storage device, selectively drives the logical snapshot executing part. PTL 1 describes when creating snapshot data in the storage system, it can be prevented that a data space for saving data prior to update is filled with saved data from the primary (logical) volume and the process of creation of the snapshot data is abnormally aborted."
In addition to obtaining background information on this patent, VerticalNews editors also obtained the inventors' summary information for this patent: "Technical Problem
"However, in PTL 1, there is not disclosed a configuration in which a thin provisioning technique is applied to the snapshot function which is referred to as a logical snapshot function or a quick shadow function in PTL 1 to enable efficient utilization of storage resources. PTL 1 does not disclose a technique for improvement of an access rate when accessing the VVOL by an external apparatus in the configuration that a VVOL is used for an SVOL of a snapshot pair, either.
"The present invention has been made in order to solve the above and other problems, and an object thereof is to provide a storage system with a function of enabling creating a snapshot pair easily while efficiently utilizing storage resources by employing a thin provisioning and a controlling method of the same. Another object of the present invention is to provide a storage system enabling improvement of an access rate in accessing an SVOL in a snapshot pair created with the thin provisioning and a controlling method of the same.
"Solution to Problem
"One aspect of the present invention for achieving the above and other objects is a storage system comprising a storage device from which a physical storage area is created, the physical storage area being for providing a logical storage area storing data processed in an external apparatus, a thin provisioning controller creating a plurality of unit physical storage areas from the physical storage area of the storage device, creating a physical storage area pool as a set of the unit physical storage areas, and creating a logical volume as a unit logical storage area having a part of the unit physical storage areas included in the physical storage area pool, and a snapshot controller designating the logical volume as a primary volume, defining a secondary volume which is a partner of data copy including a data backup for the primary volume as a combined data of the data stored in the primary volume and difference data which is data different from the stored data in the primary volume, assigning unused one of the unit physical storage areas in the physical storage area pool as an area into which the difference data is to be stored, and setting a volume pair created with the primary volume and the secondary volume into a synchronizing state where the data stored in the primary volume and the data stored in the secondary volume are synchronized and a non-synchronizing state where the data stored in the primary volume and the data stored in the secondary volume are not synchronized.
"Another aspect of the present invention is the above-mentioned storage system further comprising a primary volume data temporary storing area being a storage area for storing data read from the primary volume temporarily, and a pool data temporary storing area being a storage area for storing data to be written into the physical storage area pool, the storage system, when receiving a data write request for the secondary volume from the external apparatus, determining whether or not the data to be written in the data write request includes corresponding difference data, if it is determined that the data to be written in the data write request does not include corresponding difference data, when the data to be written is stored into the pool data temporary storing area, transmitting to the external apparatus information indicating that processing of the data write request is completed, reading primary volume data stored in a storage area including the data to be written from the primary volume and storing the primary volume data as read into the primary volume data temporary storing area, combining the primary volume data as read with the data to be written in the pool data temporary storing area, and storing the data as combined into the physical storage area pool.
"Advantageous Effects of Invention
"According to one aspect of the present invention, a storage system with a function of enabling creating a snapshot pair easily while efficiently utilizing storage resources by employing a thin provisioning and a controlling method of the same are provided. According to another aspect of the present invention, a storage system enabling improvement of an access rate in accessing an SVOL in a snapshot pair created with the thin provisioning and a controlling method of the same are provided."
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