Patent ID: 8943286
Filing Date: 2015-01-27
Classification: G06F

Abstract:
1. A storage system comprising: a first storage apparatus, including a first logical volume, coupled to a host computer; and a second storage apparatus, including a second logical volume, coupled to the host computer and the first storage apparatus, wherein the first logical volume and the second logical volume are operated as a high availability (HA) pair in which data in the first logical volume is duplicated in the second logical volume, a virtual storage identifier is associated with both the first storage apparatus and the second storage apparatus, and a virtual volume identifier is associated with both the first logical volume and the second logical volume, so that the first storage apparatus or the second storage apparatus is capable to receive an access request to a virtual volume identified by the virtual storage identifier and the virtual volume identifier, wherein, when either the first storage apparatus or the second storage apparatus receives a write request to the virtual volume from the host computer, the storage system is configured to: lock a storage area, regarding the write request, in the first logical volume of the HA pair for writing data in the virtual volume; write data, regarding the write request, in the first logical volume and write data, regarding the write request in the second logical volume after completion of writing data in the first logical volume; and release the lock of the storage area of the first logical volume after writing data in both the first logical volume and the second logical volume; wherein, when the first storage apparatus receives a read request to the virtual volume from the host computer, the first storage apparatus is configured to: determine whether a first storage area of the first logical volume regarding the read request is locked; when the first storage area is locked, wait for release of the lock of the first storage area, read data regarding the read request from the first storage area of the first logical volume, and return a response to the host computer; and when the first storage area is not locked, read data regarding the read request from the first storage area of the first logical volume, and return a response to the host computer; and wherein, when the second storage apparatus receives a read request to the virtual volume from the host computer, the second storage apparatus is configured to: read data regarding the read request from a second storage area of the second logical volume without determining whether the second storage area regarding the read request is locked, and return a response to the host computer.