A synchronization confirmation method required for operation of a database is provided to a host device connected to a disk device which provides remote asynchronous data transfer. Immediately after commit of write data, an application of the host device issues a sync command which requires synchronization...http://www.google.com/patents/US6904503?utm_source=gb-gplus-sharePatent US6904503 - Storage system making possible data synchronization confirmation at time of asynchronous remote copy
