Abstract: The meta data containing count and key fields of CKD records are reversibly decoupled from the user data of the data field so that the data can be deduplicated. Multiple CKD records may be coalesced into a larger size CKD track. The coalesced meta data is compressed and stored in a CKD hash table. The user data is hashed, and the hash is used as a hash key that is associated with the compressed meta data in the CKD hash table. When the hash of user data associated with a CKD write IO matches the hash key of an existing entry in the table, data duplication is indicated. The compressed meta data is added to the entry and the user data is deduplicated by creating storage system meta data that points to the pre-existing copy of the user data. The storage system metadata includes unique information that enables the corresponding compressed metadata to be subsequently located in the hash table to reassemble the CKD records.

Abstract: The meta data containing count and key fields of CKD records are reversibly decoupled from the user data of the data field so that the data can be deduplicated. Multiple CKD records may be coalesced into a larger size CKD track. The coalesced meta data is compressed and stored in a CKD hash table. The user data is hashed, and the hash is used as a hash key that is associated with the compressed meta data in the CKD hash table. When the hash of user data associated with a CKD write IO matches the hash key of an existing entry in the table, data duplication is indicated. The compressed meta data is added to the entry and the user data is deduplicated by creating storage system meta data that points to the pre-existing copy of the user data. The storage system metadata includes unique information that enables the corresponding compressed metadata to be subsequently located in the hash table to reassemble the CKD records.

Abstract: Writing new data to a tape volume of a tape emulation unit includes determining if the new data is an update to data that was previously written, writing the new data to a new section of the tape emulation unit in response to the new data not updating data that was previously written, deleting the data that was previously written and writing the new data to a new section in response to the new data updating data that was previously written, the new data being larger than the data that was previously written, and the underlying file system not supporting variable size records/blocks, and overwriting the data that was previously written in response to the new data updating data that was previously written and either the new data not being larger than the data that was previously written or the underlying file system supporting variable size records/blocks.

Abstract: Writing new data to a tape volume of a tape emulation unit includes determining if the new data is an update to data that was previously written, writing the new data to a new section of the tape emulation unit in response to the new data not updating data that was previously written, deleting the data that was previously written and writing the new data to a new section in response to the new data updating data that was previously written, the new data being larger than the data that was previously written, and the underlying file system not supporting variable size records/blocks, and overwriting the data that was previously written in response to the new data updating data that was previously written and either the new data not being larger than the data that was previously written or the underlying file system supporting variable size records/blocks.

Abstract: Replicating data written to a local storage device from a host includes receiving the incoming data using a first director that mirrors the incoming data from the first director to a second director independently of any links that transmit data to or from the directors and other components of the local storage device and transmitting the mirrored data from the local storage device to a remote storage device. The first director may be a target device (e.g., FICON target) that accepts data and connection requests from the host. The second director may be an initiator device (e.g., FICON initiator) that provides data and connection requests to the remote storage device. The second director may emulate a FICON initiator. The local storage device may wait for an acknowledgement of receipt of the data from the remote storage device before acknowledging receipt to the host.