Abstract: In one aspect, a method includes receiving, at a storage array, a command to a virtual volume from a host, extracting a virtual volume index from the command; reading a table using the virtual volume index to determine the logical unit where the virtual volume is stored and executing the command at the logical unit with the virtual volume. The command is one of a read command to read data from the virtual volume or a write command to write data to the virtual volume.

Abstract: A data storage system provides asymmetric multi-path access to a storage device from a host computer using a storage protocol such as SCSI. Device state information is maintained indicating that one path of set of paths between the host computer and the storage device is a non-fully-functional path. In response to receiving device discovery commands from the host computer on the one path and the one path being indicated to be a non-fully-functional path, the data storage system returns respective good responses indicating that the storage device is accessible to the host computer via the non-fully-functional path. However, in response to receiving a test unit readiness command from the host computer on the one path and the one path being indicated to be a non-fully-functional path, an error response is returned which causes the host computer to select an alternative path of the set of paths for the data transfer.

Abstract: In one aspect, a method includes receiving, at a storage array, a command to a virtual volume from a host, extracting a virtual volume index from the command; reading a table using the virtual volume index to determine the logical unit where the virtual volume is stored and executing the command at the logical unit with the virtual volume. The command is one of a read command to read data from the virtual volume or a write command to write data to the virtual volume.