Disclosed are methods and apparatus for data tapping within a storage area network (SAN) and providing tapped data to a third party device, such as an appliance. In general, mechanisms are provided in a SAN to allow a data tap of data flowing between an initiator and a target. In one implementation, a data virtual target (DVT) in created in a network device to intercept data sent by a specific initiator to a specific logical unit of a specific target. The data or a copy of the data is sent to both the specific logical unit of the specific target and to an appliance. The data routing may be accomplished by use of a virtual initiator (VI), which is configured to send the data (or a copy of the data) to the specific target and the appliance. In a transparent mode of operations, the DVT has a same PWWN (port world wide name) and FCID (fibre channel identifier) as the specific target. In a first proxy mode of operation, the DVT has a different PWWN and FCID than the specific target. In a second proxy mode of operation, the DVT has a same PWWN and different FCID than the specific target.

Disclosed is apparatus and methods for enabling an appliance to receive data being sent between any host of a host cluster to a specified storage device's logical unit (LUN) in a single stream or session. In one embodiment, a data virtual target is initially set up for a specified storage device LUN so that data written from a host to the specified storage device LUN is received by the DVT. An appliance then sends a session request to mirror data that is sent to the DVT (and specified storage device LUN) to a specified LUN of the appliance. The session request is not host specific. That is, data that is sent by any host to the DVT is mirrored to the same appliance LUN.

The present invention extends to methods, systems, and computer program products for extending non-volatile storage at a computer system. In some embodiments, a file operation is performed on at least one shadow copy of a file that is perceived by an application to be stored on a single volume. A plurality of shadow copies of a file can be accessed using durable file identifiers that are durable across changes to other file characteristics. It is indicated back to the application that the file operation was performed on the file perceived to be stored on the single volume. Storage capabilities are enhanced through migration and/or replication of files to newly added volumes.

Disclosed are apparatus and methods for facilitating caching in a storage area network (SAN). In general, data transfer traffic between one or more hosts and one or more memory portions in one or more storage device(s) is redirected to one or more cache modules. One or more network devices (e.g., switches) of the SAN can be configured to redirect data transfer for a particular memory portion of one or more storage device(s) to a particular cache module. As needed, data transfer traffic for any number of memory portions and storage devices can be identified for or removed from being redirected to a particular cache module. Also, any number of cache modules can be utilized for receiving redirected traffic so that such redirected traffic is divided among such cache modules in any suitable proportion for enhanced flexibility.