Techniques for performing data migration

A non-transitory computer readable medium comprising code stored thereon for migrating data from a source device of a source data storage system to a target device of a target data storage system, the non-transitory computer readable medium comprising code for:

• configuring the target data storage system to operate in accordance with a spoofing mode and a pass-through mode for the target device, wherein the spoofing mode causes the target data storage system to represent the target device to a host as the source device of the source data storage system, wherein the source device is accessible to the host on a first path between the host and the source data storage system and the target device is accessible to the host on a second path between the host and the target data storage system and wherein the host identifies the first path and the second path as alternate paths to the source device;
• processing a first set of commands from the host which are not user-data commands and which are received at the target data storage system for the target device when in the pass-through mode and the spoofing mode with respect to the target device, wherein processing each command of the first set of commands includes forwarding said each command of the first set to the source data storage system for processing and storing said each command of the first set and associated response as determined by the source data storage system in a cache at the target data storage system, and returning the associated response to the host, wherein when in the pass-through mode for the target device and prior to migrating data from the source device to the target device, first processing is performed for user-data commands, said first processing including:
• forwarding, from the target data storage system to the source data storage system for processing, all user-data commands directed to the target device represented as the source device;
• and
• returning, from the source data storage system to the target data storage system, user data in connection with servicing the user-data commands forwarded, and wherein the target data storage system does not store the user data, that is returned from the source data storage system to the target data storage system in said returning, for use in servicing subsequent user data commands;
• migrating data from the source device to the target device;
• configuring the target data storage system to operate in an echo mode for the target device after the migration of data from the source device to the target device is completed;
• and
• processing a second set of commands from the host received at the target data storage system when in the spoofing mode and when in the echo mode for the target device, wherein the second set of commands are not user-data commands and are directed to the target device represented to the host as the source device, wherein processing each of the second set of commands includes the target data storage system using information stored in the cache from processing the first set of commands for responding to said each of the second set of commands.