Caching techniques

An apparatus comprising:

• a first data storage system including a first cache and a first device;
• a second data storage system including a second cache and a second device;
• and
• a non-transitory computer readable medium of executable code stored thereon for:
• determining, at a point in time, a first set of data portions currently stored in the first cache, each data portion of said first set being located on the first device;
• sending, from the first data storage system to the second data storage system, first information including information identifying a storage location on said first device for each data portion of said first set, wherein said second device is maintained as a mirror of the first device, said storage location for each data portion of said first set used to identify a second storage location of said second device corresponding to said storage location;
• and
• using said first information to populate the second cache of the second data storage system.

A non-transitory computer readable medium comprising code stored thereon for caching, the non-transitory computer readable medium comprising code for:

• determining, at a point in time, a first set of data portions currently stored in a first cache of a first data storage system, each data portion of said first set being located on a first device of the first data storage system;
• sending, to a second data storage system, first information including information identifying a storage location on said first device for each data portion of said first set, wherein said second data storage system includes a second device that is maintained as a mirror of the first device, said storage location for each data portion of said first set used to identify a second storage location of said second device corresponding to said storage location;
• and
• using said first information to populate a second cache of the second data storage system.