Warm start cache recovery in a dual active controller with cache coherency using stripe locks for implied storage volume reservations

A computer program product for maintaining cache coherency amongst a plurality of caching storage controllers in a data storage system during a warm start cache recovery, the computer program product including a computer readable medium and a computer mechanism stored thereon, the computer mechanism comprising instructions for:

• defining a stripe lock data structure to maintain reservation status (stripe lock) of cache lines within data extents that are part of a logical unit or storage volume;
• storing stripe lock data structure information and cache line data of each of the plurality of caching storage controllers during a power failure;
• and
• using the stripe lock data structure to minimize a delay required for continued processing of I/O requests from one or more host computers following the warm start cache recovery.

In a data storage system having a plurality of storage controllers, a method of maintaining cache coherency amongst said storage controllers during a warm start cache recovery, the method comprising steps of:

• defining a stripe lock data structure in a memory to maintain reservation status or stripe locks of cache lines within data extents that are part of a logical unit or storage volume;
• storing the stripe lock data structure and cache line data of at least one of said plurality of caching storage controllers during a power failure;
• and
• using information stored in the stripe lock data structure to minimize delay in continued processing of input/output requests from a host computer coupled to said data storage system following a warm start cache recovery.

A method for using a caching storage controller device, the method comprising steps of:

• defining a stripe lock data structure in a memory of the caching storage controller to maintain reservation status or stripe locks of cache lines within data extents that are part of a logical unit or storage volume shared by a plurality of caching storage controller devices;
• storing, by a battery backup unit (BBU), the stripe lock data structure and cache line data of each of the plurality of caching storage controllers during a power failure;
• and
• using the stripe lock data structure to minimize a delay required for continued processing of I/O requests from one or more host computers following the warm start cache recovery.