Techniques for inter-storage-processor cache communication using tokens

摘要

A method, performed at a first storage processor (SP) connected to a mirroring second SP, includes (a) receiving a write command at the first SP from a host directed to a particular address of a data storage array, (b) identifying a reference in a first cache that is uniquely associated with the particular address, the reference having a token count field, (c) determining whether the reference is synchronized with a corresponding reference in a second cache, and (d) if the reference is synchronized with the corresponding reference, then (1) performing a cache write operation on a cache page pointed to by the reference if the reference stores a maximum token count value and (2) otherwise, sending a token request message from the first SP to the second SP over a cache mirroring bus to request a token from the second SP prior to performing the cache write operation.

主权项

1. A method performed at a first storage processing device (SP), the first SP having a first cache, the first SP being communicatively connected to a second SP having a second cache over a cache mirroring bus, the first cache and the second cache being configured to function as mirrors, the first SP and the second SP being configured to operate in an active/active fashion for processing data storage commands directed at a data storage array, wherein the method comprises:
receiving a write command at the first SP from a host computer directed to a particular address of the data storage array; identifying a reference structure in the first cache that is uniquely associated with the particular address, the reference structure pointing to a set of cache pages associated with the particular address, the reference structure having a token count field; determining whether the reference structure is synchronized with a corresponding reference structure in the second cache; if the reference structure is synchronized with the corresponding reference structure, then:
performing a cache write operation on a cache page of the set of cache pages pointed to by the reference structure if the reference structure stores a maximum token count value; andotherwise, sending a token request message from the first SP to the second SP over the cache mirroring bus to request a token from the second SP prior to performing the cache write operation; if the reference structure is not synchronized with the corresponding reference structure, then:
performing the cache write operation if the reference structure stores a token count value of least one; andotherwise, sending a token request message from the first SP to the second SP over the cache mirroring bus to request a token from the second SP prior to performing the cache write operation; and in response to performing the cache write operation, synchronizing the reference structure with the corresponding reference structure by sending a merge message from the first SP to the second SP over the cache mirroring bus, the merge message including the cache page on which the cache write operation was performed to be copied to the second cache.