Cache memory arrangement and methods for use in a cache memory system

TLDR: In this paper, a cache memory system to support re-synchronisation of non-volatile cache memories following interruption in communication is presented, where the data to be transferred represents only the transactions which were in progress at the time of the reset or failure, rather than the entire non-vatile cache contents.

Abstract: An arrangement and methods for operation in a cache memory system to facitate re-synchronising non-volatile cache memories (150B, 160B) following interruption in communication. A primary adapter (150) creates a non-volatile record (150C) of each cache update before it is applied to either cache. Each such record is cleared when the primary adapter knows that the cache update has been applied to both adapters' caches. In the event of a reset or other failure, the primary adapter can read the non-volatile list of transfers which were ongoing. For each entry in this list, the primary adapter negotiates with the secondary adapter (160) and transfers only the data which may be different. The amount of data to be transferred between the adapters following reset/failure is generally much lower than under previous solutions, since the data to be transferred represents only the transactions which were in progress at the time of the reset or failure, rather than the entire non-volatile cache contents; also, new transactions need not be suspended while even this reduced resynchronisation takes place: all that is necessary is for the (relatively short) list of in-doubt quanta of data to be searched (if the transaction does not overlap any entries in this list then it need not be suspended; if it does overlap then the transaction may be queued until the resynchronisation completes).