Method and system for coherently caching I/O devices across a network

Abstract

The cache keeps regularly accessed disk I/O data within RAM that forms part of a computer systems main memory. The cache operates across a network of computers systems, maintaining cache coherency for the disk I/O devices that are shared by the multiple computer systems within that network. Read access for disk I/O data that is contained within the RAM is returned much faster than would occur if the disk I/O device was accessed directly. The data is held in one of three areas of the RAM for the cache, dependent on the size of the I/O access. The total RAM containing the three areas for the cache does not occupy a fixed amount of a computers main memory. The RAM for the cache grows to contain more disk I/O data on demand and shrinks when more of the main memory is required by the computer system for other uses. The user of the cache is allowed to specify which size of I/O access is allocated to the three areas for the RAM, along with a limit for the total amount of main memory that will be used by the cache at any one time.

1 . A caching system comprising: 
 a network;    a plurality of computers interacting on the network, each computer having a memory;    cache software resident on each of the computers participating in the caching method;    said cache software being configured to cache data from selected ones of the I/O devices;    wherein said cache software is informed of all other cache software that permits caching of the selected I/O devices;    and wherein the cache software includes:    remote messaging code that forms a computer communication channel with the cache software on any of said computers for sending messages related to caching, wherein said remote messaging code saves a remote connection address for each of the communication channels; and    listening code that listens on said network for a request for a computer to connect to said network.