US 6,633,891 B1 · Managing replacement of data in a cache on a node based on caches of other nodes

Abstract

A mechanism is described for managing the caches on nodes in a cluster. The caches are globally managed so that a data item may be retained in any cache on the nodes. This may be accomplished by, for example, a replacement policy for replacing data items stored in the buffers of the caches, where a buffer is selected for replacement in a manner that accounts for factors that include the state of the caches of other nodes. Some cached data items are designated as globally shared, and assigned (either statically or dynamically) a primary cache. For example, if a buffer holds a copy of a data item whose primary cache is another node, then the data item in the buffer is favored for replacement over a local data item or a global data item for which this is the primary cache. According to another aspect of the invention, the cache retention value of buffers on different nodes are compared, and the buffer with the lowest cache retention value is selected for replacement. According to yet another aspect of the present invention, the replacement policy accounts for the configuration of other caches in the cluster.

Claims30

Dependent claims

A method for managing replacement of data stored in buffers of a plurality of caches that each reside on a node of a set of one or more nodes, wherein each node of said set of one or more nodes includes one or more caches of said plurality of caches, wherein the plurality of caches includes a first cache, the method comprising the steps of:

from a plurality of buffers available for replacement in the first cache, selecting for replacement a first buffer from said first cache based on one or more factors, wherein said first buffer is currently used to store a first data item, wherein said one or more factors include either:
the state of at least one other cache of said plurality of caches, or the configuration of said at least one other cache of said plurality of caches;
replacing said first data item stored in said first buffer with a second data item;
transferring said first data item to another particular cache of said plurality of caches;
in response to transferring said first data item to the particular cache, generating data that indicates that said first buffer contains data that may be removed from said first cache;
and
wherein said one or more factors include that said data indicates that said first buffer contains data that may be replaced.

4 more elements

Dependencies are inferred from the claim text.

Managing replacement of data in a cache on a node based on caches of other nodes

Life of this patent

Managing replacement of data in a cache on a node based on caches of other nodes

Life of this patent

Abstract

Claims30