Mechanisms and techniques disclose a system that provides access to data
using a two part cache. The system receives a data access request containing a
first data reference, such as an open systems request to access data. The system
then obtains a history cache entry from a history cache based on the first data
reference and obtains a partition cache entry from a partition cache based on the
first data reference. Cache entries contain mappings between open systems reference
locations and non-open systems references to locations in the data to be accessed.
The system then performs a data access operation as specified by the data access
request using a second data reference based upon either the history cache entry
or the partition cache entry. Upon performance of the data access operation, the
system then updates the history and partition caches with new cache entries and
can resize the partition and history caches as needed.
