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17.3. Shared Cache Stores
A shared cache store is a cache store that is shared by multiple cache instances.
A shared cache store is useful when all instances in a cluster communicate with the same remote, shared database using the same JDBC settings. In such an instance, configuring a shared cache store prevents the unnecessary repeated write operations that occur when various cache instances attempt to write the same data to the cache store.
17.3.1. Invalidation Mode and Shared Cache Stores
When used in conjunction with a shared cache store, Red Hat JBoss Data Grid's invalidation mode causes remote caches to see the shared cache store to retrieve modified data.
The benefits of using invalidation mode in conjunction with shared cache stores include the following:
- Compared to replication messages, which contain the updated data, invalidation messages are much smaller and result in reduced network traffic.
- The remaining cluster caches look up modified data from the shared cache store lazily and only when required to do so, resulting in further reduced network traffic.
17.3.2. The Cache Store and Cache Passivation
In Red Hat JBoss Data Grid, a cache store can be used to enforce the passivation of entries and to activate eviction in a cache. Whether passivation mode or activation mode are used, the configured cache store both reads from and writes to the data store.
When passivation is disabled in JBoss Data Grid, after the modification, addition or removal of an element is carried out the cache store steps in to persist the changes in the store.
17.3.3. Application Cachestore Registration
It is not necessary to register an application cache store for an isolated deployment. This is not a requirement in Red Hat JBoss Data Grid because lazy deserialization is used to work around this problem.