Note: Documentation for Pivotal GemFire 7.0.x is now available at http://docs.gopivotal.com/gemfire/index.html. Please reference the docs.gopivotal.com site for the latest and most up-to-date documentation on GemFire 7.0.x. The vFabric GemFire 7.0 documentation site will no longer be updated.

Region Consistency

GemFire ensures that all copies of a region eventually reach a consistent state on all members and clients that host the region.

By default GemFire members perform consistency checks when they apply updates to a distributed region, in order to ensure that all copies of the region eventually become consistent on all GemFire members and client caches that host the region. Different types of region ensure consistency using different techniques. However, when consistency checking is enabled (the default) all entries in a region require additional overhead in order to store version and timestamp information.

Although a region must have the same consistency checking configuration on all GemFire members that host the region, you can optionally disable consistency checking in a client cache region while leaving consistency checking enabled for the region on GemFire members. This configuration may be necessary in certain cases where the client must view all updates to a given region, even when GemFire members discards an update in order to preserve region consistency.

See Consistency for Region Updates in the vFabric GemFire User's Guide for more information.

Native Client Overhead for Consistency Checks

In the native client regions, the overhead for performing consistency check is an additional 11 bytes per region entry. This overhead is slightly smaller than the overhead required to provide consistency checking on server-side region entries.

If you cannot support the additional overhead in your deployment, you can disable consistency checks by setting the region attribute concurrency-checks-enabled to "false" for each region hosted by your client.