AppFabric 1.1 Caching: At least three cache hosts must be present in the cluster for the High Availability feature to function correctly
This topic is intended to address a specific issue identified by a Best Practices Analyzer scan. You should apply the information in this topic only to computers that have had the AppFabric 1.1 Caching Best Practices Analyzer run against them and are experiencing the issue addressed by this topic. For more information about best practices and scans, see Best Practices Analyzer.
Operating System |
Windows Server 2008 R2 |
Product/Feature |
Microsoft AppFabric 1.1 for Windows Server Caching |
Severity |
Error |
Category |
Configuration |
Issue
The cache cluster has the High Availability feature enabled, but the cluster has less than three cache hosts. High Availability creates a secondary copy of all cached items on another server. If there are only two servers in the cache cluster, stopping either of the cache hosts reduces the number of running cache hosts to one. In this case, the cache cluster is unable to maintain the high availability requirements, and the cache will be unusable until at least two cache clusters are running again.
Impact
The entire cluster will go down if one of the cache hosts goes down. This results in poor resiliency and reliability and increases the risk of outages or data loss.
Resolution
Add additional cache hosts to the cluster so that at least three hosts are present. This allows a single cache host to go down without impacting the cache cluster functionality. Or, if you do not require high availability, remove this configuration setting from any named caches.
Additional references
High Availability (AppFabric 1.1 Caching)
2012-09-12