Cluster Server 8.0 Bundled Agents Reference Guide - Windows
- Introducing VCS bundled agents
- Storage agents
- Network agents
- FileShare agents
- Services and applications agents
- VCS infrastructure and support agents
- VCS hardware replication agent for NetApp
- Troubleshooting bundled agents
DiskReservation (DiskRes) agent
The DiskReservation agent monitors shared disks. The agent also prevents data corruption caused by network partitioning, a condition in which two cluster systems provide the same services simultaneously. This condition occurs due to network link failure and may cause data corruption. The agent ensures only one cluster system holds persistent reservation to shared disks.
During a typical network partition, one system (SystemA) has the DiskRes resource online and holds reservation to shared disks. Another system (SystemB) attempts to come online and reserve the shared disks. To avoid network partitioning, SystemB issues a bus reset and waits for the interval specified in the GracePeriod attribute to determine if SystemA is functioning. If SystemA is functioning, SystemA reacquires reservation to the shared disks. Otherwise, SystemB attempts to reserve the shared disks. The system that gains reservation to the disks is designated owner of the resource, and the resource is brought online on that system.
By default, a system is designated owner of the resource if it reserves 80 percent of the shared disks. You can modify the agent's configuration to change the ownership criteria.
Note:
This agent is not supported in an SFW environment.