vSAN implements mechanisms for indicating failures and rebuilding unavailable data for data protection. Failure States of vSAN ComponentsIn vSAN, components that have failed can be in absent or degraded state. According to the component state, vSAN uses different approaches for recovering virtual machine data. Object States That Indicate Problems in vSANExamine the compliance status and the operational state of a virtual machine object to determine how a failure in the cluster affects the virtual machine. Accessibility of Virtual Machines Upon a Failure in vSANIf a virtual machine uses vSAN storage, its storage accessibility might change according to the type of failure in the vSAN cluster. Storage Device is Failing in a vSAN ClustervSAN monitors the performance of each storage device and proactively isolates unhealthy devices. It detects gradual failure of a storage device and isolates the device before congestion builds up within the affected host and the entire vSAN cluster. Capacity Device Not Accessible in a vSAN ClusterWhen a magnetic disk or flash capacity device fails, vSAN evaluates the accessibility of the objects on the device and rebuilds them on another host if space is available and the Primary level of failures to tolerate is set to 1 or more. A Flash Caching Device Is Not Accessible in a vSAN ClusterWhen a flash caching device fails, vSAN evaluates the accessibility of the objects on the disk group that contains the cache device, and rebuilds them on another host if possible and the Primary level of failures to tolerate is set to 1 or more. A Host Is Not Responding in a vSAN Cluster If a host stops responding because of a failure or reboot of the host, vSAN waits for the host to recover before vSAN rebuilds the components on the host elsewhere in the cluster. Network Connectivity Is Lost in the vSAN Cluster When the connectivity between the hosts in the cluster is lost, vSAN determines the active partition and rebuilds the components from the isolated partition on the active partition if the connectivity is not restored. A Storage Controller Fails in a vSAN ClusterWhen a storage controller fails, vSAN evaluates the accessibility of the objects on the disk groups that are attached to the controller and rebuilds them on another host. Stretched Cluster Site Fails or Loses Network ConnectionA vSAN stretched cluster manages failures that occur due to the loss of a network connection between sites or the temporary loss of one site. Parent topic: Handling Failures in vSAN
