OneFS protects data in the cluster based on the configured protection policy. OneFS rebuilds failed disks, uses free storage space across the entire cluster to further prevent data loss, monitors data, and migrates data off of at-risk components.
OneFS distributes all data and error-correction information across the cluster and ensures that all data remains intact and accessible even in the event of simultaneous component failures. Under normal operating conditions, all data on the cluster is protected against one or more failures of a node or drive. However, if a node or drive fails, the cluster protection status is considered to be in a degraded state until the data is protected by OneFS again. OneFS reprotects data by rebuilding data in the free space of the cluster. While the protection status is in a degraded state, data is more vulnerable to data loss.
Because data is rebuilt in the free space of the cluster, the cluster does not require a dedicated hot-spare node or drive in order to recover from a component failure. Because a certain amount of free space is required to rebuild data, it is recommended that you reserve adequate free space through the virtual hot spare feature.
As you add more nodes, the cluster gains more CPU, memory, and disks to use during recovery operations. As a cluster grows larger, data restriping operations become faster.