OneFS enables you to back up and restore file-system data through the Network Data Management Protocol (NDMP). From a backup server, you can direct backup and recovery processes between an Isilon cluster and backup devices such as tape devices, media servers, and virtual tape libraries (VTLs).
OneFS supports both NDMP three-way backup and NDMP two-way backup. During a three-way NDMP backup operation, a data management application (DMA) on a backup server instructs the cluster to start backing up data to a tape media server that is either attached to the LAN or directly attached to the DMA. During a two-way NDMP backup, a DMA on a backup server instructs a Backup Accelerator node on the cluster to start backing up data to a tape media server that is attached to the Backup Accelerator node. Two-way NDMP backup is the most efficient method in terms of cluster resource consumption; however, two-way NDMP backup requires that one or more Backup Accelerator nodes be attached to the cluster. In both the two-way and three-way NDMP backup models, file history data is transferred from the cluster to a backup server.
Before a backup begins, OneFS creates a snapshot of the targeted directory. OneFS then backs up the snapshot, which ensures that the backup image represents a specific point in time. After the backup is completed or canceled, OneFS automatically deletes the snapshot. You do not need to configure a SnapshotIQ license on the cluster to perform NDMP backups. However, if a SnapshotIQ license is configured on the cluster, you can generate a snapshot through the SnapshotIQ tool, and then back up the snapshot. If you back up a snapshot that you generated, OneFS does not create another snapshot for the backup.