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Another key Job Engine task is AutoBalance. This task enables OneFS to reallocate and rebalance, or restripe, data across the nodes in a cluster, making storage space utilization more uniform and efficient.
OneFS manages protection of file data directly, and when a drive or entire node failure occurs, it rebuilds data in a parallel fashion. OneFS does not require either dedicated hot spare drives, or serial drive rebuilds. Instead, it borrows from the available free space in the file system to recover from failures. This technique is called Virtual Hot Spare. This approach allows the cluster to be self-healing, without human intervention, and with the advantages of fast, parallel data reconstruction. The administrator can create a virtual hot spare reserve, which prevents users from consuming capacity that is reserved for the virtual hot spare.
The process of choosing a new layout is called restriping, and this mechanism is identical for repair, rebalance, and tiering. Data is moved to the background, and the file is always available - a process that is transparent to end users and applications.
Note: Further information is available in the OneFS Job Engine white paper.