OneFS does not rely on hardware-based RAID for data protection. The PowerScale system uses the Reed-Solomon algorithm for N+M protection with Forward Error Correction (FEC).
Protection is applied at the file level, enabling the cluster to recover data quickly and efficiently. Nodes, directories, and other metadata are protected at the same or a higher level as the data blocks they reference. Since all data, metadata, and FEC blocks are spread across multiple nodes, dedicated parity drives are not required. For more information about PowerScale data protection, see Dell PowerScale OneFS: A Technical Overview.
Although cluster sizes as small as three nodes are possible, for safety and security applications we recommend a minimum of nodes. Sizing calculations must include a minimum free space calculation for proper cluster sizing. The Dell Technologies Safety & Security Lab recommends a cluster size that enables a node to be removed while retaining a minimum of 10 percent free space in the remaining capacity. This cluster size ensures that node removal and node failures have minimal or no impact on video ingestion.
The PowerScale sizing tool provides an accurate calculation (https://powersizer.dell.com/ui/index.html). Other sizing tools from video management software (VMS) and camera vendors may also be used for sizing the necessary bandwidth and storage capacity.
All Dell Technologies Safety & Security Lab tests were conducted with the protection level +2d:1n. This protection level could vary depending on your cluster size and implementation. Consult with your certified system integrator or Dell representative to determine the best protection level.