Requesting data protection

You can specify the protection of a file or directory by setting its requested protection. This flexibility enables you to protect distinct sets of data at higher than default levels.

Requested protection of data is calculated by OneFS and set automatically on storage pools within your cluster. The default setting is referred to as suggested protection, and provides the optimal balance between data protection and storage efficiency. For example, a suggested protection of N+2:1 means that two drives or one node can fail without causing any data loss.

For best results, we recommend that you accept at least the suggested protection for data on your cluster. You can always specify a higher protection level than suggested protection on critical files, directories, or node pools.

OneFS allows you to request protection that the cluster is currently incapable of matching. If you request an unmatchable protection, the cluster will continue trying to match the requested protection until a match is possible. For example, in a four-node cluster, you might request a mirror protection of 5x. In this example, OneFS would mirror the data at 4x until you added a fifth node to the cluster, at which point OneFS would reprotect the data at 5x.

If you set requested protection to a level below suggested protection, OneFS warns you of this condition.

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For 4U Isilon IQ X-Series and NL-Series nodes, and IQ 12000X/EX 12000 combination platforms, the minimum cluster size of three nodes requires a minimum protection of N+2:1.