Home > Storage > PowerScale (Isilon) > Product Documentation > Storage (general) > PowerScale OneFS Best Practices > OneFS storage efficiency
A typical dataset consists of a mix of large and small files stored in a file system consisting of a hierarchical directory structure. Usually, around 30 percent of the data is active; 70 percent is inactive. Snapshots typically back up the data for short-term retention combined with a long-term DR strategy, which frequently includes replication to a secondary cluster, and disk-to-disk or disk to tape NDMP backups.
In this document, large files are considered as files that are 128 KB or larger, and small files are files less than 128 KB. This is significant because at 128 KB and above, OneFS uses erasure coding (FEC) to parity protect a file, which results in high levels of storage efficiency. Conversely, files less than 128 KB in size are essentially mirrored, so have a larger on-disk footprint. Large file efficiency using erasure coding offsets the penalty of mirroring of small files.
OneFS also provides additional storage efficiency using its native, post-process deduplication engine, SmartDedupe, as well as in-line compression and deduplication. More details are provided in OneFS data reduction best practices.