Write caching with SmartCache

Write caching accelerates the process of writing data to the cluster. OneFS includes a write-caching feature called SmartChache, which is enabled by default for all files and directories.

If write caching is enabled, OneFS writes data to a write-back cache instead of immediately writing the data to disk. OneFS can write the data to disk at a time that is more convenient.

Note Image

We recommend that you keep write caching enabled. You should also enable write caching for all file pool policies.

OneFS interprets writes to the cluster as either synchronous or asynchronous, depending on a client's specifications. The impacts and risks of write caching depend on what protocols clients use to write to the cluster, and whether the writes are interpreted as synchronous or asynchronous. If you disable write caching, client specifications are ignored and all writes are performed synchronously.

The following table explains how clients' specifications are interpreted, according to the protocol.

Protocol
Synchronous
Asynchronous
NFS
The stable field is set to data_sync or file_sync.
The stable field is set to unstable.
SMB
The write-through flag has been applied.
The write-through flag has not been applied.