If the "Lazy write" box is checked, JFS will defer writing data back to disk to a background thread. See "File-system caches" for an explanation.

If lazy-write is enabled, you can fine-tune the JFS cache's behavior with the three settings below (all values are in seconds):

  1. The "Synch time" setting determines the interval at which the JFS-internal synchronization thread runs. This defaults to 64.

  2. The "Max age" setting determines the maximum amount of time that data may be held in the cache. This defaults to 256.

  3. The "Buffer idle" value determines the amount of time during which JFS will consider a change to be "recent". Changes newer than this value are not written unless the last write was older than "max age." This defaults to 8.