elasticsearch-js/docs/reference/api/ClusterStatsClusterFileSystem.md

ClusterStatsClusterFileSystem [interface-ClusterStatsClusterFileSystem]

Name	Type	Description
available_in_bytes	long	Total number of bytes available to JVM in file stores across all selected nodes. Depending on operating system or process-level restrictions, this number may be less than nodes.fs.free_in_byes. This is the actual amount of free disk space the selected Elasticsearch nodes can use.
free_in_bytes	long	Total number of unallocated bytes in file stores across all selected nodes.
total_in_bytes	long	Total size, in bytes, of all file stores across all selected nodes.