Disk Space for NFS on ZFS explained (Doc ID 2223897.1)

Last updated on MARCH 12, 2021

Applies to:

Solaris Operating System
Oracle ZFS Storage
Information in this document applies to any platform.

Purpose

The commands "du" and "df" as well as "ls" all have output concerned with the amount of storage a file occupies. In combination with ZFS or the ZFS Storage Array as the underlying storage architecture, and particularly when NFS is involved, this output is often the source for confusion. This document describes the output of these commands and shows some simple examples to address this confusion.

Scope

This document addresses these questions:

How can I tell how much storage a file uses?
How does that change with compression or snapshots?
How can I tell how much space is still available in a filesystem?
If my filesystem is NFS living on a ZFS storage array (or a Solaris system running NFS on ZFS), are the numbers shown by NFS and ZFS consistent? How do I tell?

This document does not go into the details of ZFS space management or space calculations. Please see the list of referenced documents for more information on this topic.