ZFS User Properties

In addition to the standard native properties, ZFS supports arbitrary user properties. User properties have no effect on ZFS behavior, but you can use them to annotate datasets with information that is meaningful in your environment.

User property names must conform to the following characteristics:

• Contain a colon (':') character to distinguish them from native properties.

• Contain lowercase letters, numbers, and the following punctuation characters: ':', '+','.', '_'.

• Maximum user property name is 256 characters.

The expected convention is that the property name is divided into the following two components but this namespace is not enforced by ZFS:

module:property

When making programmatic use of user properties, use a reversed DNS domain name for the module component of property names to reduce the chance that two independently-developed packages will use the same property name for different purposes. Property names that begin with "com.sun." are reserved for use by Sun Microsystems.

The values of user properties have the following characteristics:

• Arbitrary strings that are always inherited and are never validated.

• Maximum user property value is 1024 characters.

For example:

# zfs set dept:users=finance userpool/user1
# zfs set dept:users=general userpool/user2
# zfs set dept:users=itops userpool/user3

All of the commands that operate on properties, such as zfs list, zfs get, zfs set, and so on, can be used to manipulate both native properties and user properties.

For example:

zfs get -r dept:users userpool
NAME            PROPERTY    VALUE           SOURCE
userpool        dept:users  all             local
userpool/user1  dept:users  finance         local
userpool/user2  dept:users  general         local
userpool/user3  dept:users  itops           local

To clear a user property, use the zfs inherit command. For example:

# zfs inherit -r dept:users userpool

If the property is not defined in any parent dataset, it is removed entirely.