Introducing ZFS Properties
Properties are the main mechanism that you use to control the behavior of file systems, volumes, snapshots, and clones. Unless stated otherwise, the properties defined in this section apply to all the dataset types.
Properties are divided into two types, native properties and user-defined properties. Native properties either provide internal statistics or control ZFS file system behavior. In addition, native properties are either settable or read-only. User properties have no effect on ZFS file system behavior, but you can use them to annotate datasets in a way that is meaningful in your environment. For more information about user properties, see ZFS User Properties.
Most settable properties are also inheritable. An inheritable property is a property that, when set on a parent file system, is propagated down to all of its descendents.
All inheritable properties have an associated source that indicates how a property was obtained. The source of a property can have the following values:
-
local
-
Indicates that the property was explicitly set on the dataset by using the
zfs set
command as described in Setting ZFS Properties. -
inherited from
dataset-name -
Indicates that the property was inherited from the named ancestor.
-
default
-
Indicates that the property value was not inherited or set locally. This source is a result of no ancestor having the property set as source
local
.
The following table identifies both read-only and settable native ZFS file system properties. Read-only native properties are identified as such. All other native properties listed in this table are settable. For information about user properties, see ZFS User Properties.
Table 7-1 ZFS Native Property Descriptions
Property Name | Type | Default Value | Description |
---|---|---|---|
|
String |
|
Controls how ACL entries are inherited when files and directories are created. The
values are |
|
String |
|
Controls how an ACL entry is modified during a |
|
Boolean |
|
Controls whether the access time for files is updated when they are read. Turning this property off avoids producing write traffic when reading files and can result in significant performance gains, though it might confuse mailers and similar utilities. |
|
Number |
N/A |
Read-only property that identifies the amount of disk space available to a file system and all its children, assuming no other activity in the pool. Because disk space is shared within a pool, available space can be limited by various factors including physical pool size, quotas, reservations, and other datasets within the pool. The property abbreviation is |
|
Boolean |
|
Controls whether a file system can be mounted with the When the For more information, see The canmount Property. |
|
String |
|
This property indicates whether the file name matching algorithm used by the file system should be The Regardless of the |
|
String |
|
Controls the checksum used to verify data integrity. The default value is |
|
String |
|
Enables or disables compression for a dataset. The values are The property abbreviation is |
|
Number |
N/A |
Read-only property that identifies the compression ratio achieved for a dataset, expressed as a multiplier. Compression can be enabled by the The value is calculated from the logical size of all files and the amount of referenced physical data. It includes explicit savings through the use of the |
|
Number |
|
Sets the number of copies of user data per file system. Available values are |
|
String |
N/A |
Read-only property that identifies the date and time that a dataset was created. |
|
String |
|
Controls the ability to remove duplicate data in a ZFS file system. Possible values are For more information, see The dedup Property. |
|
String |
None |
Sets a default group quota. The value applies to all groups who do not have an explicit group quota specified. The default value is none. For more information, see Setting Default User and Group Quotas. |
|
String |
None |
Sets a default user quota. The value applies to all users who do not have an explicit user quota specified. The default value is none. For more information, see Setting Default User and Group Quotas. |
|
Boolean |
|
Controls whether device files in a file system can be opened. |
|
Boolean |
|
Controls whether a file system is encrypted. An encrypted file system means that data is encoded and a key is needed by the file system owner to access the data. |
|
Boolean |
|
Controls whether programs in a file system are allowed to be executed. Also, when set to |
|
String |
none |
Read-only property that identifies the date of the last wrapping key change from a |
|
String |
none |
Identifies the format and location of the key that wraps the file system keys. The valid property values are |
|
String |
none |
Read-only property that identifies the file system's encryption key status. The availability of a file system's key is indicated by |
|
String |
|
Controls how ZFS optimizes synchronous requests for this file system. If |
|
String |
None |
Provides a sensitivity label that determines if a file system can be mounted in a zone. If the labeled file system matches the labeled zone, the file system can be mounted and accessed from the labeled zone. The default value is The behavior of the |
|
Boolean |
N/A |
Read-only property that indicates whether a file system, clone, or snapshot is currently mounted. This property does not apply to volumes. The value can be either |
|
String |
N/A |
Controls the mount point used for this file system. When the For more information about using this property, see Managing ZFS Mount Points. |
|
Boolean |
|
The A root file system, an Oracle Solaris Zone file system, or a file system that contains packaged Oracle Solaris code should not be multilevel. See The mlslabel Property for more information. |
|
Boolean |
|
Controls whether the file system should be mounted with |
|
String |
None |
This property indicates whether a file system should perform a unicode normalization of file names whenever two file names are compared, and which normalization algorithm should be used. File names are always stored unmodified, names are normalized as part of any comparison process. If this property is set to a legal value other than |
|
String |
N/A |
Read-only property for cloned file systems or volumes that identifies the snapshot from which the clone was created. The origin cannot be destroyed (even with the Non-cloned file systems have an origin of |
|
String |
|
Controls what is cached in the primary cache (ARC). Possible values are |
|
Number (or |
|
Limits the amount of disk space a file system and its descendents can consume. This property enforces a hard limit on the amount of disk space used, including all space consumed by descendents, such as file systems and snapshots. Setting a quota on a descendent of a file system that already has a quota does not override the ancestor's quota, but rather imposes an additional limit. Quotas cannot be set on volumes, as the For information about setting quotas, see Setting Quotas on ZFS File Systems. |
|
Boolean |
|
Controls whether a dataset can be modified. When set to The property abbreviation is |
|
Number |
|
Specifies a suggested block size for files in a file system. The property abbreviation is |
|
Number |
N/A |
Read-only property that identifies the amount of data accessible by a dataset, which might or might not be shared with other datasets in the pool. When a snapshot or clone is created, it initially references the same amount of disk space as the file system or snapshot it was created from, because its contents are identical. The property abbreviation is |
|
Number (or none) |
|
Sets the amount of disk space that a dataset can consume. This property enforces a hard limit on the amount of space used. This hard limit does not include disk space used by descendents, such as snapshots and clones. |
|
Number (or none) |
|
Sets the minimum amount of disk space that is guaranteed to a dataset, not including descendents, such as snapshots and clones. When the amount of disk space used is below this value, the dataset is treated as if it were taking up the amount of space specified by If The property abbreviation is |
|
String |
N/A |
Read-only property that indicates the date of the last data encryption key change from a |
|
Number (or none) |
|
Sets the minimum amount of disk space guaranteed to a file system and its descendents. When the amount of disk space used is below this value, the file system is treated as if it were using the amount of space specified by its reservation. Reservations are accounted for in the parent file system's disk space used, and count against the parent file system's quotas and reservations. The property abbreviation is For more information, see Setting Reservations on ZFS File Systems. |
|
Boolean |
on |
Indicates whether the file system owner can grant file ownership changes. The default is to restrict |
|
String |
|
Controls what is cached in the secondary cache (L2ARC). Possible values are |
|
Boolean |
|
Controls whether the |
|
String |
|
Identifies a ZFS file system as a shadow of the file system described by the URI. Data is migrated to a shadow file system with this property set from the file system identified by the URI. The file system to be migrated must be read-only for a complete migration. |
|
String |
|
Controls whether an NFS share of a ZFS file system is created and published and what options are used. You can also publish and unpublish an NFS share by using the For more information about sharing ZFS file systems, see Sharing and Unsharing ZFS File Systems. |
|
String |
|
Controls whether a SMB share of a ZFS file system is created and published and what options are used. You can also publish and unpublish an SMB share by using the |
|
String |
|
Controls whether the |
|
String |
|
Determines the synchronous behavior of a file system's transactions. Possible values are:
|
|
String |
N/A |
Read-only property that identifies the dataset type as |
|
Number |
N/A |
Read-only property that identifies the amount of disk space consumed by a dataset and all its descendents. For a detailed description, see ZFS Read-Only Native Properties. |
|
Number |
|
Read-only property that identifies the amount of disk space that is used by children of this dataset, which would be freed if all the dataset's children were destroyed. The property abbreviation is |
|
Number |
|
Read-only property that identifies the amount of disk space that is used by a dataset itself, which would be freed if the dataset was destroyed, after first destroying any snapshots and removing any |
|
Number |
|
Read-only property that identifies the amount of disk space that is used by a |
|
Number |
|
Read-only property that identifies the amount of disk space that is consumed by snapshots of a dataset. In particular, it is the amount of disk space that would be freed if all of this dataset's snapshots were destroyed. Note that this value is not simply the sum of the snapshots' |
|
Boolean |
|
This property indicates whether a file system should reject file names that include characters that are not present in the UTF-8 character code set. If this property is explicitly set to |
|
Number |
N/A |
Identifies the on-disk version of a file system, which is independent of the pool version. This property can only be set to a later version that is available from the supported software release. For more information, see the |
|
Number |
|
For volumes, specifies the block size of the volume. The block size cannot be changed after the volume has been written, so set the block size at volume creation time. The default block size for volumes is 8 KB. Any power of 2 from 512 bytes to 128 KB is valid. The property abbreviation is |
|
Number |
N/A |
For volumes, specifies the logical size of the volume. For a detailed description, see The volsize Property. |
|
Boolean |
|
Controls whether regular files should be scanned for viruses when a file is opened and closed. In addition to enabling this property, a virus scanning service must also be enabled for virus scanning to occur if you have third-party virus scanning software. The default value is |
|
Boolean |
|
Indicates whether extended attributes are enabled ( |
|
Boolean |
N/A |
Indicates whether a file system has been added to a non-global zone. If this property is set, then the mount point is not honored in the global zone, and ZFS cannot mount such a file system when requested. When a zone is first installed, this property is set for any added file systems. For more information about using ZFS with zones installed, see Using ZFS on an Oracle Solaris System With Zones Installed. |