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zfs.8
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'\" t
.\"
.\" CDDL HEADER START
.\"
.\" The contents of this file are subject to the terms of the
.\" Common Development and Distribution License (the "License").
.\" You may not use this file except in compliance with the License.
.\"
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
.\" or http://www.opensolaris.org/os/licensing.
.\" See the License for the specific language governing permissions
.\" and limitations under the License.
.\"
.\" When distributing Covered Code, include this CDDL HEADER in each
.\" file and include the License file at usr/src/OPENSOLARIS.LICENSE.
.\" If applicable, add the following below this CDDL HEADER, with the
.\" fields enclosed by brackets "[]" replaced with your own identifying
.\" information: Portions Copyright [yyyy] [name of copyright owner]
.\"
.\" CDDL HEADER END
.\"
.\"
.\" Copyright (c) 2009 Sun Microsystems, Inc. All Rights Reserved.
.\" Copyright 2011 Joshua M. Clulow <josh@sysmgr.org>
.\" Copyright (c) 2014 by Delphix. All rights reserved.
.\" Copyright (c) 2014, Joyent, Inc. All rights reserved.
.\" Copyright 2012 Nexenta Systems, Inc. All Rights Reserved.
.\" Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
.\"
.TH zfs 8 "Nov 19, 2013" "ZFS pool 28, filesystem 5" "System Administration Commands"
.SH NAME
zfs \- configures ZFS file systems
.SH SYNOPSIS
.LP
.nf
\fBzfs\fR [\fB-?\fR]
.fi
.LP
.nf
\fBzfs\fR \fBcreate\fR [\fB-p\fR] [\fB-o\fR \fIproperty\fR=\fIvalue\fR] ... \fIfilesystem\fR
.fi
.LP
.nf
\fBzfs\fR \fBcreate\fR [\fB-ps\fR] [\fB-b\fR \fIblocksize\fR] [\fB-o\fR \fIproperty\fR=\fIvalue\fR] ... \fB-V\fR \fIsize\fR \fIvolume\fR
.fi
.LP
.nf
\fBzfs\fR \fBdestroy\fR [\fB-fnpRrv\fR] \fIfilesystem\fR|\fIvolume\fR
.fi
.LP
.nf
\fBzfs\fR \fBdestroy\fR [\fB-dnpRrv\fR] \fIfilesystem\fR|\fIvolume\fR@\fIsnap\fR[%\fIsnap\fR][,...]
.fi
.LP
.nf
\fBzfs\fR \fBdestroy\fR \fIfilesystem\fR|\fIvolume\fR#\fIbookmark\fR
.fi
.LP
.nf
\fBzfs\fR \fBsnapshot | snap\fR [\fB-r\fR] [\fB-o\fR \fIproperty\fR=\fIvalue\fR] ...
\fIfilesystem@snapname\fR|\fIvolume@snapname\fR ...
.fi
.LP
.nf
\fBzfs\fR \fBrollback\fR [\fB-rRf\fR] \fIsnapshot\fR
.fi
.LP
.nf
\fBzfs\fR \fBclone\fR [\fB-p\fR] [\fB-o\fR \fIproperty\fR=\fIvalue\fR] ... \fIsnapshot\fR \fIfilesystem\fR|\fIvolume\fR
.fi
.LP
.nf
\fBzfs\fR \fBpromote\fR \fIclone-filesystem\fR
.fi
.LP
.nf
\fBzfs\fR \fBrename\fR [\fB-f\fR] \fIfilesystem\fR|\fIvolume\fR|\fIsnapshot\fR
\fIfilesystem\fR|\fIvolume\fR|\fIsnapshot\fR
.fi
.LP
.nf
\fBzfs\fR \fBrename\fR [\fB-fp\fR] \fIfilesystem\fR|\fIvolume\fR \fIfilesystem\fR|\fIvolume\fR
.fi
.LP
.nf
\fBzfs\fR \fBrename\fR \fB-r\fR \fIsnapshot\fR \fIsnapshot\fR
.fi
.LP
.nf
\fBzfs\fR \fBlist\fR [\fB-r\fR|\fB-d\fR \fIdepth\fR][\fB-Hp\fR][\fB-o\fR \fIproperty\fR[,\fIproperty\fR]...] [\fB-t\fR \fItype\fR[,\fItype\fR]..]
[\fB-s\fR \fIproperty\fR] ... [\fB-S\fR \fIproperty\fR] ... [\fIfilesystem\fR|\fIvolume\fR|\fIsnapshot\fR] ...
.fi
.LP
.nf
\fBzfs\fR \fBset\fR \fIproperty\fR=\fIvalue\fR \fIfilesystem\fR|\fIvolume\fR|\fIsnapshot\fR ...
.fi
.LP
.nf
\fBzfs\fR \fBget\fR [\fB-r\fR|\fB-d\fR \fIdepth\fR][\fB-Hp\fR][\fB-o\fR \fIfield\fR[,...]] [\fB-t\fR \fItype\fR[,...]]
[\fB-s\fR \fIsource\fR[,...]] "\fIall\fR" | \fIproperty\fR[,...] \fIfilesystem\fR|\fIvolume\fR|\fIsnapshot\fR ...
.fi
.LP
.nf
\fBzfs\fR \fBinherit\fR [\fB-rS\fR] \fIproperty\fR \fIfilesystem\fR|\fIvolume|snapshot\fR ...
.fi
.LP
.nf
\fBzfs\fR \fBupgrade\fR [\fB-v\fR]
.fi
.LP
.nf
\fBzfs\fR \fBupgrade\fR [\fB-r\fR] [\fB-V\fR \fIversion\fR] \fB-a\fR | \fIfilesystem\fR
.fi
.LP
.nf
\fBzfs\fR \fBuserspace\fR [\fB-Hinp\fR] [\fB-o\fR \fIfield\fR[,...]] [\fB-s\fR \fIfield\fR] ...
[\fB-S\fR \fIfield\fR] ... [\fB-t\fR \fItype\fR[,...]] \fIfilesystem\fR|\fIsnapshot\fR
.fi
.LP
.nf
\fBzfs\fR \fBgroupspace\fR [\fB-Hinp\fR] [\fB-o\fR \fIfield\fR[,...]] [\fB-s\fR \fIfield\fR] ...
[\fB-S\fR \fIfield\fR] ... [\fB-t\fR \fItype\fR[,...]] \fIfilesystem\fR|\fIsnapshot\fR
.fi
.LP
.nf
\fBzfs\fR \fBmount\fR
.fi
.LP
.nf
\fBzfs\fR \fBmount\fR [\fB-vO\fR] [\fB-o \fIoptions\fR\fR] \fB-a\fR | \fIfilesystem\fR
.fi
.LP
.nf
\fBzfs\fR \fBunmount | umount\fR [\fB-f\fR] \fB-a\fR | \fIfilesystem\fR|\fImountpoint\fR
.fi
.LP
.nf
\fBzfs\fR \fBshare\fR \fB-a\fR | \fIfilesystem\fR
.fi
.LP
.nf
\fBzfs\fR \fBunshare\fR \fB-a\fR \fIfilesystem\fR|\fImountpoint\fR
.fi
.LP
.nf
\fBzfs\fR \fBbookmark\fR \fIsnapshot\fR \fIbookmark\fR
.fi
.LP
.nf
\fBzfs\fR \fBsend\fR [\fB-DnPpRveL\fR] [\fB-\fR[\fBiI\fR] \fIsnapshot\fR] \fIsnapshot\fR
.fi
.LP
.nf
\fBzfs\fR \fBsend\fR [\fB-eL\fR] [\fB-i \fIsnapshot\fR|\fIbookmark\fR]\fR \fIfilesystem\fR|\fIvolume\fR|\fIsnapshot\fR
.fi
.LP
.nf
\fBzfs\fR \fBreceive | recv\fR [\fB-vnFu\fR] \fIfilesystem\fR|\fIvolume\fR|\fIsnapshot\fR
.fi
.LP
.nf
\fBzfs\fR \fBreceive | recv\fR [\fB-vnFu\fR] [\fB-d\fR|\fB-e\fR] \fIfilesystem\fR
.fi
.LP
.nf
\fBzfs\fR \fBallow\fR \fIfilesystem\fR|\fIvolume\fR
.fi
.LP
.nf
\fBzfs\fR \fBallow\fR [\fB-ldug\fR] "\fIeveryone\fR"|\fIuser\fR|\fIgroup\fR[,...] \fIperm\fR|\fI@setname\fR[,...]
\fIfilesystem\fR|\fIvolume\fR
.fi
.LP
.nf
\fBzfs\fR \fBallow\fR [\fB-ld\fR] \fB-e\fR \fIperm\fR|@\fIsetname\fR[,...] \fIfilesystem\fR|\fIvolume\fR
.fi
.LP
.nf
\fBzfs\fR \fBallow\fR \fB-c\fR \fIperm\fR|@\fIsetname\fR[,...] \fIfilesystem\fR|\fIvolume\fR
.fi
.LP
.nf
\fBzfs\fR \fBallow\fR \fB-s\fR @\fIsetname\fR \fIperm\fR|@\fIsetname\fR[,...] \fIfilesystem\fR|\fIvolume\fR
.fi
.LP
.nf
\fBzfs\fR \fBunallow\fR [\fB-rldug\fR] "\fIeveryone\fR"|\fIuser\fR|\fIgroup\fR[,...] [\fIperm\fR|@\fIsetname\fR[,... ]]
\fIfilesystem\fR|\fIvolume\fR
.fi
.LP
.nf
\fBzfs\fR \fBunallow\fR [\fB-rld\fR] \fB-e\fR [\fIperm\fR|@\fIsetname\fR[,... ]] \fIfilesystem\fR|\fIvolume\fR
.fi
.LP
.nf
\fBzfs\fR \fBunallow\fR [\fB-r\fR] \fB-c\fR [\fIperm\fR|@\fIsetname\fR[ ... ]] \fIfilesystem\fR|\fIvolume\fR
.fi
.LP
.nf
\fBzfs\fR \fBunallow\fR [\fB-r\fR] \fB-s\fR @\fIsetname\fR [\fIperm\fR|@\fIsetname\fR[,... ]] \fIfilesystem\fR|\fIvolume\fR
.fi
.LP
.nf
\fBzfs\fR \fBhold\fR [\fB-r\fR] \fItag\fR \fIsnapshot\fR...
.fi
.LP
.nf
\fBzfs\fR \fBholds\fR [\fB-r\fR] \fIsnapshot\fR...
.fi
.LP
.nf
\fBzfs\fR \fBrelease\fR [\fB-r\fR] \fItag\fR \fIsnapshot\fR...
.fi
.LP
.nf
\fBzfs\fR \fBdiff\fR [\fB-FHt\fR] \fIsnapshot\fR \fIsnapshot|filesystem\fR
.SH DESCRIPTION
.LP
The \fBzfs\fR command configures \fBZFS\fR datasets within a \fBZFS\fR storage pool, as described in \fBzpool\fR(8). A dataset is identified by a unique path within the \fBZFS\fR namespace. For example:
.sp
.in +2
.nf
pool/{filesystem,volume,snapshot}
.fi
.in -2
.sp
.sp
.LP
where the maximum length of a dataset name is \fBMAXNAMELEN\fR (256 bytes).
.sp
.LP
A dataset can be one of the following:
.sp
.ne 2
.mk
.na
\fB\fIfile system\fR\fR
.ad
.sp .6
.RS 4n
A \fBZFS\fR dataset of type \fBfilesystem\fR can be mounted within the standard system namespace and behaves like other file systems. While \fBZFS\fR file systems are designed to be \fBPOSIX\fR compliant, known issues exist that prevent compliance in some cases. Applications that depend on standards conformance might fail due to nonstandard behavior when checking file system free space.
.RE
.sp
.ne 2
.mk
.na
\fB\fIvolume\fR\fR
.ad
.sp .6
.RS 4n
A logical volume exported as a raw or block device. This type of dataset should only be used under special circumstances. File systems are typically used in most environments.
.RE
.sp
.ne 2
.mk
.na
\fB\fIsnapshot\fR\fR
.ad
.sp .6
.RS 4n
A read-only version of a file system or volume at a given point in time. It is specified as \fIfilesystem@name\fR or \fIvolume@name\fR.
.RE
.sp
.ne 2
.mk
.na
\fB\fIbookmark\fR\fR
.ad
.sp .6
.RS 4n
Much like a \fIsnapshot\fR, but without the hold on on-disk data. It can be used as the source of a send (but not for a receive).
It is specified as \fIfilesystem#name\fR or \fIvolume#name\fR.
.RE
.SS "ZFS File System Hierarchy"
.LP
A \fBZFS\fR storage pool is a logical collection of devices that provide space for datasets. A storage pool is also the root of the \fBZFS\fR file system hierarchy.
.sp
.LP
The root of the pool can be accessed as a file system, such as mounting and unmounting, taking snapshots, and setting properties. The physical storage characteristics, however, are managed by the \fBzpool\fR(8) command.
.sp
.LP
See \fBzpool\fR(8) for more information on creating and administering pools.
.SS "Snapshots"
.LP
A snapshot is a read-only copy of a file system or volume. Snapshots can be created extremely quickly, and initially consume no additional space within the pool. As data within the active dataset changes, the snapshot consumes more data than would otherwise be shared with the active dataset.
.sp
.LP
Snapshots can have arbitrary names. Snapshots of volumes can be cloned or rolled back. Visibility is determined by the \fBsnapdev\fR property of the parent volume.
.sp
.LP
File system snapshots can be accessed under the \fB\&.zfs/snapshot\fR directory in the root of the file system. Snapshots are automatically mounted on demand and may be unmounted at regular intervals. The visibility of the \fB\&.zfs\fR directory can be controlled by the \fBsnapdir\fR property.
.SS "Bookmarks"
.LP
A bookmark is like a snapshot, a read-only copy of a file system or volume. Bookmarks can be created extremely quickly, compared to snapshots, and they consume no additional space within the pool. Bookmarks can also have arbitrary names, much like snapshots.
.sp
.LP
Unlike snapshots, bookmarks can not be accessed through the filesystem in any way. From a storage standpoint a bookmark just provides a way to reference when a snapshot was created as a distinct object. Bookmarks are initially tied to a snapshot, not the filesystem/volume, and they will survive if the snapshot itself is destroyed. Since they are very light weight there's little incentive to destroy them.
.SS "Clones"
.LP
A clone is a writable volume or file system whose initial contents are the same as another dataset. As with snapshots, creating a clone is nearly instantaneous, and initially consumes no additional space.
.sp
.LP
Clones can only be created from a snapshot. When a snapshot is cloned, it creates an implicit dependency between the parent and child. Even though the clone is created somewhere else in the dataset hierarchy, the original snapshot cannot be destroyed as long as a clone exists. The \fBorigin\fR property exposes this dependency, and the \fBdestroy\fR command lists any such dependencies, if they exist.
.sp
.LP
The clone parent-child dependency relationship can be reversed by using the \fBpromote\fR subcommand. This causes the "origin" file system to become a clone of the specified file system, which makes it possible to destroy the file system that the clone was created from.
.SS "Mount Points"
.LP
Creating a \fBZFS\fR file system is a simple operation, so the number of file systems per system is likely to be numerous. To cope with this, \fBZFS\fR automatically manages mounting and unmounting file systems without the need to edit the \fB/etc/fstab\fR file. All automatically managed file systems are mounted by \fBZFS\fR at boot time.
.sp
.LP
By default, file systems are mounted under \fB/\fIpath\fR\fR, where \fIpath\fR is the name of the file system in the \fBZFS\fR namespace. Directories are created and destroyed as needed.
.sp
.LP
A file system can also have a mount point set in the \fBmountpoint\fR property. This directory is created as needed, and \fBZFS\fR automatically mounts the file system when the \fBzfs mount -a\fR command is invoked (without editing \fB/etc/fstab\fR). The \fBmountpoint\fR property can be inherited, so if \fBpool/home\fR has a mount point of \fB/export/stuff\fR, then \fBpool/home/user\fR automatically inherits a mount point of \fB/export/stuff/user\fR.
.sp
.LP
A file system \fBmountpoint\fR property of \fBnone\fR prevents the file system from being mounted.
.sp
.LP
If needed, \fBZFS\fR file systems can also be managed with traditional tools (\fBmount\fR, \fBumount\fR, \fB/etc/fstab\fR). If a file system's mount point is set to \fBlegacy\fR, \fBZFS\fR makes no attempt to manage the file system, and the administrator is responsible for mounting and unmounting the file system.
.SS "Deduplication"
.LP
Deduplication is the process for removing redundant data at the block-level, reducing the total amount of data stored. If a file system has the \fBdedup\fR property enabled, duplicate data blocks are removed synchronously. The result is that only unique data is stored and common components are shared among files.
.sp
\fBWARNING: DO NOT ENABLE DEDUPLICATION UNLESS YOU NEED IT AND KNOW EXACTLY WHAT YOU ARE DOING!\fR
.sp
Deduplicating data is a very resource-intensive operation. It is generally recommended that you have \fIat least\fR 1.25 GB of RAM per 1 TB of storage when you enable deduplication. But calculating the exact requirenments is a somewhat complicated affair. Please see the \fBOracle Dedup Guide\fR for more information..
.sp
Enabling deduplication on an improperly-designed system will result in extreme performance issues (extremely slow filesystem and snapshot deletions etc.) and can potentially lead to data loss (i.e. unimportable pool due to memory exhaustion) if your system is not built for this purpose. Deduplication affects the processing power (CPU), disks (and the controller) as well as primary (real) memory.
.sp
Before creating a pool with deduplication enabled, ensure that you have planned your hardware requirements appropriately and implemented appropriate recovery practices, such as regular backups.
.sp
Unless necessary, deduplication should NOT be enabled on a system. Instead, consider using \fIcompression=lz4\fR, as a less resource-intensive alternative.
.SS "Native Properties"
.LP
Properties are divided into two types, native properties and user-defined (or "user") properties. Native properties either export internal statistics or control \fBZFS\fR behavior. In addition, native properties are either editable or read-only. User properties have no effect on \fBZFS\fR 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 the "User Properties" section, below.
.sp
.LP
Every dataset has a set of properties that export statistics about the dataset as well as control various behaviors. Properties are inherited from the parent unless overridden by the child. Some properties apply only to certain types of datasets (file systems, volumes, or snapshots).
.sp
.LP
The values of numeric properties can be specified using human-readable suffixes (for example, \fBk\fR, \fBKB\fR, \fBM\fR, \fBGb\fR, and so forth, up to \fBZ\fR for zettabyte). The following are all valid (and equal) specifications:
.sp
.in +2
.nf
1536M, 1.5g, 1.50GB
.fi
.in -2
.sp
.sp
.LP
The values of non-numeric properties are case sensitive and must be lowercase, except for \fBmountpoint\fR, \fBsharenfs\fR, and \fBsharesmb\fR.
.sp
.LP
The following native properties consist of read-only statistics about the dataset. These properties can be neither set, nor inherited. Native properties apply to all dataset types unless otherwise noted.
.sp
.ne 2
.mk
.na
\fB\fBavailable\fR\fR
.ad
.sp .6
.RS 4n
The amount of space available to the dataset and all its children, assuming that there is no other activity in the pool. Because space is shared within a pool, availability can be limited by any number of factors, including physical pool size, quotas, reservations, or other datasets within the pool.
.sp
This property can also be referred to by its shortened column name, \fBavail\fR.
.RE
.sp
.ne 2
.mk
.na
\fB\fBcompressratio\fR\fR
.ad
.sp .6
.RS 4n
For non-snapshots, the compression ratio achieved for the \fBused\fR space of this dataset, expressed as a multiplier. The \fBused\fR property includes descendant datasets, and, for clones, does not include the space shared with the origin snapshot. For snapshots, the \fBcompressratio\fR is the same as the \fBrefcompressratio\fR property. Compression can be turned on by running: \fBzfs set compression=on \fIdataset\fR\fR. The default value is \fBoff\fR.
.RE
.sp
.ne 2
.mk
.na
\fB\fBcreation\fR\fR
.ad
.sp .6
.RS 4n
The time this dataset was created.
.RE
.sp
.ne 2
.mk
.na
\fB\fBclones\fR\fR
.ad
.sp .6
.RS 4n
For snapshots, this property is a comma-separated list of filesystems or
volumes which are clones of this snapshot. The clones' \fBorigin\fR property
is this snapshot. If the \fBclones\fR property is not empty, then this
snapshot can not be destroyed (even with the \fB-r\fR or \fB-f\fR options).
.RE
.sp
.ne 2
.na
\fB\fBdefer_destroy\fR\fR
.ad
.sp .6
.RS 4n
This property is \fBon\fR if the snapshot has been marked for deferred destruction by using the \fBzfs destroy\fR \fB-d\fR command. Otherwise, the property is \fBoff\fR.
.RE
.sp
.ne 2
.mk
.na
\fB\fBfilesystem_count\fR
.ad
.sp .6
.RS 4n
The total number of filesystems and volumes that exist under this location in the
dataset tree. This value is only available when a \fBfilesystem_limit\fR has
been set somewhere in the tree under which the dataset resides.
.RE
.sp
.ne 2
.na
\fB\fBlogicalreferenced\fR\fR
.ad
.sp .6
.RS 4n
The amount of space that is "logically" accessible by this dataset. See
the \fBreferenced\fR property. The logical space ignores the effect of
the \fBcompression\fR and \fBcopies\fR properties, giving a quantity
closer to the amount of data that applications see. However, it does
include space consumed by metadata.
.sp
This property can also be referred to by its shortened column name,
\fBlrefer\fR.
.RE
.sp
.ne 2
.na
\fB\fBlogicalused\fR\fR
.ad
.sp .6
.RS 4n
The amount of space that is "logically" consumed by this dataset and all
its descendents. See the \fBused\fR property. The logical space
ignores the effect of the \fBcompression\fR and \fBcopies\fR properties,
giving a quantity closer to the amount of data that applications see.
However, it does include space consumed by metadata.
.sp
This property can also be referred to by its shortened column name,
\fBlused\fR.
.RE
.sp
.ne 2
.na
\fB\fBmounted\fR\fR
.ad
.sp .6
.RS 4n
For file systems, indicates whether the file system is currently mounted. This property can be either \fByes\fR or \fBno\fR.
.RE
.sp
.ne 2
.mk
.na
\fB\fBorigin\fR\fR
.ad
.sp .6
.RS 4n
For cloned file systems or volumes, the snapshot from which the clone was created. See also the \fBclones\fR property.
.RE
.sp
.ne 2
.mk
.na
\fB\fBreferenced\fR\fR
.ad
.sp .6
.RS 4n
The amount of data that is accessible by this dataset, which may or may not be shared with other datasets in the pool. When a snapshot or clone is created, it initially references the same amount of space as the file system or snapshot it was created from, since its contents are identical.
.sp
This property can also be referred to by its shortened column name, \fBrefer\fR.
.RE
.sp
.ne 2
.mk
.na
\fB\fBrefcompressratio\fR\fR
.ad
.sp .6
.RS 4n
The compression ratio achieved for the \fBreferenced\fR space of this
dataset, expressed as a multiplier. See also the \fBcompressratio\fR
property.
.RE
.sp
.ne 2
.mk
.na
\fB\fBsnapshot_count\fR
.ad
.sp .6
.RS 4n
The total number of snapshots that exist under this location in the dataset tree.
This value is only available when a \fBsnapshot_limit\fR has been set somewhere
in the tree under which the dataset resides.
.RE
.sp
.ne 2
.na
\fB\fBtype\fR\fR
.ad
.sp .6
.RS 4n
The type of dataset: \fBfilesystem\fR, \fBvolume\fR, or \fBsnapshot\fR.
.RE
.sp
.ne 2
.mk
.na
\fB\fBused\fR\fR
.ad
.sp .6
.RS 4n
The amount of space consumed by this dataset and all its descendents. This is the value that is checked against this dataset's quota and reservation. The space used does not include this dataset's reservation, but does take into account the reservations of any descendent datasets. The amount of space that a dataset consumes from its parent, as well as the amount of space that are freed if this dataset is recursively destroyed, is the greater of its space used and its reservation.
.sp
When snapshots (see the "Snapshots" section) are created, their space is initially shared between the snapshot and the file system, and possibly with previous snapshots. As the file system changes, space that was previously shared becomes unique to the snapshot, and counted in the snapshot's space used. Additionally, deleting snapshots can increase the amount of space unique to (and used by) other snapshots.
.sp
The amount of space used, available, or referenced does not take into account pending changes. Pending changes are generally accounted for within a few seconds. Committing a change to a disk using \fBfsync\fR(2) or \fBO_SYNC\fR does not necessarily guarantee that the space usage information is updated immediately.
.RE
.sp
.ne 2
.mk
.na
\fB\fBusedby*\fR\fR
.ad
.sp .6
.RS 4n
The \fBusedby*\fR properties decompose the \fBused\fR properties into the various reasons that space is used. Specifically, \fBused\fR = \fBusedbychildren\fR + \fBusedbydataset\fR + \fBusedbyrefreservation\fR +, \fBusedbysnapshots\fR. These properties are only available for datasets created on \fBzpool\fR "version 13" pools.
.RE
.sp
.ne 2
.mk
.na
\fB\fBusedbychildren\fR\fR
.ad
.sp .6
.RS 4n
The amount of space used by children of this dataset, which would be freed if all the dataset's children were destroyed.
.RE
.sp
.ne 2
.mk
.na
\fB\fBusedbydataset\fR\fR
.ad
.sp .6
.RS 4n
The amount of space used by this dataset itself, which would be freed if the dataset were destroyed (after first removing any \fBrefreservation\fR and destroying any necessary snapshots or descendents).
.RE
.sp
.ne 2
.mk
.na
\fB\fBusedbyrefreservation\fR\fR
.ad
.sp .6
.RS 4n
The amount of space used by a \fBrefreservation\fR set on this dataset, which would be freed if the \fBrefreservation\fR was removed.
.RE
.sp
.ne 2
.mk
.na
\fB\fBusedbysnapshots\fR\fR
.ad
.sp .6
.RS 4n
The amount of space consumed by snapshots of this dataset. In particular, it is the amount of space that would be freed if all of this dataset's snapshots were destroyed. Note that this is not simply the sum of the snapshots' \fBused\fR properties because space can be shared by multiple snapshots.
.RE
.sp
.ne 2
.mk
.na
\fB\fBuserused@\fR\fIuser\fR\fR
.ad
.sp .6
.RS 4n
The amount of space consumed by the specified user in this dataset. Space is charged to the owner of each file, as displayed by \fBls\fR \fB-l\fR. The amount of space charged is displayed by \fBdu\fR and \fBls\fR \fB-s\fR. See the \fBzfs userspace\fR subcommand for more information.
.sp
Unprivileged users can access only their own space usage. The root user, or a user who has been granted the \fBuserused\fR privilege with \fBzfs allow\fR, can access everyone's usage.
.sp
The \fBuserused@\fR... properties are not displayed by \fBzfs get all\fR. The user's name must be appended after the \fB@\fR symbol, using one of the following forms:
.RS +4
.TP
.ie t \(bu
.el o
\fIPOSIX name\fR (for example, \fBjoe\fR)
.RE
.RS +4
.TP
.ie t \(bu
.el o
\fIPOSIX numeric ID\fR (for example, \fB789\fR)
.RE
.RS +4
.TP
.ie t \(bu
.el o
\fISID name\fR (for example, \fBjoe.smith@mydomain\fR)
.RE
.RS +4
.TP
.ie t \(bu
.el o
\fISID numeric ID\fR (for example, \fBS-1-123-456-789\fR)
.RE
.RE
.sp
.ne 2
.mk
.na
\fB\fBuserrefs\fR\fR
.ad
.sp .6
.RS 4n
This property is set to the number of user holds on this snapshot. User holds are set by using the \fBzfs hold\fR command.
.RE
.sp
.ne 2
.mk
.na
\fB\fBgroupused@\fR\fIgroup\fR\fR
.ad
.sp .6
.RS 4n
The amount of space consumed by the specified group in this dataset. Space is charged to the group of each file, as displayed by \fBls\fR \fB-l\fR. See the \fBuserused@\fR\fIuser\fR property for more information.
.sp
Unprivileged users can only access their own groups' space usage. The root user, or a user who has been granted the \fBgroupused\fR privilege with \fBzfs allow\fR, can access all groups' usage.
.RE
.sp
.ne 2
.mk
.na
\fB\fBvolblocksize\fR=\fIblocksize\fR\fR
.ad
.sp .6
.RS 4n
For volumes, specifies the block size of the volume. The \fBblocksize\fR cannot be changed once the volume has been written, so it should be set at volume creation time. The default \fBblocksize\fR for volumes is 8 Kbytes. Any power of 2 from 512 bytes to 128 Kbytes is valid.
.sp
This property can also be referred to by its shortened column name, \fBvolblock\fR.
.RE
.sp
.ne 2
.na
\fB\fBwritten\fR\fR
.ad
.sp .6
.RS 4n
The amount of \fBreferenced\fR space written to this dataset since the
previous snapshot.
.RE
.sp
.ne 2
.na
\fB\fBwritten@\fR\fIsnapshot\fR\fR
.ad
.sp .6
.RS 4n
The amount of \fBreferenced\fR space written to this dataset since the
specified snapshot. This is the space that is referenced by this dataset
but was not referenced by the specified snapshot.
.sp
The \fIsnapshot\fR may be specified as a short snapshot name (just the part
after the \fB@\fR), in which case it will be interpreted as a snapshot in
the same filesystem as this dataset.
The \fIsnapshot\fR be a full snapshot name (\fIfilesystem\fR@\fIsnapshot\fR),
which for clones may be a snapshot in the origin's filesystem (or the origin
of the origin's filesystem, etc).
.RE
.sp
.LP
The following native properties can be used to change the behavior of a \fBZFS\fR dataset.
.sp
.ne 2
.mk
.na
\fB\fBaclinherit\fR=\fBdiscard\fR | \fBnoallow\fR | \fBrestricted\fR | \fBpassthrough\fR | \fBpassthrough-x\fR\fR
.ad
.sp .6
.RS 4n
Controls how \fBACL\fR entries are inherited when files and directories are created. A file system with an \fBaclinherit\fR property of \fBdiscard\fR does not inherit any \fBACL\fR entries. A file system with an \fBaclinherit\fR property value of \fBnoallow\fR only inherits inheritable \fBACL\fR entries that specify "deny" permissions. The property value \fBrestricted\fR (the default) removes the \fBwrite_acl\fR and \fBwrite_owner\fR permissions when the \fBACL\fR entry is inherited. A file system with an \fBaclinherit\fR property value of \fBpassthrough\fR inherits all inheritable \fBACL\fR entries without any modifications made to the \fBACL\fR entries when they are inherited. A file system with an \fBaclinherit\fR property value of \fBpassthrough-x\fR has the same meaning as \fBpassthrough\fR, except that the \fBowner@\fR, \fBgroup@\fR, and \fBeveryone@\fR \fBACE\fRs inherit the execute permission only if the file creation mode also requests the execute bit.
.sp
When the property value is set to \fBpassthrough\fR, files are created with a mode determined by the inheritable \fBACE\fRs. If no inheritable \fBACE\fRs exist that affect the mode, then the mode is set in accordance to the requested mode from the application.
.sp
The \fBaclinherit\fR property does not apply to Posix ACLs.
.RE
.sp
.ne 2
.mk
.na
\fB\fBacltype\fR=\fBnoacl\fR | \fBposixacl\fR \fR
.ad
.sp .6
.RS 4n
Controls whether ACLs are enabled and if so what type of ACL to use. When
a file system has the \fBacltype\fR property set to \fBnoacl\fR (the default)
then ACLs are disabled. Setting the \fBacltype\fR property to \fBposixacl\fR
indicates Posix ACLs should be used. Posix ACLs are specific to Linux and
are not functional on other platforms. Posix ACLs are stored as an xattr and
therefore will not overwrite any existing ZFS/NFSv4 ACLs which may be set.
Currently only \fBposixacls\fR are supported on Linux.
.sp
To obtain the best performance when setting \fBposixacl\fR users are strongly
encouraged to set the \fBxattr=sa\fR property. This will result in the
Posix ACL being stored more efficiently on disk. But as a consequence of this
all new xattrs will only be accessible from ZFS implementations which support
the \fBxattr=sa\fR property. See the \fBxattr\fR property for more details.
.RE
.sp
.ne 2
.mk
.na
\fB\fBatime\fR=\fBon\fR | \fBoff\fR\fR
.ad
.sp .6
.RS 4n
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 other similar utilities. The default value is \fBon\fR. See also \fBrelatime\fR below.
.RE
.sp
.ne 2
.mk
.na
\fB\fBcanmount\fR=\fBon\fR | \fBoff\fR | \fBnoauto\fR\fR
.ad
.sp .6
.RS 4n
If this property is set to \fBoff\fR, the file system cannot be mounted, and is ignored by \fBzfs mount -a\fR. Setting this property to \fBoff\fR is similar to setting the \fBmountpoint\fR property to \fBnone\fR, except that the dataset still has a normal \fBmountpoint\fR property, which can be inherited. Setting this property to \fBoff\fR allows datasets to be used solely as a mechanism to inherit properties. One example of setting \fBcanmount=\fR\fBoff\fR is to have two datasets with the same \fBmountpoint\fR, so that the children of both datasets appear in the same directory, but might have different inherited characteristics.
.sp
When the \fBnoauto\fR option is set, a dataset can only be mounted and unmounted explicitly. The dataset is not mounted automatically when the dataset is created or imported, nor is it mounted by the \fBzfs mount -a\fR command or unmounted by the \fBzfs unmount -a\fR command.
.sp
This property is not inherited.
.RE
.sp
.ne 2
.mk
.na
\fB\fBchecksum\fR=\fBon\fR | \fBoff\fR | \fBfletcher2,\fR| \fBfletcher4\fR | \fBsha256\fR\fR
.ad
.sp .6
.RS 4n
Controls the checksum used to verify data integrity. The default value is \fBon\fR, which automatically selects an appropriate algorithm (currently, \fBfletcher4\fR, but this may change in future releases). The value \fBoff\fR disables integrity checking on user data. Disabling checksums is \fBNOT\fR a recommended practice.
.sp
Changing this property affects only newly-written data.
.RE
.sp
.ne 2
.mk
.na
\fB\fBcompression\fR=\fBon\fR | \fBoff\fR | \fBlzjb\fR | \fBlz4\fR |
\fBgzip\fR | \fBgzip-\fR\fIN\fR | \fBzle\fR\fR
.ad
.sp .6
.RS 4n
Controls the compression algorithm used for this dataset.
.sp
Setting compression to \fBon\fR indicates that the current default
compression algorithm should be used. The default balances compression
and decompression speed, with compression ratio and is expected to
work well on a wide variety of workloads. Unlike all other settings for
this property, \fBon\fR does not select a fixed compression type. As
new compression algorithms are added to ZFS and enabled on a pool, the
default compression algorithm may change. The current default compression
algorthm is either \fBlzjb\fR or, if the \fBlz4_compress\fR feature is
enabled, \fBlz4\fR.
.sp
The \fBlzjb\fR compression algorithm is optimized for performance while
providing decent data compression.
.sp
The \fBlz4\fR compression algorithm is a high-performance replacement
for the \fBlzjb\fR algorithm. It features significantly faster
compression and decompression, as well as a moderately higher
compression ratio than \fBlzjb\fR, but can only be used on pools with
the \fBlz4_compress\fR feature set to \fIenabled\fR. See
\fBzpool-features\fR(5) for details on ZFS feature flags and the
\fBlz4_compress\fR feature.
.sp
The \fBgzip\fR compression algorithm uses the same compression as
the \fBgzip\fR(1) command. You can specify the \fBgzip\fR level by using the
value \fBgzip-\fR\fIN\fR where \fIN\fR is an integer from 1 (fastest) to 9
(best compression ratio). Currently, \fBgzip\fR is equivalent to \fBgzip-6\fR
(which is also the default for \fBgzip\fR(1)). The \fBzle\fR compression
algorithm compresses runs of zeros.
.sp
This property can also be referred to by its shortened column name
\fBcompress\fR. Changing this property affects only newly-written data.
.RE
.sp
.ne 2
.mk
.na
\fB\fBcopies\fR=\fB1\fR | \fB2\fR | \fB3\fR\fR
.ad
.sp .6
.RS 4n
Controls the number of copies of data stored for this dataset. These copies are in addition to any redundancy provided by the pool, for example, mirroring or RAID-Z. The copies are stored on different disks, if possible. The space used by multiple copies is charged to the associated file and dataset, changing the \fBused\fR property and counting against quotas and reservations.
.sp
Changing this property only affects newly-written data. Therefore, set this property at file system creation time by using the \fB-o\fR \fBcopies=\fR\fIN\fR option.
.RE
.sp
.ne 2
.mk
.na
\fB\fBdedup\fR=\fBon\fR | \fBoff\fR | \fBverify\fR | \fBsha256\fR[,\fBverify\fR]\fR
.ad
.sp .6
.RS 4n
Controls whether deduplication is in effect for a dataset. The default value is \fBoff\fR. The default checksum used for deduplication is \fBsha256\fR (subject to change). When \fBdedup\fR is enabled, the \fBdedup\fR checksum algorithm overrides the \fBchecksum\fR property. Setting the value to \fBverify\fR is equivalent to specifying \fBsha256,verify\fR.
.sp
If the property is set to \fBverify\fR, then, whenever two blocks have the same signature, ZFS will do a byte-for-byte comparison with the existing block to ensure that the contents are identical.
.sp
Unless necessary, deduplication should NOT be enabled on a system. See \fBDeduplication\fR above.
.RE
.sp
.ne 2
.mk
.na
\fB\fBdevices\fR=\fBon\fR | \fBoff\fR\fR
.ad
.sp .6
.RS 4n
Controls whether device nodes can be opened on this file system. The default value is \fBon\fR.
.RE
.sp
.ne 2
.mk
.na
\fB\fBexec\fR=\fBon\fR | \fBoff\fR\fR
.ad
.sp .6
.RS 4n
Controls whether processes can be executed from within this file system. The default value is \fBon\fR.
.RE
.sp
.ne 2
.mk
.na
\fB\fBmlslabel\fR=\fIlabel\fR | \fBnone\fR\fR
.ad
.sp .6
.RS 4n
The \fBmlslabel\fR property is a sensitivity label that determines if a dataset can be mounted in a zone on a system with Trusted Extensions enabled. If the labeled dataset matches the labeled zone, the dataset can be mounted and accessed from the labeled zone.
.sp
When the \fBmlslabel\fR property is not set, the default value is \fBnone\fR. Setting the \fBmlslabel\fR property to \fBnone\fR is equivalent to removing the property.
.sp
The \fBmlslabel\fR property can be modified only when Trusted Extensions is enabled and only with appropriate privilege. Rights to modify it cannot be delegated. When changing a label to a higher label or setting the initial dataset label, the \fB{PRIV_FILE_UPGRADE_SL}\fR privilege is required. When changing a label to a lower label or the default (\fBnone\fR), the \fB{PRIV_FILE_DOWNGRADE_SL}\fR privilege is required. Changing the dataset to labels other than the default can be done only when the dataset is not mounted. When a dataset with the default label is mounted into a labeled-zone, the mount operation automatically sets the \fBmlslabel\fR property to the label of that zone.
.sp
When Trusted Extensions is \fBnot\fR enabled, only datasets with the default label (\fBnone\fR) can be mounted.
.sp
Zones are a Solaris feature and are not relevant on Linux.
.RE
.sp
.ne 2
.mk
.na
\fB\fBfilesystem_limit\fR=\fIcount\fR | \fBnone\fR\fR
.ad
.sp .6
.RS 4n
Limits the number of filesystems and volumes that can exist under this point in
the dataset tree. The limit is not enforced if the user is allowed to change
the limit. Setting a filesystem_limit on a descendent of a filesystem that
already has a filesystem_limit does not override the ancestor's filesystem_limit,
but rather imposes an additional limit. This feature must be enabled to be used
(see \fBzpool-features\fR(5)).
.RE
.sp
.ne 2
.na
\fB\fBmountpoint\fR=\fIpath\fR | \fBnone\fR | \fBlegacy\fR\fR
.ad
.sp .6
.RS 4n
Controls the mount point used for this file system. See the "Mount Points" section for more information on how this property is used.
.sp
When the \fBmountpoint\fR property is changed for a file system, the file system and any children that inherit the mount point are unmounted. If the new value is \fBlegacy\fR, then they remain unmounted. Otherwise, they are automatically remounted in the new location if the property was previously \fBlegacy\fR or \fBnone\fR, or if they were mounted before the property was changed. In addition, any shared file systems are unshared and shared in the new location.
.RE
.sp
.ne 2
.mk
.na
\fB\fBnbmand\fR=\fBon\fR | \fBoff\fR\fR
.ad
.sp .6
.RS 4n
Controls whether the file system should be mounted with \fBnbmand\fR (Non Blocking mandatory locks). This is used for \fBCIFS\fR clients. Changes to this property only take effect when the file system is umounted and remounted. See \fBmount\fR(8) for more information on \fBnbmand\fR mounts.
.RE
.sp
.ne 2
.mk
.na
\fB\fBprimarycache\fR=\fBall\fR | \fBnone\fR | \fBmetadata\fR\fR
.ad
.sp .6
.RS 4n
Controls what is cached in the primary cache (ARC). If this property is set to \fBall\fR, then both user data and metadata is cached. If this property is set to \fBnone\fR, then neither user data nor metadata is cached. If this property is set to \fBmetadata\fR, then only metadata is cached. The default value is \fBall\fR.
.RE