9-5-1 實作1 zfs Raid1 陣列替換固障硬碟
9-6-1 man zfs ( Proxmox VE )
zfs(8) System Administration Commands zfs(8)
NAME
zfs - configures ZFS file systems
SYNOPSIS
zfs [-?]
zfs create [-p] [-o property=value] ... filesystem
zfs create [-ps] [-b blocksize] [-o property=value] ... -V size volume
zfs destroy [-fnpRrv] filesystem|volume
zfs destroy [-dnpRrv] filesystem|volume@snap[%snap][,...]
zfs destroy filesystem|volume#bookmark
zfs snapshot | snap [-r] [-o property=value] ...
filesystem@snapname|volume@snapname ...
zfs rollback [-rRf] snapshot
zfs clone [-p] [-o property=value] ... snapshot filesystem|volume
zfs promote clone-filesystem
zfs rename [-f] filesystem|volume|snapshot
filesystem|volume|snapshot
zfs rename [-fp] filesystem|volume filesystem|volume
zfs rename -r snapshot snapshot
zfs list [-r|-d depth][-Hp][-o property[,property]...] [-t type[,type]..]
[-s property] ... [-S property] ... [filesystem|volume|snapshot] ...
zfs set property=value filesystem|volume|snapshot ...
zfs get [-r|-d depth][-Hp][-o field[,...]] [-t type[,...]]
[-s source[,...]] "all" | property[,...] filesystem|volume|snapshot ...
zfs inherit [-rS] property filesystem|volume|snapshot ...
zfs upgrade [-v]
zfs upgrade [-r] [-V version] -a | filesystem
zfs userspace [-Hinp] [-o field[,...]] [-s field] ...
[-S field] ... [-t type[,...]] filesystem|snapshot
zfs groupspace [-Hinp] [-o field[,...]] [-s field] ...
[-S field] ... [-t type[,...]] filesystem|snapshot
zfs mount
zfs mount [-vO] [-o options] -a | filesystem
zfs unmount | umount [-f] -a | filesystem|mountpoint
zfs share -a | filesystem
zfs unshare -a filesystem|mountpoint
zfs bookmark snapshot bookmark
zfs send [-DnPpRveL] [-[iI] snapshot] snapshot
zfs send [-eL] [-i snapshot|bookmark] filesystem|volume|snapshot
zfs receive | recv [-vnFus] filesystem|volume|snapshot
zfs receive | recv [-vnFus] [-d|-e] filesystem
zfs allow filesystem|volume
zfs allow [-ldug] "everyone"|user|group[,...] perm|@setname[,...]
filesystem|volume
zfs allow [-ld] -e perm|@setname[,...] filesystem|volume
zfs allow -c perm|@setname[,...] filesystem|volume
zfs allow -s @setname perm|@setname[,...] filesystem|volume
zfs unallow [-rldug] "everyone"|user|group[,...] [perm|@setname[,... ]]
filesystem|volume
zfs unallow [-rld] -e [perm|@setname[,... ]] filesystem|volume
zfs unallow [-r] -c [perm|@setname[ ... ]] filesystem|volume
zfs unallow [-r] -s @setname [perm|@setname[,... ]] filesystem|volume
zfs hold [-r] tag snapshot...
zfs holds [-r] snapshot...
zfs release [-r] tag snapshot...
zfs diff [-FHt] snapshot snapshot|filesystem
DESCRIPTION
The zfs command configures ZFS datasets within a ZFS storage pool, as
described in zpool(8). A dataset is identified by a unique path within
the ZFS namespace. For example:
pool/{filesystem,volume,snapshot}
where the maximum length of a dataset name is MAXNAMELEN (256 bytes).
A dataset can be one of the following:
file system
A ZFS dataset of type filesystem can be mounted within the standard
system namespace and behaves like other file systems. While ZFS
file systems are designed to be POSIX 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.
volume
A logical volume exported as a raw or block device. This type of
dataset should only be used under special circumstances. File sys?? tems are typically used in most environments.
snapshot
A read-only version of a file system or volume at a given point in
time. It is specified as filesystem@name or volume@name.
bookmark
Much like a snapshot, 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 filesystem#name or volume#name.
ZFS File System Hierarchy
A ZFS storage pool is a logical collection of devices that provide
space for datasets. A storage pool is also the root of the ZFS file
system hierarchy.
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 zpool(8) command.
See zpool(8) for more information on creating and administering pools.
Snapshots
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.
Snapshots can have arbitrary names. Snapshots of volumes can be cloned
or rolled back. Visibility is determined by the snapdev property of
the parent volume.
File system snapshots can be accessed under the .zfs/snapshot 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
.zfs directory can be controlled by the snapdir property.
Bookmarks
A bookmark is like a snapshot, a read-only copy of a file system or
volume. Bookmarks can be created extremely quickly, compared to snap?? shots, and they consume no additional space within the pool. Bookmarks
can also have arbitrary names, much like snapshots.
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.
Clones
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.
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 origin property exposes this dependency, and the destroy command
lists any such dependencies, if they exist.
The clone parent-child dependency relationship can be reversed by using
the promote 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.
Mount Points
Creating a ZFS file system is a simple operation, so the number of file
systems per system is likely to be numerous. To cope with this, ZFS
automatically manages mounting and unmounting file systems without the
need to edit the /etc/fstab file. All automatically managed file sys?? tems are mounted by ZFS at boot time.
By default, file systems are mounted under /path, where path is the
name of the file system in the ZFS namespace. Directories are created
and destroyed as needed.
A file system can also have a mount point set in the mountpoint prop?? erty. This directory is created as needed, and ZFS automatically mounts
the file system when the zfs mount -a command is invoked (without edit?? ing /etc/fstab). The mountpoint property can be inherited, so if
pool/home has a mount point of /export/stuff, then pool/home/user auto?? matically inherits a mount point of /export/stuff/user.
A file system mountpoint property of none prevents the file system from
being mounted.
If needed, ZFS file systems can also be managed with traditional tools
(mount, umount, /etc/fstab). If a file system's mount point is set to
legacy, ZFS makes no attempt to manage the file system, and the admin?? istrator is responsible for mounting and unmounting the file system.
Deduplication
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 dedup property enabled, duplicate data blocks are removed syn?? chronously. The result is that only unique data is stored and common
components are shared among files.
WARNING: DO NOT ENABLE DEDUPLICATION UNLESS YOU NEED IT AND KNOW
EXACTLY WHAT YOU ARE DOING!
Deduplicating data is a very resource-intensive operation. It is gener?? ally recommended that you have at least 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 Oracle
Dedup Guide for more information..
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. unim?? portable 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.
Before creating a pool with deduplication enabled, ensure that you have
planned your hardware requirements appropriately and implemented appro?? priate recovery practices, such as regular backups.
Unless necessary, deduplication should NOT be enabled on a system.
Instead, consider using compression=lz4, as a less resource-intensive
alternative.
Native Properties
Properties are divided into two types, native properties and user-
defined (or "user") properties. Native properties either export inter?? nal statistics or control ZFS behavior. In addition, native properties
are either editable or read-only. User properties have no effect on ZFS
behavior, but you can use them to annotate datasets in a way that is
meaningful in your environment. For more information about user proper?? ties, see the "User Properties" section, below.
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 snap?? shots).
The values of numeric properties can be specified using human-readable
suffixes (for example, k, KB, M, Gb, and so forth, up to Z for
zettabyte). The following are all valid (and equal) specifications:
1536M, 1.5g, 1.50GB
The values of non-numeric properties are case sensitive and must be
lowercase, except for mountpoint, sharenfs, and sharesmb.
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.
available
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.
This property can also be referred to by its shortened column name,
avail.
compressratio
For non-snapshots, the compression ratio achieved for the used
space of this dataset, expressed as a multiplier. The used prop?? erty includes descendant datasets, and, for clones, does not
include the space shared with the origin snapshot. For snapshots,
the compressratio is the same as the refcompressratio property.
Compression can be turned on by running: zfs set compression=on
dataset. The default value is off.
creation
The time this dataset was created.
clones
For snapshots, this property is a comma-separated list of filesys?? tems or volumes which are clones of this snapshot. The clones'
origin property is this snapshot. If the clones property is not
empty, then this snapshot can not be destroyed (even with the -r or
-f options).
defer_destroy
This property is on if the snapshot has been marked for deferred
destruction by using the zfs destroy -d command. Otherwise, the
property is off.
filesystem_count
The total number of filesystems and volumes that exist under this
location in the dataset tree. This value is only available when a
filesystem_limit has been set somewhere in the tree under which the
dataset resides.
logicalreferenced
The amount of space that is "logically" accessible by this dataset.
See the referenced property. The logical space ignores the effect
of the compression and copies properties, giving a quantity closer
to the amount of data that applications see. However, it does
include space consumed by metadata.
This property can also be referred to by its shortened column name,
lrefer.
logicalused
The amount of space that is "logically" consumed by this dataset
and all its descendents. See the used property. The logical space
ignores the effect of the compression and copies properties, giving
a quantity closer to the amount of data that applications see.
However, it does include space consumed by metadata.
This property can also be referred to by its shortened column name,
lused.
mounted
For file systems, indicates whether the file system is currently
mounted. This property can be either yes or no.
origin
For cloned file systems or volumes, the snapshot from which the
clone was created. See also the clones property.
referenced
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.
This property can also be referred to by its shortened column name,
refer.
refcompressratio
The compression ratio achieved for the referenced space of this
dataset, expressed as a multiplier. See also the compressratio
property.
snapshot_count
The total number of snapshots that exist under this location in the
dataset tree. This value is only available when a snapshot_limit
has been set somewhere in the tree under which the dataset resides.
type
The type of dataset: filesystem, volume, or snapshot.
used
The amount of space consumed by this dataset and all its descen?? dents. 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 con?? sumes 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.
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.
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 fsync(2) or O_SYNC does not necessarily guarantee that the
space usage information is updated immediately.
usedby*
The usedby* properties decompose the used properties into the vari?? ous reasons that space is used. Specifically, used = usedbychildren
+ usedbydataset + usedbyrefreservation +, usedbysnapshots. These
properties are only available for datasets created on zpool "ver?? sion 13" pools.
usedbychildren
The amount of space used by children of this dataset, which would
be freed if all the dataset's children were destroyed.
usedbydataset
The amount of space used by this dataset itself, which would be
freed if the dataset were destroyed (after first removing any
refreservation and destroying any necessary snapshots or descen?? dents).
usedbyrefreservation
The amount of space used by a refreservation set on this dataset,
which would be freed if the refreservation was removed.
usedbysnapshots
The amount of space consumed by snapshots of this dataset. In par?? ticular, it is the amount of space that would be freed if all of
this dataset's snapshots were destroyed. Note that this is not sim?? ply the sum of the snapshots' used properties because space can be
shared by multiple snapshots.
userused@user
The amount of space consumed by the specified user in this dataset.
Space is charged to the owner of each file, as displayed by ls -l.
The amount of space charged is displayed by du and ls -s. See the
zfs userspace subcommand for more information.
Unprivileged users can access only their own space usage. The root
user, or a user who has been granted the userused privilege with
zfs allow, can access everyone's usage.
The userused@... properties are not displayed by zfs get all. The
user's name must be appended after the @ symbol, using one of the
following forms:
o POSIX name (for example, joe)
o POSIX numeric ID (for example, 789)
o SID name (for example, joe.smith@mydomain)
o SID numeric ID (for example, S-1-123-456-789)
userrefs
This property is set to the number of user holds on this snapshot.
User holds are set by using the zfs hold command.
groupused@group
The amount of space consumed by the specified group in this
dataset. Space is charged to the group of each file, as displayed
by ls -l. See the userused@user property for more information.
Unprivileged users can only access their own groups' space usage.
The root user, or a user who has been granted the groupused privi?? lege with zfs allow, can access all groups' usage.
volblocksize=blocksize
For volumes, specifies the block size of the volume. The blocksize
cannot be changed once the volume has been written, so it should be
set at volume creation time. The default blocksize for volumes is 8
Kbytes. Any power of 2 from 512 bytes to 128 Kbytes is valid.
This property can also be referred to by its shortened column name,
volblock.
written
The amount of referenced space written to this dataset since the
previous snapshot.
written@snapshot
The amount of referenced 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.
The snapshot may be specified as a short snapshot name (just the
part after the @), in which case it will be interpreted as a snap?? shot in the same filesystem as this dataset. The snapshot be a
full snapshot name (filesystem@snapshot), which for clones may be a
snapshot in the origin's filesystem (or the origin of the origin's
filesystem, etc).
The following native properties can be used to change the behavior of a
ZFS dataset.
aclinherit=discard | noallow | restricted | passthrough | passthrough-x
Controls how ACL entries are inherited when files and directories
are created. A file system with an aclinherit property of discard
does not inherit any ACL entries. A file system with an aclinherit
property value of noallow only inherits inheritable ACL entries
that specify "deny" permissions. The property value restricted (the
default) removes the write_acl and write_owner permissions when the
ACL entry is inherited. A file system with an aclinherit property
value of passthrough inherits all inheritable ACL entries without
any modifications made to the ACL entries when they are inherited.
A file system with an aclinherit property value of passthrough-x
has the same meaning as passthrough, except that the owner@,
group@, and everyone@ ACEs inherit the execute permission only if
the file creation mode also requests the execute bit.
When the property value is set to passthrough, files are created
with a mode determined by the inheritable ACEs. If no inheritable
ACEs exist that affect the mode, then the mode is set in accordance
to the requested mode from the application.
The aclinherit property does not apply to Posix ACLs.
acltype=noacl | posixacl
Controls whether ACLs are enabled and if so what type of ACL to
use. When a file system has the acltype property set to noacl (the
default) then ACLs are disabled. Setting the acltype property to
posixacl indicates Posix ACLs should be used. Posix ACLs are spe?? cific 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 posixacls
are supported on Linux.
To obtain the best performance when setting posixacl users are
strongly encouraged to set the xattr=sa 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 xattr=sa property. See the xattr
property for more details.
atime=on | off
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 on. See also relatime below.
canmount=on | off | noauto
If this property is set to off, the file system cannot be mounted,
and is ignored by zfs mount -a. Setting this property to off is
similar to setting the mountpoint property to none, except that the
dataset still has a normal mountpoint property, which can be inher?? ited. Setting this property to off allows datasets to be used
solely as a mechanism to inherit properties. One example of setting
canmount=off is to have two datasets with the same mountpoint, so
that the children of both datasets appear in the same directory,
but might have different inherited characteristics.
When the noauto 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 zfs
mount -a command or unmounted by the zfs unmount -a command.
This property is not inherited.
checksum=on | off | fletcher2,| fletcher4 | sha256
Controls the checksum used to verify data integrity. The default
value is on, which automatically selects an appropriate algorithm
(currently, fletcher4, but this may change in future releases). The
value off disables integrity checking on user data. Disabling
checksums is NOT a recommended practice.
Changing this property affects only newly-written data.
compression=on | off | lzjb | lz4 | gzip | gzip-N | zle
Controls the compression algorithm used for this dataset.
Setting compression to on indicates that the current default com?? pression algorithm should be used. The default balances compres?? sion 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, on does not select a fixed com?? pression 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 lzjb or, if the
lz4_compress feature is enabled, lz4.
The lzjb compression algorithm is optimized for performance while
providing decent data compression.
The lz4 compression algorithm is a high-performance replacement for
the lzjb algorithm. It features significantly faster compression
and decompression, as well as a moderately higher compression ratio
than lzjb, but can only be used on pools with the lz4_compress fea?? ture set to enabled. See zpool-features(5) for details on ZFS fea?? ture flags and the lz4_compress feature.
The gzip compression algorithm uses the same compression as the
gzip(1) command. You can specify the gzip level by using the value
gzip-N where N is an integer from 1 (fastest) to 9 (best compres?? sion ratio). Currently, gzip is equivalent to gzip-6 (which is also
the default for gzip(1)). The zle compression algorithm compresses
runs of zeros.
This property can also be referred to by its shortened column name
compress. Changing this property affects only newly-written data.
copies=1 | 2 | 3
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 used prop?? erty and counting against quotas and reservations.
Changing this property only affects newly-written data. Therefore,
set this property at file system creation time by using the -o
copies=N option.
dedup=on | off | verify | sha256[,verify]
Controls whether deduplication is in effect for a dataset. The
default value is off. The default checksum used for deduplication
is sha256 (subject to change). When dedup is enabled, the dedup
checksum algorithm overrides the checksum property. Setting the
value to verify is equivalent to specifying sha256,verify.
If the property is set to verify, 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.
Unless necessary, deduplication should NOT be enabled on a system.
See Deduplication above.
devices=on | off
Controls whether device nodes can be opened on this file system.
The default value is on.
exec=on | off
Controls whether processes can be executed from within this file
system. The default value is on.
mlslabel=label | none
The mlslabel property is a sensitivity label that determines if a
dataset can be mounted in a zone on a system with Trusted Exten?? sions enabled. If the labeled dataset matches the labeled zone, the
dataset can be mounted and accessed from the labeled zone.
When the mlslabel property is not set, the default value is none.
Setting the mlslabel property to none is equivalent to removing
the property.
The mlslabel 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 {PRIV_FILE_UPGRADE_SL} priv?? ilege is required. When changing a label to a lower label or the
default (none), the {PRIV_FILE_DOWNGRADE_SL} 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 mlslabel property to the label of that zone.
When Trusted Extensions is not enabled, only datasets with the
default label (none) can be mounted.
Zones are a Solaris feature and are not relevant on Linux.
filesystem_limit=count | none
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 zpool-features(5)).
mountpoint=path | none | legacy
Controls the mount point used for this file system. See the "Mount
Points" section for more information on how this property is used.
When the mountpoint 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 legacy, then they remain unmounted. Otherwise,
they are automatically remounted in the new location if the prop?? erty was previously legacy or none, or if they were mounted before
the property was changed. In addition, any shared file systems are
unshared and shared in the new location.
nbmand=on | off
Controls whether the file system should be mounted with nbmand (Non
Blocking mandatory locks). This is used for CIFS clients. Changes
to this property only take effect when the file system is umounted
and remounted. See mount(8) for more information on nbmand mounts.
primarycache=all | none | metadata
Controls what is cached in the primary cache (ARC). If this prop?? erty is set to all, then both user data and metadata is cached. If
this property is set to none, then neither user data nor metadata
is cached. If this property is set to metadata, then only metadata
is cached. The default value is all.
quota=size | none
Limits the amount of space a dataset and its descendents can con?? sume. This property enforces a hard limit on the amount of space
used. This includes all space consumed by descendents, including
file systems and snapshots. Setting a quota on a descendent of a
dataset 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 volsize property acts as an
implicit quota.
snapshot_limit=count | none
Limits the number of snapshots that can be created on a dataset and
its descendents. Setting a snapshot_limit on a descendent of a
dataset that already has a snapshot_limit does not override the
ancestor's snapshot_limit, but rather imposes an additional limit.
The limit is not enforced if the user is allowed to change the
limit. For example, this means that recursive snapshots taken from
the global zone are counted against each delegated dataset within a
zone. This feature must be enabled to be used (see zpool-fea?? tures(5)).
userquota@user=size | none
Limits the amount of space consumed by the specified user. Similar
to the refquota property, the userquota space calculation does not
include space that is used by descendent datasets, such as snap?? shots and clones. User space consumption is identified by the
userspace@user property.
Enforcement of user quotas may be delayed by several seconds. This
delay means that a user might exceed their quota before the system
notices that they are over quota and begins to refuse additional
writes with the EDQUOT error message . See the zfs userspace sub?? command for more information.
Unprivileged users can only access their own groups' space usage.
The root user, or a user who has been granted the userquota privi?? lege with zfs allow, can get and set everyone's quota.
This property is not available on volumes, on file systems before
version 4, or on pools before version 15. The userquota@... proper?? ties are not displayed by zfs get all. The user's name must be
appended after the @ symbol, using one of the following forms:
o POSIX name (for example, joe)
o POSIX numeric ID (for example, 789)
o SID name (for example, joe.smith@mydomain)
o SID numeric ID (for example, S-1-123-456-789)
groupquota@group=size | none
Limits the amount of space consumed by the specified group. Group
space consumption is identified by the userquota@user property.
Unprivileged users can access only their own groups' space usage.
The root user, or a user who has been granted the groupquota privi?? lege with zfs allow, can get and set all groups' quotas.
readonly=on | off
Controls whether this dataset can be modified. The default value is
off.
This property can also be referred to by its shortened column name,
rdonly.
recordsize=size
Specifies a suggested block size for files in the file system. This
property is designed solely for use with database workloads that
access files in fixed-size records. ZFS automatically tunes block
sizes according to internal algorithms optimized for typical access
patterns.
For databases that create very large files but access them in small
random chunks, these algorithms may be suboptimal. Specifying a
recordsize greater than or equal to the record size of the database
can result in significant performance gains. Use of this property
for general purpose file systems is strongly discouraged, and may
adversely affect performance.
The size specified must be a power of two greater than or equal to
512 and less than or equal to 128 Kbytes.
Changing the file system's recordsize affects only files created
afterward; existing files are unaffected.
This property can also be referred to by its shortened column name,
recsize.
redundant_metadata=all | most
Controls what types of metadata are stored redundantly. ZFS stores
an extra copy of metadata, so that if a single block is corrupted,
the amount of user data lost is limited. This extra copy is in
addition to any redundancy provided at the pool level (e.g. by mir?? roring or RAID-Z), and is in addition to an extra copy specified by
the copies property (up to a total of 3 copies). For example if
the pool is mirrored, copies=2, and redundant_metadata=most, then
ZFS stores 6 copies of most metadata, and 4 copies of data and some
metadata.
When set to all, ZFS stores an extra copy of all metadata. If a
single on-disk block is corrupt, at worst a single block of user
data (which is recordsize bytes long) can be lost.
When set to most, ZFS stores an extra copy of most types of meta?? data. This can improve performance of random writes, because less
metadata must be written. In practice, at worst about 100 blocks
(of recordsize bytes each) of user data can be lost if a single on-
disk block is corrupt. The exact behavior of which metadata blocks
are stored redundantly may change in future releases.
The default value is all.
refquota=size | none