ZFS-RECEIVE(8) FreeBSD System Manager's Manual ZFS-RECEIVE(8)
NAME
zfs-receive - create snapshot from backup stream
SYNOPSIS
zfs receive [-FhMnsuv] [-o origin=snapshot] [-o property=value]
[-x property] filesystem|volume|snapshot
zfs receive [-FhMnsuv] [-d|-e] [-o origin=snapshot] [-o property=value]
[-x property] filesystem
zfs receive -A filesystem|volume
DESCRIPTION
zfs receive [-FhMnsuv] [-o origin=snapshot] [-o property=value] [-x
property] filesystem|volume|snapshot
zfs receive [-FhMnsuv] [-d|-e] [-o origin=snapshot] [-o property=value]
[-x property] filesystem
Creates a snapshot whose contents are as specified in the stream
provided on standard input. If a full stream is received, then a new
file system is created as well. Streams are created using the zfs send
subcommand, which by default creates a full stream. zfs recv can be
used as an alias for zfs receive.
If an incremental stream is received, then the destination file system
must already exist, and its most recent snapshot must match the
incremental stream's source. For zvols, the destination device link is
destroyed and recreated, which means the zvol cannot be accessed during
the receive operation.
When a snapshot replication package stream that is generated by using
the zfs send -R command is received, any snapshots that do not exist on
the sending location are destroyed by using the zfs destroy -d command.
The ability to send and receive deduplicated send streams has been
removed. However, a deduplicated send stream created with older
software can be converted to a regular (non-deduplicated) stream by
using the zstream redup command.
If -o property=value or -x property is specified, it applies to the
effective value of the property throughout the entire subtree of
replicated datasets. Effective property values will be set (-o) or
inherited (-x) on the topmost in the replicated subtree. In descendant
datasets, if the property is set by the send stream, it will be
overridden by forcing the property to be inherited from the top-most
file system. Received properties are retained in spite of being
overridden and may be restored with zfs inherit -S. Specifying -o
origin=snapshot is a special case because, even if origin is a read-
only property and cannot be set, it's allowed to receive the send
stream as a clone of the given snapshot.
Raw encrypted send streams (created with zfs send -w) may only be
received as is, and cannot be re-encrypted, decrypted, or recompressed
by the receive process. Unencrypted streams can be received as
encrypted datasets, either through inheritance or by specifying
encryption parameters with the -o options. Note that the keylocation
property cannot be overridden to prompt during a receive. This is
because the receive process itself is already using the standard input
for the send stream. Instead, the property can be overridden after the
receive completes.
The added security provided by raw sends adds some restrictions to the
send and receive process. ZFS will not allow a mix of raw receives and
non-raw receives. Specifically, any raw incremental receives that are
attempted after a non-raw receive will fail. Non-raw receives do not
have this restriction and, therefore, are always possible. Because of
this, it is best practice to always use either raw sends for their
security benefits or non-raw sends for their flexibility when working
with encrypted datasets, but not a combination.
The reason for this restriction stems from the inherent restrictions of
the AEAD ciphers that ZFS uses to encrypt data. When using ZFS native
encryption, each block of data is encrypted against a randomly
generated number known as the "initialization vector" (IV), which is
stored in the filesystem metadata. This number is required by the
encryption algorithms whenever the data is to be decrypted. Together,
all of the IVs provided for all of the blocks in a given snapshot are
collectively called an "IV set". When ZFS performs a raw send, the IV
set is transferred from the source to the destination in the send
stream. When ZFS performs a non-raw send, the data is decrypted by the
source system and re-encrypted by the destination system, creating a
snapshot with effectively the same data, but a different IV set. In
order for decryption to work after a raw send, ZFS must ensure that the
IV set used on both the source and destination side match. When an
incremental raw receive is performed on top of an existing snapshot,
ZFS will check to confirm that the "from" snapshot on both the source
and destination were using the same IV set, ensuring the new IV set is
consistent.
The name of the snapshot (and file system, if a full stream is
received) that this subcommand creates depends on the argument type and
the use of the -d or -e options.
If the argument is a snapshot name, the specified snapshot is created.
If the argument is a file system or volume name, a snapshot with the
same name as the sent snapshot is created within the specified
filesystem or volume. If neither of the -d or -e options are
specified, the provided target snapshot name is used exactly as
provided.
The -d and -e options cause the file system name of the target snapshot
to be determined by appending a portion of the sent snapshot's name to
the specified target filesystem. If the -d option is specified, all
but the first element of the sent snapshot's file system path (usually
the pool name) is used and any required intermediate file systems
within the specified one are created. If the -e option is specified,
then only the last element of the sent snapshot's file system name
(i.e. the name of the source file system itself) is used as the target
file system name.
-F Force a rollback of the file system to the most recent snapshot
before performing the receive operation. If receiving an
incremental replication stream (for example, one generated by zfs
send -R [-i|-I]), destroy snapshots and file systems that do not
exist on the sending side.
-d Discard the first element of the sent snapshot's file system name,
using the remaining elements to determine the name of the target
file system for the new snapshot as described in the paragraph
above.
-e Discard all but the last element of the sent snapshot's file system
name, using that element to determine the name of the target file
system for the new snapshot as described in the paragraph above.
-h Skip the receive of holds. There is no effect if holds are not
sent.
-M Force an unmount of the file system while receiving a snapshot.
This option is not supported on Linux.
-n Do not actually receive the stream. This can be useful in
conjunction with the -v option to verify the name the receive
operation would use.
-o origin=snapshot
Forces the stream to be received as a clone of the given snapshot.
If the stream is a full send stream, this will create the
filesystem described by the stream as a clone of the specified
snapshot. Which snapshot was specified will not affect the success
or failure of the receive, as long as the snapshot does exist. If
the stream is an incremental send stream, all the normal
verification will be performed.
-o property=value
Sets the specified property as if the command zfs set
property=value was invoked immediately before the receive. When
receiving a stream from zfs send -R, causes the property to be
inherited by all descendant datasets, as through zfs inherit
property was run on any descendant datasets that have this property
set on the sending system.
If the send stream was sent with -c then overriding the compression
property will have no affect on received data but the compression
property will be set. To have the data recompressed on receive
remove the -c flag from the send stream.
Any editable property can be set at receive time. Set-once
properties bound to the received data, such as normalization and
casesensitivity, cannot be set at receive time even when the
datasets are newly created by zfs receive. Additionally both
settable properties version and volsize cannot be set at receive
time.
The -o option may be specified multiple times, for different
properties. An error results if the same property is specified in
multiple -o or -x options.
The -o option may also be used to override encryption properties
upon initial receive. This allows unencrypted streams to be
received as encrypted datasets. To cause the received dataset (or
root dataset of a recursive stream) to be received as an encryption
root, specify encryption properties in the same manner as is
required for zfs create. For instance:
# zfs send tank/test@snap1 | zfs recv -o encryption=on -o
keyformat=passphrase -o keylocation=file:///path/to/keyfile
Note that -o keylocation=prompt may not be specified here, since
the standard input is already being utilized for the send stream.
Once the receive has completed, you can use zfs set to change this
setting after the fact. Similarly, you can receive a dataset as an
encrypted child by specifying -x encryption to force the property
to be inherited. Overriding encryption properties (except for
keylocation) is not possible with raw send streams.
-s If the receive is interrupted, save the partially received state,
rather than deleting it. Interruption may be due to premature
termination of the stream (e.g. due to network failure or failure
of the remote system if the stream is being read over a network
connection), a checksum error in the stream, termination of the zfs
receive process, or unclean shutdown of the system.
The receive can be resumed with a stream generated by zfs send -t
token, where the token is the value of the receive_resume_token
property of the filesystem or volume which is received into.
To use this flag, the storage pool must have the extensible_dataset
feature enabled. See zpool-features(7) for details on ZFS feature
flags.
-u File system that is associated with the received stream is not
mounted.
-v Print verbose information about the stream and the time required to
perform the receive operation.
-x property
Ensures that the effective value of the specified property after
the receive is unaffected by the value of that property in the send
stream (if any), as if the property had been excluded from the send
stream.
If the specified property is not present in the send stream, this
option does nothing.
If a received property needs to be overridden, the effective value
will be set or inherited, depending on whether the property is
inheritable or not.
In the case of an incremental update, -x leaves any existing local
setting or explicit inheritance unchanged.
All -o restrictions (e.g. set-once) apply equally to -x.
zfs receive -A filesystem|volume
Abort an interrupted zfs receive -s, deleting its saved partially
received state.
SEE ALSO
zfs-send(8), zstream(8)
FreeBSD 13.1-RELEASE-p6 February 16, 2020 FreeBSD 13.1-RELEASE-p6
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