Provided by: zfsutils-linux_2.2.6-1ubuntu2_amd64 
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
zfs receive -c [-vn] filesystem|snapshot
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 effect 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.
zfs receive -c [-vn] filesystem|snapshot
Attempt to repair data corruption in the specified dataset, by using the provided stream
as the source of healthy data. This method of healing can only heal data blocks present
in the stream. Metadata can not be healed by corrective receive. Running a scrub is
recommended post-healing to ensure all data corruption was repaired.
It's important to consider why corruption has happened in the first place. If you have
slowly failing hardware - periodically repairing the data is not going to save you from
data loss later on when the hardware fails completely.
EXAMPLES
Example 1: Remotely Replicating ZFS Data
The following commands send a full stream and then an incremental stream to a remote
machine, restoring them into poolB/received/fs@a and poolB/received/fs@b, respectively.
poolB must contain the file system poolB/received, and must not initially contain
poolB/received/fs.
# zfs send pool/fs@a |
ssh host zfs receive poolB/received/fs@a
# zfs send -i a pool/fs@b |
ssh host zfs receive poolB/received/fs
Example 2: Using the zfs receive -d Option
The following command sends a full stream of poolA/fsA/fsB@snap to a remote machine,
receiving it into poolB/received/fsA/fsB@snap. The fsA/fsB@snap portion of the received
snapshot's name is determined from the name of the sent snapshot. poolB must contain the
file system poolB/received. If poolB/received/fsA does not exist, it is created as an empty
file system.
# zfs send poolA/fsA/fsB@snap |
ssh host zfs receive -d poolB/received
SEE ALSO
zfs-send(8), zstream(8)