c23874132b
The preferred syntax is to use "foo=on|off", rather than a bare "foo" or "nofoo". Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Message-Id: <20210216191027.595031-8-berrange@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
149 lines
5.4 KiB
ReStructuredText
149 lines
5.4 KiB
ReStructuredText
QEMU Storage Daemon
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===================
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Synopsis
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--------
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**qemu-storage-daemon** [options]
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Description
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-----------
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qemu-storage-daemon provides disk image functionality from QEMU, qemu-img, and
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qemu-nbd in a long-running process controlled via QMP commands without running
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a virtual machine. It can export disk images, run block job operations, and
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perform other disk-related operations. The daemon is controlled via a QMP
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monitor and initial configuration from the command-line.
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The daemon offers the following subset of QEMU features:
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* Block nodes
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* Block jobs
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* Block exports
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* Throttle groups
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* Character devices
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* Crypto and secrets
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* QMP
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* IOThreads
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Commands can be sent over a QEMU Monitor Protocol (QMP) connection. See the
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:manpage:`qemu-storage-daemon-qmp-ref(7)` manual page for a description of the
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commands.
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The daemon runs until it is stopped using the ``quit`` QMP command or
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SIGINT/SIGHUP/SIGTERM.
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**Warning:** Never modify images in use by a running virtual machine or any
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other process; this may destroy the image. Also, be aware that querying an
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image that is being modified by another process may encounter inconsistent
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state.
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Options
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-------
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.. program:: qemu-storage-daemon
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Standard options:
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.. option:: -h, --help
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Display help and exit
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.. option:: -V, --version
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Display version information and exit
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.. option:: -T, --trace [[enable=]PATTERN][,events=FILE][,file=FILE]
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.. include:: ../qemu-option-trace.rst.inc
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.. option:: --blockdev BLOCKDEVDEF
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is a block node definition. See the :manpage:`qemu(1)` manual page for a
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description of block node properties and the :manpage:`qemu-block-drivers(7)`
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manual page for a description of driver-specific parameters.
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.. option:: --chardev CHARDEVDEF
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is a character device definition. See the :manpage:`qemu(1)` manual page for
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a description of character device properties. A common character device
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definition configures a UNIX domain socket::
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--chardev socket,id=char1,path=/tmp/qmp.sock,server=on,wait=off
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.. option:: --export [type=]nbd,id=<id>,node-name=<node-name>[,name=<export-name>][,writable=on|off][,bitmap=<name>]
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--export [type=]vhost-user-blk,id=<id>,node-name=<node-name>,addr.type=unix,addr.path=<socket-path>[,writable=on|off][,logical-block-size=<block-size>][,num-queues=<num-queues>]
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--export [type=]vhost-user-blk,id=<id>,node-name=<node-name>,addr.type=fd,addr.str=<fd>[,writable=on|off][,logical-block-size=<block-size>][,num-queues=<num-queues>]
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is a block export definition. ``node-name`` is the block node that should be
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exported. ``writable`` determines whether or not the export allows write
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requests for modifying data (the default is off).
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The ``nbd`` export type requires ``--nbd-server`` (see below). ``name`` is
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the NBD export name. ``bitmap`` is the name of a dirty bitmap reachable from
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the block node, so the NBD client can use NBD_OPT_SET_META_CONTEXT with the
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metadata context name "qemu:dirty-bitmap:BITMAP" to inspect the bitmap.
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The ``vhost-user-blk`` export type takes a vhost-user socket address on which
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it accept incoming connections. Both
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``addr.type=unix,addr.path=<socket-path>`` for UNIX domain sockets and
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``addr.type=fd,addr.str=<fd>`` for file descriptor passing are supported.
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``logical-block-size`` sets the logical block size in bytes (the default is
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512). ``num-queues`` sets the number of virtqueues (the default is 1).
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.. option:: --monitor MONITORDEF
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is a QMP monitor definition. See the :manpage:`qemu(1)` manual page for
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a description of QMP monitor properties. A common QMP monitor definition
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configures a monitor on character device ``char1``::
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--monitor chardev=char1
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.. option:: --nbd-server addr.type=inet,addr.host=<host>,addr.port=<port>[,tls-creds=<id>][,tls-authz=<id>][,max-connections=<n>]
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--nbd-server addr.type=unix,addr.path=<path>[,tls-creds=<id>][,tls-authz=<id>][,max-connections=<n>]
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is a server for NBD exports. Both TCP and UNIX domain sockets are supported.
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TLS encryption can be configured using ``--object`` tls-creds-* and authz-*
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secrets (see below).
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To configure an NBD server on UNIX domain socket path ``/tmp/nbd.sock``::
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--nbd-server addr.type=unix,addr.path=/tmp/nbd.sock
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.. option:: --object help
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--object <type>,help
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--object <type>[,<property>=<value>...]
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is a QEMU user creatable object definition. List object types with ``help``.
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List object properties with ``<type>,help``. See the :manpage:`qemu(1)`
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manual page for a description of the object properties.
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Examples
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--------
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Launch the daemon with QMP monitor socket ``qmp.sock`` so clients can execute
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QMP commands::
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$ qemu-storage-daemon \
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--chardev socket,path=qmp.sock,server=on,wait=off,id=char1 \
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--monitor chardev=char1
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Export raw image file ``disk.img`` over NBD UNIX domain socket ``nbd.sock``::
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$ qemu-storage-daemon \
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--blockdev driver=file,node-name=disk,filename=disk.img \
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--nbd-server addr.type=unix,addr.path=nbd.sock \
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--export type=nbd,id=export,node-name=disk,writable=on
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Export a qcow2 image file ``disk.qcow2`` as a vhosts-user-blk device over UNIX
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domain socket ``vhost-user-blk.sock``::
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$ qemu-storage-daemon \
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--blockdev driver=file,node-name=file,filename=disk.qcow2 \
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--blockdev driver=qcow2,node-name=qcow2,file=file \
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--export type=vhost-user-blk,id=export,addr.type=unix,addr.path=vhost-user-blk.sock,node-name=qcow2
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See also
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--------
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:manpage:`qemu(1)`, :manpage:`qemu-block-drivers(7)`, :manpage:`qemu-storage-daemon-qmp-ref(7)`
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