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5135fe7110
Replace Qemu -> QEMU. Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Darren Kenny <darren.kenny@oracle.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20211118143401.4101497-1-philmd@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
211 lines
7.9 KiB
PHP
211 lines
7.9 KiB
PHP
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In addition to using normal file images for the emulated storage
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devices, QEMU can also use networked resources such as iSCSI devices.
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These are specified using a special URL syntax.
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``iSCSI``
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iSCSI support allows QEMU to access iSCSI resources directly and use
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as images for the guest storage. Both disk and cdrom images are
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supported.
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Syntax for specifying iSCSI LUNs is
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"iscsi://<target-ip>[:<port>]/<target-iqn>/<lun>"
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By default qemu will use the iSCSI initiator-name
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'iqn.2008-11.org.linux-kvm[:<name>]' but this can also be set from
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the command line or a configuration file.
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Since version QEMU 2.4 it is possible to specify a iSCSI request
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timeout to detect stalled requests and force a reestablishment of the
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session. The timeout is specified in seconds. The default is 0 which
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means no timeout. Libiscsi 1.15.0 or greater is required for this
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feature.
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Example (without authentication):
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.. parsed-literal::
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|qemu_system| -iscsi initiator-name=iqn.2001-04.com.example:my-initiator \\
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-cdrom iscsi://192.0.2.1/iqn.2001-04.com.example/2 \\
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-drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1
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Example (CHAP username/password via URL):
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.. parsed-literal::
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|qemu_system| -drive file=iscsi://user%password@192.0.2.1/iqn.2001-04.com.example/1
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Example (CHAP username/password via environment variables):
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.. parsed-literal::
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LIBISCSI_CHAP_USERNAME="user" \\
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LIBISCSI_CHAP_PASSWORD="password" \\
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|qemu_system| -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1
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``NBD``
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QEMU supports NBD (Network Block Devices) both using TCP protocol as
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well as Unix Domain Sockets. With TCP, the default port is 10809.
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Syntax for specifying a NBD device using TCP, in preferred URI form:
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"nbd://<server-ip>[:<port>]/[<export>]"
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Syntax for specifying a NBD device using Unix Domain Sockets;
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remember that '?' is a shell glob character and may need quoting:
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"nbd+unix:///[<export>]?socket=<domain-socket>"
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Older syntax that is also recognized:
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"nbd:<server-ip>:<port>[:exportname=<export>]"
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Syntax for specifying a NBD device using Unix Domain Sockets
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"nbd:unix:<domain-socket>[:exportname=<export>]"
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Example for TCP
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.. parsed-literal::
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|qemu_system| --drive file=nbd:192.0.2.1:30000
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Example for Unix Domain Sockets
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.. parsed-literal::
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|qemu_system| --drive file=nbd:unix:/tmp/nbd-socket
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``SSH``
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QEMU supports SSH (Secure Shell) access to remote disks.
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Examples:
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.. parsed-literal::
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|qemu_system| -drive file=ssh://user@host/path/to/disk.img
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|qemu_system| -drive file.driver=ssh,file.user=user,file.host=host,file.port=22,file.path=/path/to/disk.img
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Currently authentication must be done using ssh-agent. Other
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authentication methods may be supported in future.
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``GlusterFS``
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GlusterFS is a user space distributed file system. QEMU supports the
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use of GlusterFS volumes for hosting VM disk images using TCP, Unix
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Domain Sockets and RDMA transport protocols.
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Syntax for specifying a VM disk image on GlusterFS volume is
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.. parsed-literal::
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URI:
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gluster[+type]://[host[:port]]/volume/path[?socket=...][,debug=N][,logfile=...]
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JSON:
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'json:{"driver":"qcow2","file":{"driver":"gluster","volume":"testvol","path":"a.img","debug":N,"logfile":"...",
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"server":[{"type":"tcp","host":"...","port":"..."},
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{"type":"unix","socket":"..."}]}}'
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Example
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.. parsed-literal::
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URI:
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|qemu_system| --drive file=gluster://192.0.2.1/testvol/a.img,
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file.debug=9,file.logfile=/var/log/qemu-gluster.log
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JSON:
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|qemu_system| 'json:{"driver":"qcow2",
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"file":{"driver":"gluster",
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"volume":"testvol","path":"a.img",
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"debug":9,"logfile":"/var/log/qemu-gluster.log",
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"server":[{"type":"tcp","host":"1.2.3.4","port":24007},
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{"type":"unix","socket":"/var/run/glusterd.socket"}]}}'
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|qemu_system| -drive driver=qcow2,file.driver=gluster,file.volume=testvol,file.path=/path/a.img,
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file.debug=9,file.logfile=/var/log/qemu-gluster.log,
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file.server.0.type=tcp,file.server.0.host=1.2.3.4,file.server.0.port=24007,
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file.server.1.type=unix,file.server.1.socket=/var/run/glusterd.socket
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See also http://www.gluster.org.
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``HTTP/HTTPS/FTP/FTPS``
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QEMU supports read-only access to files accessed over http(s) and
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ftp(s).
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Syntax using a single filename:
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::
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<protocol>://[<username>[:<password>]@]<host>/<path>
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where:
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``protocol``
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'http', 'https', 'ftp', or 'ftps'.
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``username``
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Optional username for authentication to the remote server.
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``password``
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Optional password for authentication to the remote server.
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``host``
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Address of the remote server.
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``path``
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Path on the remote server, including any query string.
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The following options are also supported:
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``url``
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The full URL when passing options to the driver explicitly.
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``readahead``
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The amount of data to read ahead with each range request to the
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remote server. This value may optionally have the suffix 'T', 'G',
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'M', 'K', 'k' or 'b'. If it does not have a suffix, it will be
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assumed to be in bytes. The value must be a multiple of 512 bytes.
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It defaults to 256k.
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``sslverify``
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Whether to verify the remote server's certificate when connecting
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over SSL. It can have the value 'on' or 'off'. It defaults to
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'on'.
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``cookie``
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Send this cookie (it can also be a list of cookies separated by
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';') with each outgoing request. Only supported when using
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protocols such as HTTP which support cookies, otherwise ignored.
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``timeout``
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Set the timeout in seconds of the CURL connection. This timeout is
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the time that CURL waits for a response from the remote server to
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get the size of the image to be downloaded. If not set, the
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default timeout of 5 seconds is used.
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Note that when passing options to qemu explicitly, ``driver`` is the
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value of <protocol>.
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Example: boot from a remote Fedora 20 live ISO image
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.. parsed-literal::
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|qemu_system_x86| --drive media=cdrom,file=https://archives.fedoraproject.org/pub/archive/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly
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|qemu_system_x86| --drive media=cdrom,file.driver=http,file.url=http://archives.fedoraproject.org/pub/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly
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Example: boot from a remote Fedora 20 cloud image using a local
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overlay for writes, copy-on-read, and a readahead of 64k
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.. parsed-literal::
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qemu-img create -f qcow2 -o backing_file='json:{"file.driver":"http",, "file.url":"http://archives.fedoraproject.org/pub/archive/fedora/linux/releases/20/Images/x86_64/Fedora-x86_64-20-20131211.1-sda.qcow2",, "file.readahead":"64k"}' /tmp/Fedora-x86_64-20-20131211.1-sda.qcow2
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|qemu_system_x86| -drive file=/tmp/Fedora-x86_64-20-20131211.1-sda.qcow2,copy-on-read=on
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Example: boot from an image stored on a VMware vSphere server with a
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self-signed certificate using a local overlay for writes, a readahead
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of 64k and a timeout of 10 seconds.
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.. parsed-literal::
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qemu-img create -f qcow2 -o backing_file='json:{"file.driver":"https",, "file.url":"https://user:password@vsphere.example.com/folder/test/test-flat.vmdk?dcPath=Datacenter&dsName=datastore1",, "file.sslverify":"off",, "file.readahead":"64k",, "file.timeout":10}' /tmp/test.qcow2
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|qemu_system_x86| -drive file=/tmp/test.qcow2
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