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diff --git a/qemu-doc.texi b/qemu-doc.texi index f7317dfc66..69e2953dc6 100644 --- a/qemu-doc.texi +++ b/qemu-doc.texi @@ -245,6 +245,222 @@ targets do not need a disk image. @c man end +@subsection Device URL Syntax +@c TODO merge this with section Disk Images + +@c man begin NOTES + +In addition to using normal file images for the emulated storage devices, +QEMU can also use networked resources such as iSCSI devices. These are +specified using a special URL syntax. + +@table @option +@item iSCSI +iSCSI support allows QEMU to access iSCSI resources directly and use as +images for the guest storage. Both disk and cdrom images are supported. + +Syntax for specifying iSCSI LUNs is +``iscsi://<target-ip>[:<port>]/<target-iqn>/<lun>'' + +By default qemu will use the iSCSI initiator-name +'iqn.2008-11.org.linux-kvm[:<name>]' but this can also be set from the command +line or a configuration file. + +Since version Qemu 2.4 it is possible to specify a iSCSI request timeout to detect +stalled requests and force a reestablishment of the session. The timeout +is specified in seconds. The default is 0 which means no timeout. Libiscsi +1.15.0 or greater is required for this feature. + +Example (without authentication): +@example +qemu-system-i386 -iscsi initiator-name=iqn.2001-04.com.example:my-initiator \ + -cdrom iscsi://192.0.2.1/iqn.2001-04.com.example/2 \ + -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1 +@end example + +Example (CHAP username/password via URL): +@example +qemu-system-i386 -drive file=iscsi://user%password@@192.0.2.1/iqn.2001-04.com.example/1 +@end example + +Example (CHAP username/password via environment variables): +@example +LIBISCSI_CHAP_USERNAME="user" \ +LIBISCSI_CHAP_PASSWORD="password" \ +qemu-system-i386 -drive file=iscsi://192.0.2.1/iqn.2001-04.com.example/1 +@end example + +@item NBD +QEMU supports NBD (Network Block Devices) both using TCP protocol as well +as Unix Domain Sockets. + +Syntax for specifying a NBD device using TCP +``nbd:<server-ip>:<port>[:exportname=<export>]'' + +Syntax for specifying a NBD device using Unix Domain Sockets +``nbd:unix:<domain-socket>[:exportname=<export>]'' + +Example for TCP +@example +qemu-system-i386 --drive file=nbd:192.0.2.1:30000 +@end example + +Example for Unix Domain Sockets +@example +qemu-system-i386 --drive file=nbd:unix:/tmp/nbd-socket +@end example + +@item SSH +QEMU supports SSH (Secure Shell) access to remote disks. + +Examples: +@example +qemu-system-i386 -drive file=ssh://user@@host/path/to/disk.img +qemu-system-i386 -drive file.driver=ssh,file.user=user,file.host=host,file.port=22,file.path=/path/to/disk.img +@end example + +Currently authentication must be done using ssh-agent. Other +authentication methods may be supported in future. + +@item Sheepdog +Sheepdog is a distributed storage system for QEMU. +QEMU supports using either local sheepdog devices or remote networked +devices. + +Syntax for specifying a sheepdog device +@example +sheepdog[+tcp|+unix]://[host:port]/vdiname[?socket=path][#snapid|#tag] +@end example + +Example +@example +qemu-system-i386 --drive file=sheepdog://192.0.2.1:30000/MyVirtualMachine +@end example + +See also @url{https://sheepdog.github.io/sheepdog/}. + +@item GlusterFS +GlusterFS is a user space distributed file system. +QEMU supports the use of GlusterFS volumes for hosting VM disk images using +TCP, Unix Domain Sockets and RDMA transport protocols. + +Syntax for specifying a VM disk image on GlusterFS volume is +@example + +URI: +gluster[+type]://[host[:port]]/volume/path[?socket=...][,debug=N][,logfile=...] + +JSON: +'json:@{"driver":"qcow2","file":@{"driver":"gluster","volume":"testvol","path":"a.img","debug":N,"logfile":"...", +@ "server":[@{"type":"tcp","host":"...","port":"..."@}, +@ @{"type":"unix","socket":"..."@}]@}@}' +@end example + + +Example +@example +URI: +qemu-system-x86_64 --drive file=gluster://192.0.2.1/testvol/a.img, +@ file.debug=9,file.logfile=/var/log/qemu-gluster.log + +JSON: +qemu-system-x86_64 'json:@{"driver":"qcow2", +@ "file":@{"driver":"gluster", +@ "volume":"testvol","path":"a.img", +@ "debug":9,"logfile":"/var/log/qemu-gluster.log", +@ "server":[@{"type":"tcp","host":"1.2.3.4","port":24007@}, +@ @{"type":"unix","socket":"/var/run/glusterd.socket"@}]@}@}' +qemu-system-x86_64 -drive driver=qcow2,file.driver=gluster,file.volume=testvol,file.path=/path/a.img, +@ file.debug=9,file.logfile=/var/log/qemu-gluster.log, +@ file.server.0.type=tcp,file.server.0.host=1.2.3.4,file.server.0.port=24007, +@ file.server.1.type=unix,file.server.1.socket=/var/run/glusterd.socket +@end example + +See also @url{http://www.gluster.org}. + +@item HTTP/HTTPS/FTP/FTPS +QEMU supports read-only access to files accessed over http(s) and ftp(s). + +Syntax using a single filename: +@example +<protocol>://[<username>[:<password>]@@]<host>/<path> +@end example + +where: +@table @option +@item protocol +'http', 'https', 'ftp', or 'ftps'. + +@item username +Optional username for authentication to the remote server. + +@item password +Optional password for authentication to the remote server. + +@item host +Address of the remote server. + +@item path +Path on the remote server, including any query string. +@end table + +The following options are also supported: +@table @option +@item url +The full URL when passing options to the driver explicitly. + +@item readahead +The amount of data to read ahead with each range request to the remote server. +This value may optionally have the suffix 'T', 'G', 'M', 'K', 'k' or 'b'. If it +does not have a suffix, it will be assumed to be in bytes. The value must be a +multiple of 512 bytes. It defaults to 256k. + +@item sslverify +Whether to verify the remote server's certificate when connecting over SSL. It +can have the value 'on' or 'off'. It defaults to 'on'. + +@item cookie +Send this cookie (it can also be a list of cookies separated by ';') with +each outgoing request. Only supported when using protocols such as HTTP +which support cookies, otherwise ignored. + +@item timeout +Set the timeout in seconds of the CURL connection. This timeout is the time +that CURL waits for a response from the remote server to get the size of the +image to be downloaded. If not set, the default timeout of 5 seconds is used. +@end table + +Note that when passing options to qemu explicitly, @option{driver} is the value +of <protocol>. + +Example: boot from a remote Fedora 20 live ISO image +@example +qemu-system-x86_64 --drive media=cdrom,file=http://dl.fedoraproject.org/pub/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly + +qemu-system-x86_64 --drive media=cdrom,file.driver=http,file.url=http://dl.fedoraproject.org/pub/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso,readonly +@end example + +Example: boot from a remote Fedora 20 cloud image using a local overlay for +writes, copy-on-read, and a readahead of 64k +@example +qemu-img create -f qcow2 -o backing_file='json:@{"file.driver":"http",, "file.url":"https://dl.fedoraproject.org/pub/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 + +qemu-system-x86_64 -drive file=/tmp/Fedora-x86_64-20-20131211.1-sda.qcow2,copy-on-read=on +@end example + +Example: boot from an image stored on a VMware vSphere server with a self-signed +certificate using a local overlay for writes, a readahead of 64k and a timeout +of 10 seconds. +@example +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 + +qemu-system-x86_64 -drive file=/tmp/test.qcow2 +@end example + +@end table + +@c man end + @node pcsys_keys @section Keys in the graphical frontends |