--------------------- XL DISK CONFIGURATION --------------------- This document specifies the xl config file format disk configuration option. It has the following form: disk = [ '', '', ... ] where each diskspec is in this form: [=|,]*, [, [, [, []]]], [=|,]* [target=] For example, these strings are equivalent: /dev/vg/guest-volume,,hda /dev/vg/guest-volume,raw,hda,rw format=raw, vdev=hda, access=rw, target=/dev/vg/guest-volume raw:/dev/vg/guest-volume,hda,w (deprecated, see below) As are these: /root/image.iso,,hdc,cdrom /root/image.iso,,hdc,,cdrom /root/image.iso,raw,hdc,devtype=cdrom format=raw, vdev=hdc, access=ro, devtype=cdrom, target=/root/image.iso raw:/root/image.iso,hdc:cdrom,ro (deprecated, see below) These might be specified in the domain config file like this: disk = [ '/dev/vg/guest-volume,,hda', '/root/image.iso,,hdc,cdrom' ] More formally, the string is a series of comma-separated keyword/value pairs, flags and positional parameters. Parameters which are not bare keywords and which do not contain "=" symbols are assigned to the so-far-unspecified positional parameters, in the order below. The positional parameters may also be specified explicitly by name. Each parameter may be specified at most once, either as a positional parameter or a named parameter. Default values apply if the parameter is not specified, or if it is specified with an empty value (whether positionally or explicitly). Whitespace may appear before each parameter and will be ignored. ===================== POSITIONAL PARAMETERS ===================== target ------ Description: Block device or image file path. When this is used as a path, /dev will be prepended if the path doesn't start with a '/'. Supported values: N/A Deprecated values: N/A Default value: None. While a path is provided in most cases there is an exception: for a cdrom device, lack of this attribute would imply an empty cdrom drive. Special syntax: When this parameter is specified by name, ie with the "target=" syntax in the configuration file, it consumes the whole rest of the including trailing whitespaces. Therefore in that case it must come last. This is permissible even if an empty value for the target was already specified as a positional parameter. This is the only way to specify a target string containing metacharacters such as commas and (in some cases) colons, which would otherwise be misinterpreted. Future parameter and flag names will start with an ascii letter and contain only ascii alphanumerics, hyphens and underscores, and will not be legal as vdevs. Targets which might match that syntax should not be specified as positional parameters. format ------ Description: Specifies the format of image file. Supported values: raw, qcow, qcow2, vhd Deprecated values: None Default value: raw vdev ---- Description: Virtual device as seen by the guest (also referred to as guest drive designation in some specifications). See docs/misc/vbd-interface.txt. Supported values: hd[x], xvd[x], sd[x] etc. Please refer to the above specification for further details. Deprecated values: None Default Value: None, this parameter is mandatory. access ------- Description: Specified access control information. Whether or not the block device is provided to the guest in read-only or read-write mode depends on this attribute. Supported values: ro, r (specifies read-only) rw, w (specifies read/write) Deprecated values: None Default value: rw unless devtype=cdrom, in which case r ========================== OTHER PARAMETERS AND FLAGS ========================== devtype= ----------------- Description: Qualifies virtual device type. Supported values: cdrom Deprecated values: None Mandatory: No cdrom ----- Convenience alias for "devtype=cdrom". backend= --------------------- Description: Designates a backend domain for the device Supported values: Valid domain names Mandatory: No Specifies the backend domain which this device should attach to. This defaults to domain 0. Specifying another domain requires setting up a driver domain which is outside the scope of this document. backendtype= -------------------------- Description: Specifies the backend implementation to use Supported values: phy, tap, qdisk Mandatory: No Default value: Automatically determine which backend to use. This does not affect the guest's view of the device. It controls which software implementation of the Xen backend driver is used. Not all backend drivers support all combinations of other options. For example, "phy" does not support formats other than "raw". Normally this option should not be specified, in which case libxl will automatically determine the most suitable backend. script=