
 Virtual disks have all the performance characteristics  of  physical  disks.
 They exist on a  physical  disk  within  a  'container  file',  which  is  a
 contiguous file, whose number of blocks determines the size of  the  virtual
 disk. One container file is required for each virtual disk.  On this system,
 the container files are located on DR0:[1,76].  This is not  a  requirement.
 Virtual disks are mounted and dismounted just like any other file structured
 device. They must be initialized to create a home block and index structure,
 again just like any other  disk.  Once  created  and  mounted,  they  behave
 just as would a 'real' disk and answer to the device mnemonic and unit VDn:.

 For help in using an existing virtual disk, type HELP VIRTUAL_DISK USAGE

 For help in creating virtual disk from scratch, type HELP VIRTUAL_DISK CREATE

 Help is available on the virtual disk utilities.  Type HELP AVD or HELP DVD

2 USAGE

 Existing virtual disks are allocated and mounted by:

	AVD VDn:=DR:[1,76]<filename>
	MOU VDn:/OVR

 where <filename> is the name of the container file for the virtual disk.

 Existing virtual disks are deallocated and demounted by:

	DMO VDn:/DEV
	DVD VDn:

2 CREATE

 To create a virtual disk from scratch:

	AVD VDn:=DR:[1,76]<filnam>/CR:<blocks>
	SET /NOPUB=VDn:
	ALL VDn:
	MOU VDn:/FOR
	INI VDn:<volnam>
	DMO VDn:/DEV
	DEA VDn:
	SET /PUB=VDn:
	MOU VDn:/OVR

where <filnam>  is the container file to create.  (extension defaults to .DSK)
      <blocks>  is the decimal number of blocks to allocate the container file
      <volnam>  is the volume id for the virtual disk
                (normally the same as <filnam> to avoid confusion)

