*Conan The Librarian
The default format for disk volumes in the OpenVMS operating system is called the Files-11 On-Disk Structure Level 2. The default for magnetic tape volumes is based on Level 3 of the ANSI standard for magnetic tape labels and file structure for informational interchange (ANSI X3.27-1978). The INITIALIZE command can also initialize disk volumes in the Files-11 On-Disk Structure Level 1 format. You must have VOLPRO privilege to initialize a volume, except in the following cases: o A blank disk or magnetic tape volume; that is, a volume that has never been written o A disk volume that is owned by your current user identification code (UIC) or by the UIC [0,0] o A magnetic tape volume that allows write (W) access to your current UIC that was not protected when it was initialized After the volume is initialized and mounted, the SET SECURITY command may be used to modify the security profile. When you initialize a disk volume, the caching attribute of its root directory (000000.DIR;1) is set to write-through. This means that by default, all the files and directories that you create in the volume will inherit a caching attribute of write-through. To change the caching attribute, use the SET FILE command with the /CACHING_ATTRIBUTE qualifier. When the INITIALIZE command initializes a magnetic tape volume, it always attempts to read the volume. A blank magnetic tape can sometimes cause unrecoverable errors, such as the following: o An invalid volume number error message: %INIT-F-VOLINV, volume is invalid o A runaway magnetic tape (this frequently occurs with new magnetic tapes that have never been written or that have been run through verifying machines). You can stop a runaway magnetic tape only by setting the magnetic tape drive off line and by then putting it back on line. If this type of unrecoverable error occurs, you can initialize a magnetic tape successfully by repeating the INITIALIZE command from an account that has VOLPRO (volume protection) privilege and by specifying the following qualifier in the command: /OVERRIDE=(ACCESSIBILITY,EXPIRATION) This qualifier ensures that the INITIALIZE command does not attempt to verify any labels on the magnetic tape. If you have VOLPRO privilege, the INITIALIZE command initializes a disk without reading the ownership information. If you do not have VOLPRO privilege, the INITIALIZE command checks the ownership of the volume before initializing the disk. A blank disk or a disk with an incorrect format can sometimes cause a fatal drive error. If a blank disk or a disk with an incorrect format causes this type of error, you can initialize a disk successfully by repeating the INITIALIZE command with the /DENSITY qualifier from an account that has VOLPRO privilege. Many of the INITIALIZE command qualifiers allow you to specify parameters that can maximize input/output (I/O) efficiency.