HP OpenVMS System Manager's Manual, Volume 1:...

Managing Storage Media

Allocating and Deallocating Drives

Protecting Volumes

Initializing Volumes  

• To delete all old information from the volume.



• To give the volume a structure that is recognized by the operating system.
  
  This structure prepares a volume to receive data and stores it so that the operating system can locate it easily.

Before you or any user can write files or data to a disk, tape, or CD-ROM volume, you must set up that volume. The steps for doing this are somewhat different for disk and tape volumes or for CD-ROM volumes, as explained in the next two sections.

Steps for Setting Up Disk or Tape Volumes

To set up a disk or tape volume, you need to perform two steps. In each step you enter a DCL command, as follows:

1. INITIALIZE	Formats the volume and writes an identifying label on it. This effectively removes the previous contents of the volume. (Initializing a volume each time you use it is not necessary.)
2. MOUNT	Provides the user's process with access to a volume's files or data.

Initializing a disk volume removes links to existing files on the volume, which, in effect, deletes (but does not erase) the files. To erase the data in a file, use the INITIALIZE/ERASE command. Do not initialize a volume that contains data that users want to keep. (Initializing a volume each time you use it is not necessary.)

Steps for Setting Up CD-ROM Volumes

To set up a CD-ROM volume using an OpenVMS CD-RW drive, you need to follow these steps:

1. Run CDRECORD.COM	Replaces the INITIALIZE command in the "Steps for Setting Up Disk or Tape Volumes" section.
2. MOUNT	Provides the user's process with access to a volume's files or data.

For more information about running CDRECORD.COM, see Creating a CD-ROM.

Setting Up Media on a Workstation

For workstations with removable media, users can perform the tasks shown in Tasks Users Can Perform Unassisted unassisted.

Table 7   Tasks Users Can Perform Unassisted

Task	Description
Load	Insert the media into the drive.
Initialize	Remove all previous contents from the media. (VOLPRO privilege is required for most operations.)
Mount	Logically mount the media and allocate the device (requires SYSNAM, GRPNAM, or VOLPRO privilege for various operations). To mount a volume on a device, you must have read (R), write (W), or control (C) access to that device.
Perform file operations	Access files and perform the desired operations on them.
Dismount	Logically dismount the media and deallocate the device (requires GRPNAM and SYSNAM user privileges to dismount group and system volumes).
Unload	Remove the media from the drive compartment.

For additional information about manipulating removable media on your workstation, refer to the hardware manuals that accompany your workstation.

On VAX systems, also refer to the upgrade and installation supplement for your computer.

Using the INITIALIZE Command  

Use the DCL command INITIALIZE to format and write a label to the volume. To initialize a disk or tape volume, enter the INITIALIZE command using the following format:INITIALIZE device-name[:] volume-label

where:

device-name	Specifies the name of the device on which the volume is to be physically mounted and then initialized. To prevent initializing another user's volume, allocate a device before you initialize the volume. (Prior allocation is not required, however.)
volume-label	Specifies the identification to be encoded on the volume. For a disk volume, you can specify a maximum of 12 ANSI characters; for a magnetic tape volume, you can specify a maxiumum of 6 alphanumeric characters.

To initialize a public volume, you must specify the /SYSTEM qualifier with the DCL command INITIALIZE:INITIALIZE/SYSTEM device name[:] volume-label

For more details on INITIALIZE command format, refer to the HP OpenVMS DCL Dictionary.

Examples

1. $ INITIALIZE DUA2: TEMP

   The command in this example initializes the disk volume DUA2: and labels the volume TEMP.

2. $ INITIALIZE MUB2: TEST

   The command in this example initializes the tape volume on MUB2: and labels the volume TEST.

The OpenVMS User's Manual contains additional examples of the INITIALIZE command.

Using INITIALIZE Command Qualifiers  

INITIALIZE Command Qualifiers describes a number of qualifiers you can use with the INITIALIZE command. Selecting appropriate values for these qualifiers and selecting the appropriate position for the index file involve tradeoffs. The HP OpenVMS DCL Dictionary contains more information about each qualifier.

Table 8   INITIALIZE Command Qualifiers

Qualifier	Description
/CLUSTER_SIZE= number-of-blocks	Specifies minimum allocation unit in blocks.
/HEADERS= number-of-headers	Specifies the number of file entries, called file headers, that you expect to have in INDEXF.SYS, the index file. It controls how much space is initially allocated to INDEXF.SYS for headers. (The system accesses the index file each time it locates a file on disk.) Each file on a disk requires at least 1 file header and each header occupies 1 block within INDEXF.SYS. Files that have many access control entries (ACEs) or that are very fragmented might use more than 1 header. The default value of 16 leaves room for fewer than 10 files to be created before INDEXF.SYS must extend. Therefore, estimate the total number of files that will be created on the disk and specify it here. A good estimate improves performance of disk access. Setting the number too low can result in a fragmented index file. However, if you set the number too high, space allocated to headers cannot be made available later for file storage and can lead to wasted disk space. This value cannot be changed without reinitializing the volume. INDEXF.SYS is limited as to how many times it can extend. When the map area in its header (where the retrieval pointers are stored) becomes full, files cannot be created and the message SYSTEM-W-HEADERFULL is displayed.
/INDEX=position	Determines the location of the index file on a volume, using the keyword BEGINNING, MIDDLE, END, or BLOCK:n. The index file lists the names and addresses of all disk files, so it is constantly referenced.
/MAXIMUM_FILES=n	Specifies the maximum number of entries in the index file, and therefore limits the number of files that a volume can contain. Once set, the maximum number of files for a volume cannot be increased without reinitializing the disk.
/PROTECTION= (ownership=[:access][,...])	Specifies the protection code to be assigned to a volume. See Protecting Volumes for details.
/WINDOWS=n	Sets the default number of mapping pointers to be allocated for file windows. When a file is opened, the file system uses mapping pointers to access data in the file. The file system can read one file segment into memory for each available pointer.

The default value for the /HEADER qualifier is generally insufficient for ODS-2 disks. To improve performance and avoid SYSTEM-F-HEADERFULL errors, HP strongly recommends that you set this value to be approximately the number of files that you anticipate having on your disk. However, grossly overestimating this value will result in wasted disk space.

1. $ INITIALIZE/HEADERS=100000 DUA3:

   This example shows how many entries to allocate in the index files for a large disk (a small disk might allocate 2000 entries).

2. $ INITIALIZE/MAXIMUM_FILES=20000 DUA3:

   This example shows how to specify the characteristics of a small disk. Note that each directory and each extension header of a multiheader file counts as a file against this maximum value.

3. $ INITIALIZE/WINDOWS=10 DUA3:

   This example shows how to cite a large number of pointers for a large disk of 500 MB.

Initializing a New Volume with ODS-5 Format  

You can initialize a new volume as an ODS-5 volume by entering the INITIALIZE command using the following format. Note that once you initialize the volume, the current contents of the volume are lost.

$ INITIALIZE /STRUCTURE_LEVEL=5 device-name volume-label

$ INITIALIZE /STRUCTURE_LEVEL=5 DKA300: DISK1
$ MOUNT DKA300: DISK1 /SYSTEM
%MOUNT-I-MOUNTED, DISK1 mounted on _STAR$DKA300:

To verify that the volume has been initialized as an ODS-5 volume, you can enter a SHOW DEVICE/FULL command; the system displays messages similar to the following:

$ SHOW DEVICE DKA200:/FULL
 
  Disk $10$DKA200:, device type RZ74, is online, allocated, deallocate
  on dismount, mounted, file-oriented device, shareable.
 
    Error count                    0    Operations completed 155
    .
    .
    .
  Volume Status:  ODS-5, subject to mount verification, file high-water
  marking, write-back caching enabled.

$ WRITE SYS$OUTPUT F$GETDVI ("DKA200:","ACPTYPE")
F11V2

If you plan to add the new volume to a volume set, the structure level of the new volume must match that of the volume set. If it does not, the Mount utility displays the following error message: Structure level on device ... is inconsistent with volume set.

Assisting Users in Accessing and Initializing Volumes  

Initializing volumes for users might be necessary in some circumstances:

• If the volume previously contained data, the protection code might prevent users from accessing and initializing the volume.



• If the first file section on the volume has not reached its expiration date, users might not be able to initialize a tape volume.



• If the volume is owned by anyone except [0,0], the user must have VOLPRO privilege to override volume protection. If users do not have VOLPRO privilege, they must ask the previous owner of the volume or you, as system manager, to initialize it for them.



• If a tape is blank, the user must have VOLPRO and OPER privileges to access and initialize it.

Allocating and Deallocating Drives

Protecting Volumes