Document revision date: 30 March 2001

## OpenVMS System Manager's Manual

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## 11.6 Understanding BACKUP File Formats

On VAX systems, BACKUP saves files and directories from Files--11 Structure Level 1 and 2 disks to disks or magnetic tapes. If necessary, you can use BACKUP to restore the saved files and directories to Files--11 Structure Level 1 and 2 disks.

If a VAX system performs image backup of an Alpha system disk, a restore operation causes the Alpha system to reboot successfully.

On Alpha systems, BACKUP can save files and directories from Files--11 Structure Level 2 or 5 disks to either disks or magnetic tapes. If necessary, you can use BACKUP to restore the saved files and directories to Files--11 Structure Level 2 or 5 disks.

Note The OpenVMS Alpha operating system does not support the Files--11 Structure Level 1 format.

You cannot back up files on ISO 9660-formatted media, but you can restore save sets stored on ISO 9660-formatted media.

For more information about the Files--11 disk structure, see Section 9.1.1.2. For more information about ISO 9660 devices, see Section 8.2.2.

## 11.7 Setting Process Quotas for Efficient Backups

You can optimize the efficiency of backups on your system by properly setting the process quotas for the process from which backups will be made (the process from which you enter the BACKUP command or submit your backup command procedure). This is especially important if you are using a streaming tape drive.

How to Perform This Task

To set process quotas for efficient backups, perform the following actions:

1. Determine which account you want to use for backups. You can use an existing account, or create one solely for backups. For information about creating accounts, see Section 7.6.
2. Use the Authorize utility (AUTHORIZE) to determine the current quota values for the account you will use for backups. For example, if you are using the SYSTEM account for backups, enter the following commands:

       $ SET DEFAULT SYS$SYSTEM
       $ RUN AUTHORIZE
       UAF> SHOW SYSTEM

3. Using the System Management utility (SYSMAN), determine the value of the system parameters WSMAX and CHANNELCNT, as follows:

       $ RUN SYS$SYSTEM:SYSMAN
       SYSMAN> PARAMETERS SHOW WSMAX
       %SYSMAN-I-USEACTNOD, a USE ACTIVE has been defaulted on node DIEM
       Node DIEM:   Parameters in use: ACTIVE
       Parameter Name          Current   Default   Minimum   Maximum Unit  Dynamic
       --------------          -------   -------   -------   ------- ----  -------
       WSMAX                      2600      1024        60    100000 Pages
       SYSMAN> PARAMETERS SHOW CHANNELCNT
       Parameter Name          Current   Default   Minimum   Maximum Unit  Dynamic
       --------------          -------   -------   -------   ------- ----  -------
       CHANNELCNT                 127       127        21     2047 Channels

       SYSMAN> EXIT
       $

   In this case, the values for WSMAX and CHANNELCNT, as shown in the column marked Current, are 2600 and 127, respectively. Use these values to help set the correct values for the process quotas.
4. Use AUTHORIZE to compare the values for the process quotas to the recommended values for efficient backups, as shown in Table 11-4.

   Table 11-4 Recommended Process Quotas for Efficient Backups
   Process Quota | Recommended Setting
   --- | ---
   WSQUOTA | Equal to system parameter WSMAX
   WSEXTENT | Equal to WSQUOTA quota
   PGFLQUOTA | Equal to or greater than WSEXTENT quota
   FILLM | Less than system parameter CHANNELCNT
   DIOLM | Either 4096 or three times the value of FILLM quota, whichever is greater
   ASTLM | Either 4096, at least 100 greater than DIOLM quota, or three times the value of FILLM quota, whichever is greater
   BIOLM | Equal to FILLM
   BYTLM | Equal to or greater than the following value: (256*FILLM)+(6*DIOLM)
   ENQLM | Greater than FILLM quota

5. If necessary, change process quotas using the AUTHORIZE command MODIFY. If you change process quotas, you must log out and log in again for the changes to take effect. For information about changing these process quotas, see Section 7.7.2.
   Table 11-5 lists a set of process quota values that are appropriate for many configurations. If your disks are highly fragmented or if your backups will be performed during periods of heavy system use, you should reduce the values shown for WSQUOTA and FILLM.

   Table 11-5 Sample Process Quotas for Efficient Backups
   Process Quota | Suggested Value
   --- | ---
   WSQUOTA | 16384
   WSEXTENT | Greater than or equal to WSQUOTA
   PGFLQUOTA | 32768
   FILLM | 128
   DIOLM | 4096
   ASTLM | 4096
   BIOLM | 128
   BYTLM | 65536
   ENQLM | 256

Example

The following steps show the commands that you would use to run the Authorize utility and set process quotas for the SYSTEM account (if you plan to run backups from a different account, determine the process quotas for that account):

1. Determine the current quota values:

       $ SET DEFAULT SYS$SYSTEM
       $ RUN AUTHORIZE
       UAF> SHOW SYSTEM
       Username: SYSTEM                           Owner:  SYSTEM MANAGER
       Account:  SYSTEM                           UIC:    [1,4] ([SYSTEM])
       CLI:      DCL                              Tables: DCLTABLES
       Default:  SYS$SYSROOT:[SYSMGR]
                                        .
                                        .
                                        .
       Maxjobs:         0  Fillm:        40  Bytlm:        32768
       Maxacctjobs:     0  Shrfillm:      0  Pbytlm:           0
       Maxdetach:       0  BIOlm:        18  JTquota:       1024
       Prclm:          10  DIOlm:        18  WSdef:          256
       Prio:            4  ASTlm:        24  WSquo:          512
       Queprio:         0  TQElm:        20  WSextent:      2048
       CPU:        (none)  Enqlm:       200  Pgflquo:      20480
                                        .
                                        .
                                        .
       UAF> EXIT
       %UAF-I-NOMODS, no modifications made to system authorization file
       %UAF-I-NAFNOMODS, no modifications made to network authorization file
       %UAF-I-RDBNOMODS, no modifications made to rights database
       $

   In this example, SYSTEM has the following quotas:

   WSQUOTA | 512
   WSEXTENT | 2048
   PGFLQUOTA | 20480
   FILLM | 40
   DIOLM | 18
   ASTLM | 24
   BIOLM | 18
   BYTLM | 32768
   ENQLM | 200

2. Using the System Management utility (SYSMAN), determine the value of the system parameters WSMAX and CHANNELCNT, as follows:

       $ RUN SYS$SYSTEM:SYSMAN
       SYSMAN> PARAMETERS SHOW WSMAX
       %SYSMAN-I-USEACTNOD, a USE ACTIVE has been defaulted on node DIEM
       Node DIEM:   Parameters in use: ACTIVE
       Parameter Name          Current   Default   Minimum   Maximum Unit  Dynamic
       --------------          -------   -------   -------   ------- ----  -------
       WSMAX                      2600      1024        60    100000 Pages
       SYSMAN> PARAMETERS SHOW CHANNELCNT
       Parameter Name          Current   Default   Minimum   Maximum Unit  Dynamic
       --------------          -------   -------   -------   ------- ----  -------
       CHANNELCNT                 127       127        21     2047 Channels

       SYSMAN> EXIT
       $

   In this case, the values for WSMAX and CHANNELCNT, as shown in the column marked Current, are 2600 and 127, respectively.
3. Compare the values for SYSTEM to the values in Table 11-4, and set the appropriate values:

       $ SET DEFAULT SYS$SYSTEM
       $ RUN AUTHORIZE
       UAF> MODIFY SYSTEM/WSQUOTA=2600
       UAF> MODIFY SYSTEM/WSEXTENT=2600
       UAF> MODIFY SYSTEM/DIOLM=4096
       UAF> MODIFY SYSTEM/ASTLM=4096
       UAF> MODIFY SYSTEM/BIOLM=40
       UAF> MODIFY SYSTEM/BYTLM=34816
       UAF> EXIT

4. Log out and then log in again so that these process quotas take effect.

## 11.8 Using Disks and Tapes

During the course of your backup operations, you will use both disk and tape volumes. The steps you normally perform before using a volume in a backup operation are:

1. Determine the device name.
2. Allocate the device.
3. Initialize the volume (optional).
4. Mount the device (for disks only; BACKUP mounts tapes automatically).

These tasks are described in Chapter 9. This chapter describes specifically how these tasks relate to BACKUP. Note that all disk operations in this chapter also apply to diskettes.

### 11.8.1 Understanding Volume Initialization

Initializing a volume completes the following actions:

- Formats it in the OpenVMS Files--11 format
- Assigns it an ANSI label
- Removes links to any existing files (effectively erasing them)
- Writes a tape expiration date and volume protection data to the volume header record of the tape

Caution Initializing a volume removes links to existing files on the volume, effectively erasing the files. Do not initialize a volume that contains data you want to keep.

#### 11.8.1.1 When to Initialize Volumes

You must initialize a volume for use with BACKUP if any of the following conditions exist:

- The volume is new and has not been formatted in the Files--11 format.
- You want to remove access to data stored on the volume.
- You want to change the volume label, expiration date, or volume protection data.
- The volume contains a non-ANSI or non-ISO label.

Table 11-6 show the three ways to initialize a volume.

Table 11-6 Methods of Volume Initialization
Method | For More Information
--- | ---
Before a backup operation with the DCL command INITIALIZE | Section 9.3
On the BACKUP command line with the /REWIND qualifier (for tapes only) | Section 11.8.1.2
On the BACKUP command line with the /INITIALIZE qualifier (for disks only) | Section 11.8.1.3

#### 11.8.1.2 Initializing Tapes

Instead of using the INITIALIZE command and then performing a backup operation, you can initialize a tape and perform a backup operation by entering one BACKUP command.

How to Perform This Task

To initialize a tape volume on the BACKUP command line, add the /REWIND and /LABEL qualifiers to the output specifier. The /REWIND qualifier rewinds and initializes the volume. The /LABEL qualifier allows you to specify the volume label.

Magnetic tape volume labels can contain a maximum of six characters. You can use any ANSI "a" character in a magnetic tape volume label. The ANSI "a" characters include numbers, uppercase letters, and any of the following nonalphanumeric characters:

`! " % ' ( ) * + , _ . / : ; < = > ?`

If you use any nonalphanumeric characters, you must enclose the volume label with quotation marks.

Label your magnetic tapes according to the data contained on the tapes. The following table presents some suggestions for labeling tapes:

Label | Type of Backup | Expiration Date
--- | --- | ---
DLY101 | Daily, group 1, volume number 1 | Expires in 7 days
DLY102 | Daily, group 1, volume number 2 | Expires in 7 days
WKY101 | Weekly, group 1, volume number 1 | Expires in 4 weeks
WKY201 | Weekly, group 2, volume number 1 | Expires in 4 weeks
MTH101 | Monthly, group 1, volume number 1 | Expires in 12 months
YRY101 | Yearly, group 1, volume number 1 | Expires in 5 years

Note that:

- If the tape volume has already been initialized with a label that is different from the label you specify on the BACKUP command line, BACKUP displays an error message about the label mismatch. For more information, see Section 11.12.
- If the tape is not expired, BACKUP displays the following error message:

      %INIT-F-FILNOTEXP, file is not expired

  If you have either VOLPRO privilege or write access to the volume, or you are the owner of the volume, you can use the DCL command INITIALIZE/OVERRIDE=EXPIRATION to initialize the magnetic tape.
  You can also reenter the BACKUP command line using the /IGNORE=LABEL_PROCESSING qualifier (refer to the OpenVMS System Management Utilities Reference Manual).
- If the volume was previously initialized with the output save-set qualifiers /REWIND and /PROTECTION, you must either own the volume (your UIC matches the owner UIC of the volume) or have VOLPRO privilege.

Example

    $ BACKUP [ACCOUNTS.JUNE] MUA0:JUNE.BCK/REWIND/LABEL=MTH101

#### 11.8.1.3 Initializing Disks

Instead of using the INITIALIZE command and then performing a backup operation, you can initialize a disk and perform a backup operation by entering one BACKUP command.

How to Perform This Task

The two ways to initialize a disk during a backup operation are:

- When you perform an image copy to disk, BACKUP automatically initializes the output disk, effectively erasing any existing files and volume-initialization data on the disk. To preserve volume-initialization data on the output disk, use the /NOINITIALIZE qualifier.
- When you create a sequential disk save set, BACKUP does not initialize the output volume (by default). You can, however, instruct BACKUP to initialize the output volume using the /INITIALIZE qualifier.

Examples

1. The following command shows how to initialize a disk on the BACKUP command line:

       $ BACKUP/IMAGE DUA1: DUA2:

   This command initializes DUA2: using the volume-initialization data from DUA1. BACKUP then copies the contents of DUA1: to DUA2:, effectively erasing any existing files on DUA2. Note that the files on DUA2: are stored contiguously, eliminating disk fragmentation.
2. The following command shows how to preserve volume-initialization data on the output disk during an image copy:

       $ BACKUP/IMAGE DUA1: DUA2:/NOINITIALIZE

   This command causes BACKUP to initialize DUA2:, preserving the initialization data on that volume. BACKUP then copies the contents of DUA1: to DUA2:, effectively erasing any existing files on DUA2.
3. These commands cause BACKUP to initialize DJA2:, effectively erasing any existing files:

       $ MOUNT/FOREIGN DJA2:
       %MOUNT-I-MOUNTED, USER1 mounted on _DJA2:
       $ BACKUP/IMAGE DUA1: DJA2:DAILY.SAV/INITIALIZE

   BACKUP then creates an image backup of DUA1: in the sequential disk save set DUA2:[000000]DAILY.SAV. If the save set exceeds the available disk space, BACKUP prompts for another volume. BACKUP initializes the new volume and extends the save set in the master file directory ([000000]) of the new volume. (For more information about save sets, see Section 11.5. For more information about the /INITIALIZE qualifier, refer to the OpenVMS System Management Utilities Reference Manual.)

### 11.8.2 Mounting a Volume

Mounting a volume makes it available to the system. BACKUP automatically mounts tapes when you use them for a backup operation. Most disks on your system are mounted at system startup. This section describes how to explicitly mount volumes.

If you are planning to write a save set to a disk, decide whether the save set will be written in standard Files--11 format or in sequential-disk format:

- If the save set will be written in standard Files--11 format, the target disk must be mounted as a Files--11 disk.
- If a save set will be written in sequential-disk format (for example, if the save set occupies more than one disk), the target disk must be mounted as a foreign device by specifying the command qualifier /FOREIGN to the DCL command MOUNT.

How to Perform This Task

1. Enter the SHOW DEVICES command in the following format to check whether the device is already mounted:

   `SHOW DEVICES device-name`

2. Enter the MOUNT command in the following format:

   `MOUNT [/FOREIGN] device-name [volume-label] [logical-name]`

   where:

   device-name | is the name of the drive that holds the volume you want to mount.
   volume-label | is the alphanumeric identification you assigned to the volume with the INITIALIZE command. For disk volumes, labels can have a maximum of 12 characters; for magnetic tape volumes, labels can have a maximum of 6 characters. You do not need to add this parameter if you are mounting the volume with the /FOREIGN qualifier.
   logical-name | is an optional 1- to 255-character alphanumeric specification that you want to associate with the volume.

Example

    $ SHOW DEVICE MU
    Device                  Device           Error    Volume         Free  Trans Mnt
     Name                   Status           Count     Label        Blocks Count Cnt
    DAD$MUA6:               Online               0
    MOM$MUA6:               Online               0
    FRED$MUA6:              Online               0
    $ MOUNT/FOREIGN FRED$MUA6: TEST DRIVE1
    %MOUNT-I-MOUNTED, TEST mounted on _FRED$MUA6:

This command mounts the tape in FRED$MUA6: and assigns it the logical name DRIVE1.

### 11.8.3 Dismounting a Volume

BACKUP does not dismount the last volume of a backup operation (unless you use the /RELEASE_TAPE qualifier). When you finish using a volume, you should dismount it.

How to Perform This Task

Enter the DISMOUNT command in the following format:

`DISMOUNT device-name`

Example

The following command dismounts a tape in drive MUB6:

    $ DISMOUNT MUB6:

This command dismounts and unloads the tape in MUB6. After you dismount and unload the volume, you can remove it from the drive. To dismount the tape but not unload it, enter the following command:

    $ DISMOUNT/NOUNLOAD MUB6:

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