HP OpenVMS Systems Documentation

Input or Output Save-Set Qualifier

As an input save-set qualifier, /CRC causes the software cyclic redundancy check (CRC) encoded in the save set's data blocks to be checked (/CRC) or ignored (/NOCRC). If you ignore the CRC encoding, you reduce processing time at the risk of increasing data error.

As an output save-set qualifier, /CRC specifies that software CRC checking code is to be computed and stored in the data blocks of the output save set. To disable CRC checking, use the /NOCRC qualifier.

Input Save-Set Qualifier

See a separate description of /CRC as an output save-set qualifier.

Specifies that the software cyclic redundancy check (CRC) is to be performed.

Format

input-save-set-spec/[NO]CRC output-specifier

Description

The default is /CRC. To disable CRC checking, specify /NOCRC; note that use of /NOCRC reduces processing time but increases the risk of data loss.

Example

$ BACKUP MTA2:988SAVE.BCK/NOCRC []
      

This command restores the save set 988SAVE.BCK to the current default directory, indicated by ([]); the input save-set qualifier /NOCRC disables CRC.

Output Save-Set Qualifier

See a separate description of /CRC as an input save-set qualifier.

Specifies whether the software cyclic redundancy check (CRC) is to be computed and stored in the data blocks of the output save set.

Format

input-specifier output-save-set-spec/[NO]CRC

Description

The default is /CRC. To disable checking, use /NOCRC; note that use of /NOCRC reduces processing time but increases the risk of data loss.

Example

$ BACKUP/RECORD []/SINCE=BACKUP MTA2:988SAVE.BCK/NOCRC
      

This command saves all files in the current default directory that have been created or modified since the last BACKUP/RECORD operation to the save set 988SAVE.BCK; the output save-set qualifier /NOCRC disables cyclic redundancy checking.

Input File-Selection Qualifier

Selects files according to the value of the creation date field in each file header record.

Format

input-specifier/BEFORE=time/CREATED output-specifier

input-specifier/SINCE=time/CREATED output-specifier

Description

You must use either the /BEFORE qualifier or the /SINCE qualifier with /CREATED. The date and time you specify with /BEFORE or /SINCE determine which files should be processed.

You cannot use /CREATED with the /BACKUP, /MODIFIED, or /EXPIRED qualifiers.

Example

$ BACKUP *.SDML/SINCE=YESTERDAY/CREATED DLA2:[SAVEDIR]/SAVE_SET
      

The command in this example saves all files with a file type of .SDML created since yesterday (24 hours before midnight last night).

Command Qualifier

Creates and restores compressed save sets. You can specify the /DATA_FORMAT qualifier anywhere on the BACKUP command line.

Format

/DATA_FORMAT=COMPRESS[=algorithm]

Description

For compression support specify /DATA_FORMAT=COMPRESS with the algorithm name. The compression algorithm should be mentioned with the qualifier, as of now only one algorithm is supported (that is DEFLATE) and used as default.

Note The BACKUP compression is supported only for save set file operation on disk and sequential devices.

Examples

$ BACKUP/DATA_FORMAT=COMPRESS SYS$SYSTEM:*.EXE DKA0:[000000]SAVESET.BCK/SAVE
      

This command saves the system executable file (SYS$SYSTEM:*.EXE) to a save set named SAVESET.BCK on to the disk DKA0. Since, no compression algorithm is specified the default DEFLATE compression algorithm is used to compress the data.

$ BACKUP/DATA_FORMAT=COMPRESS=DEFLATE /IMAGE/RECORD DKA0: $2$MGA0:SUT746.BCK/SAVE
      

This command creates the image backup of the disk DKA0 in the save set named SUT746.BCK on the magnetic tape labeled SUT746. Since the qualifier /DATA_FORMAT=COMPRESS is mentioned the created save set is compressed with this algorithm.

$ BACKUP/DATA_FORMAT=COMPRESS SAVESET.BCK/SAVE DKA100:[000000...]
      

In this command, the save set SAVESET.BCK is restored to the directory tree DKA0:[000000]. /DATA_FORMAT=COMPRESS qualifier is specified here, in case if the save set is an uncompressed save set the qualifier is ignored and restore operation is continued.

On the other hand, if save set is compressed and /DATA_FORMAT= COMPRESS is not specified during restore, BACKUP identifies the save set as a compressed save set and restores it successfully.

Command Qualifier

Specifies that a BACKUP save or copy operation is to delete the selected input files from the input volume after all files have been successfully processed.

Format

/DELETE file-spec save-set-spec

Description

The /DELETE qualifier is valid only when used in a BACKUP save or copy operation. You must have sufficient privilege to delete files; if you do not, files protected against deletion are not deleted. If you use the command qualifier /VERIFY with /DELETE, files that fail verification are not deleted.

You cannot use /DELETE with the /PHYSICAL, /RECORD or /COMPARE command qualifiers.

Examples

$ BACKUP/DELETE BOP.DAT MTA0:BOP.BCK/LABEL=DANCE
      

In this example, the file BOP.DAT will be deleted after the save set BOP.BCK is successfully created on MTA0.

$ BACKUP/VERIFY/DELETE RAY.DAT,JOE.DAT,ELLA.DAT MTA0:OSCAR.BCK/LABEL=FRIEND
      

The BACKUP command deletes the selected list of files in this example after saving them to OSCAR.BCK on MTA0 and comparing the output save set with the input files. If BACKUP detects a difference between the contents of the output save set and the input file, the input file is not deleted.

Output Save-Set Qualifier

Specifies the recording density of the output magnetic tape. Use a value that is supported by the magnetic tape drive.

If you do not specify the /DENSITY qualifier, the default density is the current density of the magnetic tape drive. You must specify the output save-set qualifier /REWIND with /DENSITY.

Format

input-specifier output-save-set-spec/DENSITY=keyword

The following table shows shows the densities that are supported for tapes.

Note that tape density keywords cannot be abbreviated.

Description

The value that you specify must be supported by your magnetic tape hardware. If you omit this qualifier, the default density is the current density on the output tape drive.

The /DENSITY qualifier is incompatible with the output save-set qualifier /NOREWIND. You must specify the output save-set qualifier /REWIND to initialize the magnetic tape when using the /DENSITY qualifier. When you specify /DENSITY/REWIND, BACKUP rewinds the tape to the beginning-of-tape. Then BACKUP initializes the tape with the new density, removing access to all data that previously resided on the tape.

Example

$ BACKUP *.PAS MTA2:SAVEPAS.BCK/DENSITY=1600/REWIND/LABEL=PASCAL
      

The magnetic tape on drive MTA2: is initialized. All files with a file type of .PAS in the current default directory are saved to the save set SAVEPAS.BCK. The /DENSITY qualifier sets the recording density to 1600 bits/in.

Command Qualifier

Creates and restores encrypted save sets. Specify the /ENCRYPT qualifier anywhere on the BACKUP command line.

Note Standalone BACKUP, which is a version of the BACKUP utility that runs without the support of the OpenVMS operating system, does not support the /ENCRYPT qualifier.

Format

/ENCRYPT=([key] [,ALGORITHM=algorithm])

Description

Optionally, you can specify either a key name or a key value, but not both. If you have already defined a key value using the DCL command ENCRYPT/CREATE_KEY, you can specify /ENCRYPT=NAME=key-name to identify the key name that was created and stored in the key storage table.

To define a key value interactively, specify /ENCRYPT=VALUE=key-value,
where key-value is one of the following:

• 1 to 243 alphanumeric characters enclosed in quotation marks (""). Dollar signs ($) and underscores (_) are valid characters. The key is not case sensitive.
• A hexadecimal constant using the digits 0 to 9 and A to F.

Note For additional security, specify the /ENCRYPT qualifier with no parameters and press Return. The command prompts you for a key value. When you enter a value, the software does not echo what you type and, for verification, prompts you to retype the value.

ALGORITHM Keyword

Optionally, you can use ALGORITHM=algorithm to specify DES or AES algorithms:

• Data encryption standard (DES)
  Use DES to encrypt the initialization vector and the key you supply. Possible values for algorithm are as follows:
  • DESCBC (default) --- Cipher block chaining
  • DESECB --- Electronic code book
  • DESCFB --- Cipher feedback
• Advanced encryption standard (AES)
  Use an AES algorithm to encrypt both the data and the user-provided key using the AES algorithm. Possible values for algorithm are as follows:
  • AESCBC --- Cipher block chaining
  • AESECB --- Electronic code book
  • AESCFB --- Cipher feedback
  • AESOFB --- Output feedback
  
  You can also specify one of the following three lengths for AES:

  128
  192
  256

  
  When you use an AES value, BACKUP places the result of the encryption operation in the save set as a BACKUP attribute subrecord of the BACKUP summary record. At the time of a save set restore or listing operation, BACKUP uses the key you supplied to get to the encrypted key to decrypt the data key and the initialization vector value.

Using /ENCRYPT and /SAVE_SET Qualifiers

The BACKUP command qualifier /SAVE_SET is both an input save set qualifier and an output save set qualifier, as follows:

• When you specify the /SAVE_SET and /ENCYRPT qualifiers with an output save set specification, BACKUP writes file data (including file names and attributes) in an encrypted form into the save set.
• When you specify /SAVE_SET with an input save set specification, BACKUP uses the decryption key specified to access the file name, attributes, and data from the save set records. The ENCRYPT option decrypts the data files after BACKUP reads the data files from the save set media and processes them according to the remaining qualifiers of the BACKUP command.

Restoring Files

When you encrypt a save set, BACKUP does not store the encryption key in the save set header. Consequently, to decrypt an encrypted save set, specify /ENCRYPT in the restore operation so that BACKUP searches for the data encryption control record.

If you restore an unencrypted save set and mistakenly specify /ENCRYPT, BACKUP ignores the incorrect qualifier. If you try to restore an encrypted save set without the /ENCRYPT qualifier or with a key name, the system displays the following error message:

%BACKUP-F-ENCSAVSET, save set is encrypted, /ENCRYPT must be specified.

BACKUP tries to decrypt an encrypted save set by:

1. Decrypting the encryption data saved in an attribute subrecord.
2. Comparing a 32-bit checksum of the decrypted data key with the stored value.
3. If there is a match, BACKUP assumes the data key is valid and restores the save set.
4. If BACKUP finds a mismatch, which is likely if the data key or algorithm you specified in the BACKUP command is incorrect, the utility displays the following error message:

%BACKUP-F-ENCKEYMAT, the supplied decryption key does not yield a readable save set

Examples

$ ENCRYPT/CREATE_KEY my_key "This is my private encryption key"/AES/LOG
%ENCRYPT-S-KEYDEF, key defined for key name = MY_KEY
$ BACKUP *.COM COMS.BCK/SAVE/ENCRYPT=(name=my_key,alg=AES_/LOG)
      

This example creates an encrypted save set.

$ BACKUP *.COM COMS.BCK/SAVE/ENCRY=ALG=AES
Enter key value:
Verification:
$
      

In this example, the BACKUP command line does not contain a key name or key value; therefore, BACKUP prompts for an encryption key.

$ BACKUP DKA100: DKA100.BCK/SAV/IMA/ENCRY=(VALUE="THIS IS MY 
ENCRYPTION KEY")
      

In this example, the image BACKUP of DKA100 is encrypted in a save set with a key value that uses the default DESCBC algorithm.

$ BACKUP DKA100: DKA100.BCK/SAV/IMA/ENCRY=(VALUE="THIS IS MY 
ENCRYPTION KEY",ALGO=AESCFB192)
      

In this example, the image BACKUP of DKA100 is encrypted in a saveset with a key value that uses the AESCFB algorithm with a 192-bit encryption key.

Output Save-Set Qualifier

Depending on the other qualifiers you specify on the command line, the /EXACT_ORDER qualifier allows you to perform the following actions:

• Specify the exact order of tape volume labels that you want to use in a BACKUP operation.
• Preserve the existing volume label on a tape.
• Prevent previous volumes of a multivolume save operation from being overwritten.

Format

input-specifier output-save-set-spec/EXACT_ORDER

Description

The /EXACT_ORDER qualifier allows you to perform the following actions:

• Specify the exact order of tape volume labels that you want to use in a BACKUP operation. You must use the /LABEL=(label1,label2,...) qualifier to specify the order of the labels. BACKUP continues the operation as long as the label of the tape in the drive matches the corresponding label on the command line. If you do not specify enough labels on the command line to complete the operation, BACKUP prompts you to enter a label for the tape in the drive.
• Preserve the existing volume label on a tape. If you do not use the /LABEL qualifier on the command line and the tape has an ANSI label, BACKUP uses the existing label.
• Prevent previous volumes of a multivolume save operation from being overwritten. BACKUP keeps track of the volume labels you have already used in the operation. If you accidently mount one of the previous volumes, BACKUP displays the following error message:

  %BACKUP-W-MOUNTERR, volume 1 on MKB100: was not mounted because its label does not match the one requested Volume with label TAPE1 was already used in this save operation. Specify option (QUIT or NEW tape) BACKUP>

Note the following restrictions when you use the /EXACT_ORDER output qualifier:

• If you use the /EXACT_ORDER qualifier, you cannot specify a label longer than six characters on the command line. If you specify a label longer than six characters, BACKUP displays the following error message:

  %BACKUP-F-INVQUAVAL, value 'label_name' invalid for /LABEL qualifier

• You cannot use the /IGNORE=LABEL_PROCESSING qualifier with the /EXACT_ORDER qualifier.
• If you use the /LABEL qualifier with the /EXACT_ORDER qualifier, you cannot specify duplicate labels.

The default is /NOEXACT_ORDER.

Examples

$ BACKUP/IMAGE/RECORD/VERIFY/NOASSIST
_From: DKA100:
_To: MKB100:MAR11.SAV/LABEL=(TAPE1,TAPE2,TAPE3)/EXACT_ORDER
      

This example uses the /EXACT_ORDER qualifier to specify the exact order of labels for the BACKUP operation. Note that if you specify the /ASSIST qualifier, BACKUP would display messages on the operator terminal. BACKUP performs the following actions:

1. Compares the volume label of the tape in MKB100: with the first label that you specified on the command line (TAPE1). If the labels match exactly, BACKUP begins the save operation. If the labels do not match or if the tape does not have an ANSI label, BACKUP displays the following message:

   %BACKUP-W-MOUNTERR, volume 1 on MKB100: was not mounted because its label does not match the one requested %BACKUP-W-EXLABEER, volume label processing failed because volume TAPE4 is out of order, Volume label TAPE1 was expected. Specify option (QUIT, NEW tape, OVERWRITE tape, USE loaded tape) BACKUP> OVERWRITE

   
   Depending on the option you specify, you can quit the backup operation (QUIT), dismount the old tape and mount a new one (NEW), overwrite the label and the data on the tape (OVERWRITE), or write the data to the tape using the loaded tape's label (USE).
2. When the operation fills the first tape, it displays the following message:

   %BACKUP-I-RESUME, resuming operation on volume 2 %BACKUP-I-READYWRITE, mount volume TAPE2 on MKB100: for writing. Respond with YES when ready:

3. When you load the second tape and enter YES, BACKUP compares the label of the second tape with the second label you specified on the command line (TAPE2) just as it did in step 1a.
4. Assuming the volume labels match, BACKUP continues processing until it completes the operation or runs out of volume labels. If you do not specify enough labels on the command line to complete the operation, BACKUP prompts you to enter a label for the tape in the drive as follows:

   %BACKUP-W-MOUNTERR, volume 4 on MKB100: was not mounted because the label was not specified Specify EXACT_ORDER label (up to 6 characters) BACKUP>

   
   BACKUP then compares the label on the tape with label you specify as described previously.

$ BACKUP/IMAGE/RECORD/VERIFY/NOASSIST
_From: DKA100:[TEST]
_To: MKB100:MAR11.SAV/EXACT_ORDER
      

Because this example does not use the /LABEL qualifier, BACKUP uses the existing label on the tape. If the tape does not have an ANSI label, and it is the first tape in the operation, BACKUP displays the following error message:

%BACKUP-F-NOTANSI, tape is not valid ANSI format

If the tape does not have an ANSI label, and is not the first tape in the operation, BACKUP displays the following error message prompting you to specify a label:

%BACKUP-W-MOUNTERR, volume 2 on MKB100: was not mounted because the label was not specified Specify EXACT_ORDER label (up to 6 characters) BACKUP>

BACKUP checks to make sure you specify a valid label. If the label is not valid (for example, longer than six characters), BACKUP displays an error message. In previous versions of the OpenVMS operating system, BACKUP truncated long volume labels.