You can make backup copies in the following units. The database copy utility provides an option to specify these backup units. The table below shows the backup units.

Table 18-1 Backup units

Backup unit	Description	Option
By the system	Backs up all RDAREAs in the system (including master directory RDAREAs), except the user RDAREAs. List RDAREAs and temporary table RDAREAs are not subject to backup processing.	-a
By the unit#	Backs up all RDAREAs in a specified unit.	-u
By the server#	Backs up all RDAREAs in a specified server.	-s
By the RDAREA	Backs up specified RDAREAs. A group of RDAREAs can be backed up by specifying its RDAREA names as a regular expression.	-r

#: This is applicable to a HiRDB parallel server configuration only, and is not applicable to a HiRDB single server configuration.

The database copy utility's -M option lets you select a backup acquisition mode. The table below shows the available backup acquisition modes.

Table 18-2 Backup acquisition modes

Backup acquisition mode (value of -M option)	Description	Database recovery method
x	This mode does not allow an RDAREA under backup processing to be referenced or updated. Use the pdhold command to place the RDAREA subject to backup processing in the shutdown and closed status.	Only the backup copy is needed to restore the database to the status existing when the backup copy was made.
r	This mode allows an RDAREA under backup processing to be referenced but does not allow it to be updated.
s	This mode allows an RDAREA to be referenced or updated while it is being backed up. If LVM (logical volume manager) is used for the database, the RDAREA to be backed up must be placed in backup hold status. This option is applicable when the RDAREA to be backed up is created in a character special file.	The backup copy and the system log obtained during backup processing# are needed to restore the database.

#: The database copy utility process results listing contains the name and generation number of the system log file required for restoring the RDAREA. For details about the database copy utility process results listing, see 18.6 Database copy utility process results listing.

Note

To back up all RDAREAs during HiRDB operation (in units of systems), specify r or s for the backup acquisition mode (-M option). You cannot specify x for the following reason: to specify x, you need to place all RDAREAs subject to backup processing in the shutdown and closed status using the pdhold command. However, the master directory RDAREA cannot be placed in the shutdown and closed status. Therefore, you cannot specify x in the -M option to back up all RDAREAs during HiRDB operation.

We recommend that you back up data periodically as well as at the times listed below. If backups are not made at these times, a database cannot be restored to its most recent synchronization point in the event of an error.

• Before and after executing a UAP or utility in the no-log mode
• After executing a UAP or utility in the pre-update log acquisition mode
• After executing the database structure modification utility on RDAREAs
  If you are moving RDAREAs, also back up data beforehand.
  
• After performing recovery processing using system logs
• Before performing recovery processing using unload log files only
• Before and after upgrading HiRDB
• After registering plug-ins (after executing the pdplgrgst command)
• After discontinuing use of plug-ins (after deleting the pdplugin operand)
• After placing RDAREAs in memory and after synchronizing in-memory data buffer and in-memory RDAREAs

Backing up data at the following times might reduce the time required for recovery in the event of an error:

• After performing processes that require system RDAREAs to be backed up
  The processes that require system RDAREAs to be backed up are those that require that the master directory RDAREA, the data directory RDAREA, or data dictionary RDAREAs be backed up, as described in RDAREAs to be backed up together in the HiRDB Version 9 System Operation Guide.
  
• After updating a large amount of table data

When backing up a specific RDAREA, you also need to back up those RDAREAs that are updated by the RDAREA backup processing (such as data dictionary RDAREAs). For details about the RDAREAs that need to be backed up at the same time, see the HiRDB Version 9 System Operation Guide.

You can create a backup file in any server machine where HiRDB is running. There is no need to create a backup file in the same server machine that contains the corresponding RDAREA. You might want to create backup files in the server machine that has a CMT device.

To create a backup file in a character special file, define that character special file as a HiRDB file system area for the utility. To do this, specify UTL in the -k option of the pdfmkfs command.

If you are running the system without unloading the system log, you need to obtain a log point information file when making a backup copy. To obtain a log point information file, specify the -z option with the database copy utility.

For details about how to operate without unloading the system log, see the HiRDB Version 9 System Operation Guide.

The differential backup facility backs up only the information that has changed since the previous backup, thereby reducing the backup processing time. Consider using the differential backup facility when the database is large and the amount of data that has been updated is small.

To use the differential backup facility, specify the -g, -d, -K, -o, and -L options.

For details about using the differential backup facility, see the HiRDB Version 9 System Operation Guide.

Note that the differential backup facility does not support in-memory RDAREAs.

When you have backed up in-memory RDAREAs, the method for restoring those RDAREAs might differ from the normal method. For details about how to back up and restore in-memory RDAREAs, see the manual HiRDB Version 9 Batch Job Accelerator.

The inner replica facility is used when there is not enough time to make a backup of the database, such as when online applications are running 24 hours a day, 365 days a year. The inner replica facility permits the database to be referenced and updated while the database is being backed up.

To make a backup using the inner replica facility, specify the -q option.

For details about the inner replica facility and the required products, see the HiRDB Version 9 Staticizer Option Description and User's Guide.

1. You can execute the database copy utility only when HiRDB is active.
2. Execute the database copy utility at the server machine containing the single server or the server machine where the system manager is located.
3. To execute the database copy utility, the unit containing the RDAREA subject to backup processing and the unit in which a backup file is to be created must be active. If you specify x or r in the -M option, the server containing the RDAREA subject to backup processing may not be active, but if you specify s in the -M option, it must be active.

If the disk has enough space, but a message indicating a shortage of disk space is displayed during execution of the database copy utility, the size of the backup file might be greater than 2 gigabytes. HiRDB can only handle files whose size is less than 2 gigabytes. If this is the case, take one of the following actions:

(a) Action 1

Specify multiple backup files. For example, if you are backing up 3 gigabytes of data, specify at least two backup files.

(b) Action 2

Use a regular file on a UNIX system for which the option allowing use of large files (size of 2 gigabytes or more) was specified during the construction of the UNIX file system, or use a HiRDB file system area. For details about creating a large file in a HiRDB file system area, see the HiRDB Version 9 Installation and Design Guide.

(c) Action 3

Create the backup file in a HiRDB file system area in a character special file. For details about creating a large file in a HiRDB file system area, see the HiRDB Version 9 Installation and Design Guide.