Creating an accumulation-differential backup

To create an accumulation-differential backup, you execute the pdcopy command with c specified in the -d option. Creating an accumulation-differential backup might reduce the size of the backup file to be used for restoration. For example, if the same page is updated every day, all the update information for that page is merged, so the size of the backup file to be used for restoration is reduced. The following figure illustrates the concept of an accumulation-differential backup.

Figure 6-2 Concept of an accumulation-differential backup

[Figure]

Explanation

When the accumulation-differential backup is made on Wednesday, the differential backups made on Monday and Tuesday will not be used for database restoration. The backups necessary for database restoration are the full backup and the accumulation-differential backup made on Wednesday.
Whether an accumulation-differential backup is to be made from the full backup or the previously collected accumulation-differential backup is specified in the -d option of the pdcopy command.

Organization of this subsection: (1) Precautions; (2) Examples of making accumulation-differential backups

As an example, you might wish to perform the following operations when making accumulation differential backups:

Make a full backup on Sunday.
Make differential backups on Monday and Tuesday.
On Wednesday, make an accumulation-differential backup for Monday through Wednesday.^#
Make differential backups on Thursday and Friday.
On Saturday, make an accumulation-differential backup for Thursday through Saturday.^#

#: Following is an example of specifying the pdcopy command for the above Wednesday and Saturday tasks. Before you execute the pdcopy command, use the pdlogswap command to swap system log files.

 
pdlogswap -d sys -w
pdcopy -m /rdarea/mast/mast01 -M r -g backupg1 -b /pdcopy/backup03
-d c -K /pdcopy/admfile -o /pdcopy/rfile

Explanation

-m: Specifies the name of the first HiRDB file in the master directory RDAREA.

-M: Specifies the referencing-permitted mode as the backup acquisition mode.

-g: Specifies the name of the differential backup group; (S) need not be specified.

-b: Specifies a name for the backup file (accumulation-differential backup file name).

-d: Specifies the backup type:: a: Full backup; b: Accumulation-differential backup since the most recent full backup; c: Accumulation-differential backup since either the previously collected accumulation-differential backup or the previously collected full backup, whichever is most recent; d: Differential backup

-K: Specifies the name of the HiRDB file system area in which the differential backup management file is to be stored.

-o: Specifies the name of the history file for differential backups.

6.5.4 Creating an accumulation-differential backup

(1) Precautions

(2) Examples of making accumulation-differential backups