Backup

Question 1: Can you make a backup of just a table?

Answer

No, you cannot. However, you can achieve this with one of the following methods:

Store one table in one RDAREA and make a backup of the RDAREA.
Use the database reorganization utility (pdrorg command) to unload each table.

Question 2: Can you make a backup that consists of only the changes made since the previous backup?

Answer: Yes, you can. HiRDB supports the differential backup facility. This facility backs up only the information that has changed (differential information) since the previous backup was made. This facility can reduce the amount of time spent making backups. The differential backup facility should be used when the database is large but the volume of updating is small. For details of the differential backup facility, see 6.5 Acquiring a differential backup.

Question 3: If an error occurs in a particular RDAREA after all RDAREAs have been backed up with the -a option specified in the pdcopy command, can you recover only that RDAREA from the backup copy of all RDAREAs?

Answer: Yes, you can. A particular RDAREA can be recovered by specifying its name in the pdrstr command.

(2) Difference between the pdfbkup and pdcopy commands

Question 1: Can I use a backup (backup of a HiRDB file system area) acquired with the pdfbkup command as the input file for the pdrstr command?

Answer: No, a backup acquired with the pdfbkup command can be used only with the pdfrstr command.

Question 2: Can I make a backup with the pdfbkup command while HiRDB is running?

Answer: Yes, you can. For details, see 6.7 Backup acquisition using backup-hold (backup without using the pdcopy command).

(3) Backing up the master directory RDAREA

Question 1: Can I back up RDAREAs while HiRDB is running?

Answer

Yes, you can. However, if the master directory RDAREA is included, one of the following backup acquisition modes must be used:

Referencing-permitted mode (-M r specified)
Updatable mode (-M s specified)

Question 2: If the -a option (back up all RDAREAs) is specified in the pdcopy command, will the master directory RDAREA be included? If so, do I need to start HiRDB with the pdstart -r command?

Answer

The master directory RDAREA will be included.

HiRDB must be started with the pdstart -r command, not just when the master directory RDAREA is backed up, but when both the following conditions are satisfied:

The master directory RDAREA is included in the backup
The referencing/updating-impossible mode (-M x specified) is specified as the backup acquisition mode

(4) Even though there is available space on the disk, a disk space shortage occurs during execution of the pdcopy command

Question: Why does a disk space shortage occur during execution of the pdcopy command, even though there is available space on the disk?

Answer

The following are possible reasons:

The permitted maximum size for the kernel parameter has been exceeded.

In this case, change the kernel parameter's value. You can also solve the problem by specifying multiple backup files. However, if the OS does not support large files, you must set the disk partition size to 2 GB or less to handle multiple files.

Appendix A.9 Backup

(1) Backup acquisition unit

(2) Difference between the pdfbkup and pdcopy commands

(3) Backing up the master directory RDAREA

(4) Even though there is available space on the disk, a disk space shortage occurs during execution of the pdcopy command