Installation Guide and Reference

Troubleshooting an Installation from a System Backup

This section describes solutions for common problems when installing from a system image created with the mksysb command.

The section discusses the following topics:

Bootup Failure

If a backup tape fails to boot, you can still install by using a mksysb image stored on the tape.

Boot the machine from the product media (Volume 1 if there is more than one volume), then install the backup from Maintenance mode. Refer to Introduction to Base Operating System Installation for instructions on booting. Follow the instructions to the point when the Welcome to the Base Operating System Installation and Maintenance screen displays.

Booting from the Product CD-ROM

Complete the following steps when the Welcome screen is displayed:

Choose the Start Maintenance Mode for System Recovery option.
Choose the Install from a System Backup option.
Choose the drive containing the backup tape.
The system reads the tape and begins the installation.
Do not remove the CD from the CD-ROM drive.
The system installs the kernel and device support required on the target system from the CD.
Return to step 8 in the Installing a System Backup on the Source Machine procedure and continue the instructions for installing the backup.
Note: The Use Maps option is not supported in Maintenance Mode. For more information on the maps options in Maintenance Mode, refer to the Installing a System Backup on the Source Machine procedure in the Creating and Installing System Backups chapter.

Problems with mksysb Image Configuration on System Backup Tapes

Bootable mksysb tapes comprise the following images: the boot image, the BOS Install/Maintenance image, the table of contents image and the system backup image. The system backup image is the actual backup of the files in the rootvg in all JFS-mounted file systems.

The first three images must be created with a tape block_size value of 512. The mksysb command ensures that the block size is 512 when these images are created. There are no restrictions on the block size used for the fourth (system backup image) on the tape. The block size of the system, before it was temporarily set to 512, is used for the fourth image on the tape.

The value of the block size must be saved in the /tapeblksz file in the second image on the tape. The second and fourth images are stored in backup/restore format. Again, mksysb ensures the correctness of the tapes created using the mksysb command.

If there are problems with the bosinst.data file, the image.data file, or the tapeblksz file, they can be restored from the second image on the tape and checked. These files, as well as commands necessary for execution in the RAM filesystem (when running in maintenance mode after booting from the tape), are stored in the second image.

Restoring a File from the Second Image or Tape

To restore a file from the second image, follow these steps:

Be sure the tape block size is 512 by entering the following command:
```
# lsattr -E -l rmt0
```
If the block size is not correct, use the following command to set it to 512:
```
# chdev -l rmt0 -a block_size=512
```
Make sure the tape is rewound. If the tape is not rewound, enter the following command:
```
# tctl -f /dev/rmt0 rewind
```
Extract the necessary files by entering:
```
# restore -xvq -s2 -f /dev/rmt0.1 .filename
```
Note: The filename should be the full path, and always preceded with a . (dot character), such as ./tapeblksz.
Rewind the tape by entering:
```
# tctl -f /dev/rmt0 rewind
```
Change the block size back to its original value, if necessary.

Suggestions for Reported Problems with mksysb Backup Installations

The following troubleshooting tips apply to reported problems with installations from a mksysb image:

Check that you have sufficient free blocks in the file systems to write temporary files.
Check that each file system has at least 500 blocks free when the mksysb backup image is made. The system needs work space in each file system when installing from a mksysb backup image.
Check that you are using the correct tape type for the density setting that you selected.
Check that the tape is not write protected.
Clean the tape drive at the recommended intervals and use only approved data-grade tapes (not video tapes for 8 mm).
Check that 7206 4-mm Digital Audio Tape (DAT) tape drives are using only DAT tapes marked with the Dataphone Digital Services (DDS) symbol. Any other DAT tapes (for example, voice grade) cannot be used.
Check the /smit.log file for any errors from SMIT.
Check that your mksysb backup image contains an image.data file. If you create the mksysb backup image through Web-based System Manager or SMIT, it is done automatically. If you run mksysb from the command line, you must either run the mkszfile command first, or use the -i flag with the mksysb command.