Unix Articles & FAQ

The mksysb command creates a backup of the operating system (that is, the root volume group). You can use this backup to reinstall a system to its original state after it has been corrupted. If you create the backup on tape, the tape is bootable and includes the installation programs needed to install from the backup.

The file-system image is in backup-file format. The tape format includes a boot image, a bosinstall image, and an empty table of contents followed by the system backup (root volume group) image. The root volume group image is in backup-file format, starting with the data files and then any optional map files.

FAQ
1. The image the mksysb command creates does not include data on raw devices or in user-defined paging spaces.
2. If you are using a system with a remote-mounted /usr file system, you cannot reinstall your system from a backup image.
3. Specify map file to make sure that the mksysb allocation is exactly the same. It is extremely useful if your rootvg have more than one hard disk and most of the filesystems are mirrored, some filesystem is multi-volume and they are not mirrored because of space problem.  Mksysb restore will fail if the map file is not specified as mksysb creates filesystem in sequence. After mksysb creates a big filesystem which is not mirroed and one of the hard disk may full. Consequently all the of mirroed filesystems cannot be created and mksysb stuck uo.
4. The bosinsta.data is the most important parameter of rootvg
   Sample layout of bosinst.data
    control_flow:
    CONSOLE =
    INSTALL_METHOD = overwrite
    PROMPT = yes
    EXISTING_SYSTEM_OVERWRITE = yes
    INSTALL_X_IF_ADAPTER = yes
    RUN_STARTUP = yes
    RM_INST_ROOTS = no
    ERROR_EXIT =
    CUSTOMIZATION_FILE =
    TCB = no
    INSTALL_TYPE =
    BUNDLES =
    SWITCH_TO_PRODUCT_TAPE =
    RECOVER_DEVICES = yes  <----  (All the hardware device and system setting will be the same after restore)
    BOSINST_DEBUG = no

    If you specify RECOVERY_DEVICES = no, it is used to rebuild a new AIX system, the hardware device will be rebulid, you have to tailor the TCPIP address and hostname. The AIO parameter will be reset to 'NO".