Backing Up the Operating System in AIX 4.1

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mksysb tape images

   ---------------------------------------------------------  
  |  Bosboot  |  Mkinsttape  |  Dummy TOC  |    rootvg      | 
  |   Image   |     Image    |    Image    |     data       | 
  |----------- -------------- ------------- ----------------| 
  |<----------- Block size 512 ----------->| Blksz defined  | 
  |                                        | by the device. | 
   ---------------------------------------------------------  

    blocksize:              512 
    format:                 raw image 
    files:                  kernel device drivers 

    blocksize:              512 
    format:                 backbyname 
    files:                  ./image.data, ./tapeblksz, 
                            ./bosinst.data and commands 

    blocksize:              determined by tape drive configuration 
                            on create 
    format:                 backbyname 
    files:                  rootvg, mounted JFS file systems 

mksysb file image

Options in creating a mksysb

Creating to a tape drive

NOTE: A mksysb tape is only bootable when it is created to a tape drive.

1. Using SMIT:

   Fill in the correct device name to be used. Press Enter to start the backup. If more than one tape is required, SMIT will give a prompt to change the tape.

       smit mksysb 
       Backup DEVICE or FILE                         [/dev/rmt#] 
       Create MAP files?                             no 
       EXCLUDE files?                                no 
       Make BOOTABLE backup?                         yes 
            (Applies only to tape) 
       EXPAND /tmp if needed?                        yes 
            (Applies only to bootable tape) 
       Number of BLOCKS to write in a single output  [ ] 
            (Leave blank to use a system default) 
   

2. Execute:

    mksysb -i /dev/rmt# 2>/tmp/mksysb.err 

WARNING: If the device blocksize is set to 0, mksysb will use a hardcoded value of 512 for the fourth image. This can cause the create and restore to take 5-10 times longer than expected.

Creating a mksysb

1. The file system /tmp must have a least 10MB free just prior to creating the mksysb.

2. Unmount all nonessential file systems to reduce the size of the mksysb backup. Try to limit the mksysb to only system file systems if possible.
   
3. Be sure to record how many volume groups, what disks they are located on, and the location of each disk. Hdisk#'s are not retained.

       lsvg 
       lsvg -p vgname 
       lsdev -Cc disk 
   

Creating to a file

1. From SMIT:

   A mksysb image file is created in the same manner as the bootable tape described in the section, Creating to a tape Drive. The only difference is as d follows:

          smit mksysb 
        Backup DEVICE or FILE              [/path/file] 
        Make BOOTABLE backup?              no 
             (Applies only to tape) 
   

2. Execute:

    mksysb -i /path/file 2>/tmp/mksysb.err 

Verifying a system backup will correctly restore

    tctl -f /dev/rmt# rewind 
    restore -s4 -Tvqf /dev/rmt#.1 > /tmp/mksysb.log 

Restoring

    not enough physical volumes 

1. Boot in SERVICE mode
   1. If the system has a key, turn it to service. If the system is keyless, consult the model's documentation.
   2. Insert the mksysb tape into the tape drive.

   3. Reboot the system by running the command shutdown -Fr or by pressing the Reset button twice.

2. The system should now boot from the mksysb tape.

   If the tape will not boot, remove the tape and boot from install media such as a cdrom or tape.

   NOTE: Multiprocessor systems display a maintenance menu called a BUMP MENU. This is a hardware menu. For more information, consult the model's documentation.

3. A message should state, press F1 or 1 for Console. Press the F1 key for a graphics display and the 1 key for ascii display, and press Enter.

4. Press 1 for English, if asked.

5. The Installation and Maintenance menu should display. If the system was booted from media other than the mksysb tape, the tape can now be inserted into the tape drive. Follow the steps listed in the subsection, "Restore menus".

6. After the restore is complete, turn the key to Normal. If the system is keyless, this is automatic.

7. The system will reboot once. The system events system events from inittab and a login prompt should appear.

   NOTE: If there are volume groups other than rootvg, there may be error messages prior to a login prompt. Ignore these messages unless they prevent the prompt from appearing.

   NOTE: Total restore time varies from system to system. A good rule of thumb, providing the device blocksize is not set to 0, is twice the amount of time it took to create the mksysb.

   If the blocksize of the source tape drive was 0, the mksysb would have been created with a blocksize of 512. In this case, there is a restore time of 5-10 times longer than is normally expected.

8. If there are other disks which contain other volume groups, they will need to be imported into the newly created ODM. No references to the other volume groups exist prior to this step. This can be done by completing the following steps:
   1. Match the newly labeled hdisk#'s to the appropriate SCSI location IDs. Do not assume that the hdisks will be at the same location. The disks are re-numbered from lowest to highest location number and labeled accordingly.

      Execute:

          lsdev -Cc disk 
      

   2. Import each volume group into the new ODM. The following must be run for each non-rootvg volume group. However, only one disk per volume group need be selected.

      Execute:

          importvg -y vgname hdisk# 
      

      For example, if there is another vg named "data" and it resides on "hdisk3" and "hdisk4", execute:

          importvg -y data hdisk3 
      

   3. Activate each non-root volume group by entering:

          varyonvg vgname 
      

   4. Restart the system to resync the ODM and mount all file systems, by executing:

          shutdown -Fr 
      

      NOTE: If the system is not to be rebooted again, use mount -a in place of shutdown. This will mount all the new file systems. A system reboot should be scheduled as soon as possible to be sure that everything is in sync.

   5. A login prompt should now be displayed.

Restore menus

1. Installation and Maintenance Menu, select (3)

       1)  Start Installation Now with Default Settings 
       2)  Change/ Show Installation Settings and Install 
       3)  Start Maintenance Mode for System Recovery 
   

2. Maintenance Menu, select (4)

       1)  Access a Root Volume Group 
       2)  Copy a System Dump to Removable Media 
       3)  Access Advanced Maintenance Functions 
       4)  Install from a System Backup 
   

3. Choose a Tape Drive, select (# of tape)

           Tape Drive              Path Name 
       1. tape /scsi/8mm         /dev/rmt# 
   

4. Select a Language, if asked, select (# for language)

       1)  Type 1 and press Enter to have English during install. 
   

5. Installation and Maintenance Menu, select (2)

       1)  Start Installation Now with Default Settings 
       2)  Change/ Show Installation Settings and Install 
       3)  Start Maintenance Mode for System Recovery 
   

6. System Backup Installation and Settings, select (1)

          Setting:                             Current Choice(s): 
       1. Disk(s) where you want to install......... hdisk0 
          Use Maps.................................. No 
       2. Shrink File Systems....................... No 
       0. Install with the settings listed above. 
   

7. Change Disk(s) Where You Want to Install, select (# of disk(s)),(0)

   Type the numbers for the disk to be used for installation and press Enter. The current choice is indicated by >>>. To deselect a choice, type the corresponding number and press Enter. At least one bootable disk must be selected. Choose the location by SCSI ID.

          Name    Location Code   Size (MB)   VG Status   Bootable 
       1. hdisk0  00-01-00-0,0      305       rootvg        yes 
       2. hdisk1  00-01-00-1,0      400       rootvg        yes 
       0. Continue with the choices indicated above 
   

8. To shrink the file systems to reclaim free space allocated to the file systems, select option 2 so that the setting is set to Yes. To restore file systems with the same allocated space as the original system, then make sure option 2 is set to No.

9. System Backup Installation and Settings, select (0 to continue)

          Setting:                                Current Choice(s): 
       1. Disk(s) where you want to install......... hdisk0 
       2. Use Maps.................................. No 
       3. Shrink File Systems....................... No 
       0. Install with the settings listed above. 
   

10. There will then be a message stating, select Y to continue.

Restoring individual files from a mksysb tape

1. To restore individual files or directories from a mksysb tape, obtain the blocksize of the fourth image. To obtain this information, enter:

       cd /tmp 
       tctl -f /dev/rmt# rewind  (# to be replaced by a number) 
       chdev -l rmt# -a block_size=512 
       restore -s2 -xqdvf /dev/rmt#.1 ./tapeblksz 
       cat ./tapeblksz 
   

   The output given will be the blocksize the tape drive was set to when the mksysb was made.

2. The blocksize of the tape drive needs to be set accordingly, by entering:

    chdev -l rmt# -a block_size=[number in the ./tapeblksz file] 
   

3. The files or directories need to be restored by entering:

   cd /    (if the file is to be restored to its original place)
   tctl -f /dev/rmt# rewind
   restore -s4 -xqvf /dev/rmt#.1 ./dir/filename    (for one file)

   Or

   restore -s4 xqdvf /dev/rmt#.1 ./dir    (for all files in the directory).

[ Doc Ref: 90605209414758     Publish Date: May. 19, 2000     4FAX Ref: 8165 ]