The IBM AIX UNIX differs from other UNIXs because of two main features: the Object Database Manager (ODM) and the Logical Volume Manager (LVM). Due to the ODM and the LVM, as well as the ability to have multiple volume groups, a complete system archive made with cpio or tar will not restore properly. Attempting to restore such an archive on a running system can potentially crash the machine. Creating a mksysb to a tape drive will create a bootable tape that will allow the system's ODM and LVM to be restored properly.
The following is a description of mksysb's four images.
+---------------------------------------------------------+ | Bosboot | Mkinsttape | Dummy TOC | rootvg | | Image | Image | Image | data | |-----------+--------------+-------------+----------------| |<----------- Block size 512 ----------->| Blksz defined | | | by the device | +---------------------------------------------------------+
Image #1: The bosboot image contains a copy of the system's kernel and specific device drivers, allowing the user to boot from this tape.
blocksize: 512
format: raw image
files: kernel device drivers
Image #2: The mkinsttape image contains files to be loaded into the RAM file system when you are booting in maintenance.
blocksize: 512
format: backbyname
files: ./image.data, ./tapeblksz,
./bosinst.data and commands
Image #3: The dummy image contains a single file containing the words "dummy toc". This image is used to make the mksysb tape contain the same number of images as a BOS Install tape.
Image #4: The rootvg image contains data from the rootvg volume group (mounted JFS file systems only).
blocksize: determined by tape drive configuration
on create
format: backbyname
files: rootvg, mounted JFS filesystems
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 to a file will create a non-bootable, single-image backup and restore archive containing only rootvg JFS mounted file systems.
NOTE: A mksysb tape is only bootable when it is created to a tape drive.
smit mksysbA dialog box will appear.
smit mksysb
Backup DEVICE or FILE [/dev/rmt#]
Create MAP files? no
EXCLUDE files? no
List files as they are backed up? no
Generate new /image.data file? yes
EXPAND /tmp if needed? yes
Disable software packing of backup? no
Number of BLOCKS to write in a single output [ ]
(Leave blank to use a system default)
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.
lsvg
lsvg -p <vgname>
lsdev -Cc disk
A mksysb image file is created in the same manner as the bootable tape (shown in previous portion of this section). The only difference is shown in the second line of the dialog box:
smit mksysb
Backup DEVICE or FILE [/path/file]
Number of BLOCKS to write in a single output [ ]
(Leave blank to use a system default)
mksysb -i /path/file 2>/tmp/mksysb.err
The only method to verify that a system backup will correctly restore with no problems is to actually restore the mksysb onto another machine. This should be done following each individual company's DISASTER RECOVERY PLAN.
To minimize problems due to tape media damage, perform the following tests.
WARNING: These tests only verify that the tape media can be read and will not guarantee that a mksysb will be restored successfully.
The only way to verify that the mksysb tape will successfully boot is to
bring the machine down and boot from the tape. No data needs to be restored.
NOTE: To boot a keyless system or a system with multiprocessors in
Service mode, consult the model's documentation or contact your AIX support representative for
assistance.
WARNING: Having the PROMPT field in the bosint.data file set
to no causes the system to begin the mksysb restore automatically
using preset values with no user intervention.
If the state of PROMPT is unknown, it can be set during the boot process.
After answering the prompt to select a console during the startup process, a rotating
character will be seen in the lower left of the screen. As soon as this
character appears, type 000 and press Enter. This will set the prompt variable
to yes.
To check a mksysb tape to see how the PROMPT is set, run the following
while in Normal mode:
NOTE: Multiprocessor systems display a Maintenance Menu called a BUMP
MENU. This is a hardware menu. For more information, consult the model's
documentation or contact your AIX support representative for assistance.
Be sure to select all physical volumes required for the root volume group.
This is especially important if there is mirroring. Mirrored disks must be
selected at the time of installation or an error like the following will be
seen:
If the system will not boot, remove the mksysb tape and boot from install
media such as a CD-ROM 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 or contact your AIX support center for assistance.
NOTE: If the system has volume groups other than rootvg, there may
be error messages prior to a login prompt. Ignore these messages unless they
prevent you from obtaining the prompt.
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, the restore time will be 5-10 times longer
than normal.
Enter:
For example, if there is another vg named "data" and it resides on hdisk3
and hdisk4, enter:
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. However, a
system reboot should be scheduled as soon as possible to be sure that
everything is in sync.
Type one or more numbers for the disks 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 its SCSI ID.
The output that is given is the blocksize to which the tape drive was set
when the mksysb was made.
OR
Data verification
smit lsmksysb
A dialog box will appear.
DEVICE or FILE [/dev/rmt#]
Number of BLOCKS to read in a single input [ ]
(Leave blank to use a system default)
tctl -f /dev/rmt# rewind
restore -s4 -Tvqf /dev/rmt#.1 > /tmp/mksysb.log
Boot verification
chdev -l rmt# -a block_size=512
tctl -f /dev/rmt# rewind
cd /tmp
restore -s2 -xvqf /dev/rmt#.1 ./bosinst.data
Check the PROMPT field in the control_flow stanza.
shutdown -Fr
Restoring a mksysb
not enough physical volumes.
lsdev -Cc disk
importvg -y <vgname> hdisk#
importvg -y data hdisk3
varyonvg <vgname>
shutdown -Fr
Restore menus
1) Start Installation Now with Default Settings
2) Change/Show Installation Settings and Install
3) Start Maintenance Mode for System Recovery
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
Tape Drive Path Name
1. tape /scsi/8mm /dev/rmt#
1) Type 1 and press Enter to have English during the install.
1) Start Installation Now with Default Settings
2) Change/Show Installation Settings and Install
3) Start Maintenance Mode for System Recovery
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.
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
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.
WARNING: All data on the selected disks will be destroyed. Do you
wish to continue? "Y/N"
Select Y.
Restoring individual files from a mksysb tape
NOTE: If you want to exclude certain files from the backup, create the
/etc/exclude.rootvg file, with an ASCII editor, and enter the patterns of
file names that you do not want included in your system backup image. The
patterns in this file are input to the pattern matching conventions of the
grep (which uses regular expression) command to determine which files will be
excluded from the backup. If
you want to exclude files listed in the /etc/exclude.rootvg file, select the
Exclude Files field and press the Tab key once to change the default value
to yes.
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
chdev -l rmt# -a block_size=[number in the
./tapeblksz file]
cd / (if the file is to be restored to its original place)
tctl -f /dev/rmt# rewind
restore -s4 -xqdvf /dev/rmt#.1 ./dir/filename (for one file)
restore -s4 -xqdvf /dev/rmt#.1 ./dir (for all files in dir)
For example, to exclude all the contents of the directory called scratch, edit the exclude file to read as follows:
/scratch/
For example, to exclude the contents of the directory called /tmp, and avoid excluding any other directories that have /tmp in the pathname, edit the exclude file to read as follows:
^./tmp/
[ Doc Ref: 90605209714762 Publish Date: Oct. 16, 2001]