Concept
Here is the short description of how the process works.
- Make sure your system has at least 2 physical hard drives (hdisk0 and hdisk1).
- Install clean AIX OS on hdisk0. This will become your "MASTER" disk.
- Include required packages (see Prerequisites, below)
- Perfect the OS, install any software that you would like to have as part of the standard OS
- Setup snapshot scripts and create the snapshot
Prerequisites
- All AIX versions require 2 HDD disks. One disk, will call it "MASTER" holds base line OS. The other, let's call it "CLONE", is the disk that the MASTER will be recovering the snapshot to effectively overwriting it every time you will need to restore your snapshot.
- For LPAR's, allocate 2 virtual disks in VIOS.
- All commands must be executed as root.
AIX 5.2 software
bos.alt_disk_install
OR install file set:(lslpp -L bos.alt_disk_install.rte)
AIX 5.3 software
bos.alt_disk_copy
OR install file set: (lslpp -L bos.alt_disk_copy.rte)
bos.alt_disk_install.boot_images
bos.alt_disk_install.rte
bos.msg.en_US.alt_disk_install.rte
AIX 6.1, 7.1 software
- All required packages are present in the default installation
Banner text
Banner will be displayed during the reimaging process to anyone who will be trying to connect to the system via SSH, CONSOLE or TELNET prior to the end of the snapshot recovery process. Touch /etc/banner_default
WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
THE SYSTEM IS BOOTED TO AN ORIGINAL SNAPSHOT DISK
SNAPSHOT RECOVERY IS IN PROGRESS
TO PRESERVE INTEGRITY OF THE SYSTEM DO NOT LOGIN!
Enable banner for SSH
To enable banner for SSH, simply uncomment "Banner" in /etc/ssh/sshd_config
# no default banner path
Banner /etc/banner
NOTE: During the reimaging process /etc/banner_default will be renamed to /etc/banner
Scripts and entries
You will need to add scripts and append standard configuration files as part of this process. Feel free to customize as you wish.
Append /etc/inittab
The line below is used to check whether user requested snapshot restore during the last reboot.
resnap:2:once:/etc/rc.resnapshot >/dev/console 2>&1
Append /etc/profile
Simple notification mechanism if a user is trying to login to the system during the snapshot restore.
#Note: MASTER DISK hdisk0 is intentionally hard coded here
PATH=$PATH:/usr/local/bin
export PATH
if [ `bootinfo -b` == "hdisk0" ]; then
clear
cat /etc/banner_default
while true
do
echo "Are you sure you still wish to login? (y or n) :\c"
read CONFIRM
case $CONFIRM in
y|Y|YES|yes|Yes) break ;;
n|N|no|NO|No)
echo Aborting - you entered $CONFIRM
exit
;;
*) echo Please enter only y or n
esac
done
fi
Create /usr/local/bin/restore_snapshot
Create file /usr/local/bin/restore_snapshot with execute permissions (500). This is the script that you will be executing to request snapshot restore.
#!/bin/sh
#Note: MASTER DISK hdisk0 is intentionally hard coded
# Make sure only root can run our script
if [ "$(id -u)" != "0" ]; then
echo "This script must be run as root" 1>&2
exit 1
fi
if [ `bootinfo -b` != "hdisk0" ]
then
echo "System is booted to the secondary hdisk"
echo "Changing boot device priority to boot to the master hdisk for snapshot restore..."
set -x
bootlist -m normal hdisk0
set +x
echo "Rebooting..."
/usr/sbin/shutdown now -r
else
/etc/rc.resnapshot
fi
AIX 5.2 /etc/rc.resnapshot
Create /etc/rc.resnapshot (chmod 555). This script will be called during OS boot. It will check whether the snapshot restore must start after the reboot.
#!/bin/sh
#Note: MASTER DISK hdisk0 is intentionally hard coded
#Note: CLONE DISK: hdisk1 is intentionally hard coded
if [ `/usr/sbin/bootinfo -b` == "hdisk0" ];then
echo "INFO: System is booted to the master image hdisk."
echo "INFO: Placing banner."
set -x
cp /etc/banner_default /etc/banner
set +x
echo "INFO: Removing altinst_rootvg"
set -x
/usr/sbin/alt_disk_install -X altinst_rootvg
set +x
echo "INFO: Restoring snapshot. If successful, the system will reboot automatically."
echo "INFO: Please wait..."
set -x
/usr/sbin/alt_disk_install -C hdisk1
if [ $? -eq 0 ]; then
echo "rootvg clone operation suceeded!"
echo "Rebooting..."
/usr/sbin/reboot
else
echo "rootvg clone operation failed!"
echo "Aborting..."
fi
set +x
else
set -x
/usr/bin/rm -f /etc/banner
set +x
fi
AIX 5.3, 6.1, 7.1 /etc/rc.resnapshot
Create /etc/rc.resnapshot (chmod 555)
#!/bin/sh
#Note: MASTER DISK hdisk0 is intentionally hard coded
#Note: CLONE DISK: hdisk1 is intentionally hard coded
if [ `/usr/sbin/bootinfo -b` == "hdisk0" ];then
echo "INFO: System is booted to the master image hdisk."
echo "INFO: Placing banner."
set -x
cp /etc/banner_default /etc/banner
set +x
echo "INFO: Removing altinst_rootvg"
set -x
/usr/sbin/alt_rootvg_op -X altinst_rootvg
set +x
echo "INFO: Restoring snapshot. If successful, the system will reboot automatically."
echo "INFO: Please wait..."
set -x
/usr/sbin/alt_disk_copy -d hdisk1 -r
set +x
else
set -x
/usr/bin/rm -f /etc/banner
set +x
fi
Create first snapshot
Please note that you do not "create" the initial snapshot per se.
Your initial snapshot is your current OS hdisk0. What you are doing
is copying the good disk hdisk0 onto the second hdisk1 that after the
whole process is done will become the disk, where you will be testing
stuff. Once test is finished, you will simply execute restore_snapshot
script to request the restore of the snapshot. The restore process will
reboot the OS and will automatically start overwriting the test disk with
the clean OS image. Once that process finishes, the system reboots once
again and you are back on a clone disk.
To initiate the first cloning process, simply execute:
/usr/local/bin/restore_snapshot
And you are all set!
Important commands
#Display AIX disk information
#CURRENT BOOT DISK: bootinfo –b
#ALL DISKS: lspv
#DISK DETAILS: lscfg -vl hdisk0
#MOUNT MASTER WHEN BOOTED ON TEST
#alt_rootvg_op –W –d hdisk0
#UNMOUNT MASTER WHEN BOOTED ON TEST
#alt_rootvg_op –S
#[alternatively specify –t to rebuild boot image.
Not recommended for minor changes.
Helpful links
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