AIX Updates with Multibos
Chris Gibson
What is multibos?
• Introduced with AIX 5.3 TL3.
• Create and maintain two separate, bootable instances of
the AIX OS within the same root volume group (rootvg).
• Standby BOS.
• Install, update and customize a standby instance of the
AIX OS.
• By default, the BOS file systems in rootvg(/, /usr, /var,
and /opt) and the BLV are copied. All other file systems
and LVs are shared between BOS instances.
• Similar alternate disk: no additional disk, some LV
shared between instances.
AIX Updates with Multibos.
• Valuable in environments with tight maintenance
windows.
• Apply a new TL or SP. AIX migration not
supported….yet!
• Only need a small outage at a convenient time to reboot
the system.
• Reduce the size of the after-hours effort.
• Backing out from an AIX TL update is also easier.
Getting Started
• AIX 5.3 with TL3 or higher.
• Free space in rootvg for a copy of each BOS logical
volume (# lsvg rootvg | grep FREE ).
• If all of the requirements can’t be met, then a traditional
update should be performed.
• Document the system and perform a mksysb before
performing any maintenance activity.
Creating a Standby BOS Instance
• Example: we’ll upgrade an AIX 5.3 system from TL4 to
TL6.
• Remove any previous standby BOS instance using
“multibos –R.”
• Preview the operation first (using “multibos –sXp”).
• Review the multibos log for any errors (i.e., “alog –
of/etc/multibos/logs/op.alog”).
Creating a Standby BOS Instance,
cont.
• Create the standby BOS instance. This may take several
minutes and should create a new LV and file system for
each BOS copy.
• Each new LV and file system is prefixed by bos_.
# multibos –sX
# lsvg -l rootvg | grep bos
bos_hd5 boot 1 1 1 closed/syncd N/A
bos_hd4 jfs 4 4 1 closed/syncd /bos_inst
bos_hd2 jfs 48 48 1 closed/syncd /bos_inst/usr
bos_hd9var jfs 21 21 1 closed/syncd /bos_inst/var
bos_hd10opt jfs 4 4 1 closed/syncd /bos_inst/opt
Creating a Standby BOS Instance,
cont.
• Start a multibos shell and verify the standby BOS and its
current TL.
# multibos -S
Initializing multibos methods ...
Mounting all standby BOS file systems ...
Mounting /bos_inst
Multibos Root Shell
Starting multibos root shell ...
# oslevel -s
5300-04-01
# exit
Unmounting all standby BOS file systems ...
Log file is /etc/multibos/logs/op.alog
Return Status = SUCCESS
Updating and Booting the Standby
BOS
• Apply TL6 to the standby BOS. The TL6
lppsource is mounted from our NIM master.
• Perform a preview operation and then execute
the actual update to the standby instance. Again,
checking the log file for any issues.
# mount nimmast:/export/lpp_source/lpp_sourceaix530603 /mnt
# multibos -Xacp -l /mnt
# multibos -Xac -l /mnt
Updating and Booting the Standby
BOS, cont.
• We’ve now successfully applied TL6 to the standby
BOS. Start a multibos shell and verify that the standby
BOS has been updated.
# multibos –S
...
# oslevel -s
5300-06-03-0732
# exit
Ready to boot the standby BOS
• BOS may be upgraded during the day, but the system may be
restarted after hours depending on the available outage windows for
this system.
• Verify the bootlist and ensure that the BLV is set to the standby BOS
(bos_hd5).
• Check the correct BLV. Compare the output from bootlist with
“Welcome to AIX” banner.
# bootlist -m normal -ov
‘ibm,max-boot-devices’ = 0x5
NVRAM variable: (boot-device=/vdevice/v-scsi@30000004/disk@8100000000000000:2 /vdevice/v-
scsi@30000004/disk@8100000000000000:4)
Path name: (/vdevice/v-scsi@30000004/disk@8100000000000000:4)
hdisk0 blv=bos_hd5
Path name: (/vdevice/v-scsi@30000004/disk@8100000000000000:2)
hdisk0 blv=hd5
---------------------------------------------------------------------
Welcome to AIX.
boot image timestamp: 02:24 06/05
The current time and date: 02:25:27 09/03/2007
number of processors: 1 size of memory: 4096MB
boot device: /vdevice/v-scsi@30000004/disk@8100000000000000:4
kernel size: 14154989; 64 bit kernel
---------------------------------------------------------------------
Booting the Standby BOS
• Reboot the system now with the “shutdown –Fr”
command. After the reboot, confirm the TL level via
“oslevel –r”. Verify which BLV the system booted from
with the “bootinfo –v” command.
• Multibos LVs and file systems are now open and
mounted. The original file systems are renamed with a
bos_ prefix but their original LV names are preserved.
Back out a TL or SP
• If you need to back out of the update and return to the
previous TL, all that’s required is to boot the previous
(“original”) BOS instance.
• Set the bootlist and verify that the BLV is set to the
previous BOS instance (hd5).
# bootlist -m normal hdisk0 blv=hd5 hdisk0 blv=bos_hd5
# bootlist -m normal -o
hdisk0 blv=hd5
hdisk0 blv=bos_hd5