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