AIX OS Migration

Migrating an AIX system to AIX 7.3 doesn't have to mean downtime disasters or data loss risks. Using NIMADM (NIM Alternate Disk Migration), you create a bootable copy of your rootvg on a spare disk—preserving configs, users, and data while enabling easy rollback. This method leverages your NIM master for a smooth, network-driven upgrade.

In this guide, we'll walk through every step: NIM setup, client prep, migration execution, post-steps, and rollback. Perfect for production environments with apps like Db2 or Oracle.

Prerequisites on NIM Server

Before nimadm can work, your NIM master needs two core resources:

• lpp_source: AIX 7.3 package repository from install ISOs.
• SPOT: Bootable image environment built from the lpp_source.

Create LPP Source from AIX 7.3 TL3 ISOs

Start with DVD 1:

# nim -o define -t lpp_source -a server=master -a location=/export/lpp_source/lpp_7300-03-00 \

-a source=/software/aix/AIX_v7.3_Install_7300-03-00-2446_DVD_1_of_2_122024_LCD8299201.iso \

-a packages=all lpp_7300-03-00

Add DVD 2:

# nim -o update -a packages=all \

-a source=/software/aix/AIX_v7.3_Install_7300-03-00-2446_DVD_2_of_2_122024_LCD8299301.iso \

lpp_7300-03-00

Build and Customize SPOT

Create SPOT (if needed):

# nim -o define -t spot -a server=master -a location=/export/spot -a source=lpp_7300-03-00 spot_7300-03-00

Install required filesets:

# nim -o cust -a lpp_source=lpp_7300-03-00 -a filesets=bos.alt_disk_install.rte spot_7300-03-00

nim -o cust -a filesets=bos.alt_disk_install.boot_images -a lpp_source=lpp_7300-03-00 spot_7300-03-00

Verify everything:

# lsnim | grep 7300-03-00

# nim -o check spot_7300-03-00

Client-Side Prep: NIM Config and Disk Setup

Configure NIM Client and Master Hosts

On client, update /etc/hosts:

192.168.1.20 nimclient

On NIM master:

192.168.1.10 nimserver

Register client:

# smitty nim_mkmac  # (standalone, chrp, 64-bit, nimsh)

Initialize client:

# mv /etc/niminfo /etc/niminfo.old

# smitty niminit  # (match details above)

Prepare Alternate Disk

List disks:

# lspv | grep rootvg

# Example: hdisk0 (active rootvg), hdisk1 (free)

Clean up if needed:

# varyoffvg altinst_rootvg

# alt_rootvg_op -X altinst_rootvg

(Optional) Backup:

# nim -o define -t mksysb -a server=master -a location=/export/mksysb/<client>_pre7300.mksysb -a source=<client> <client>_mksysb

Note: hd5 (boot LV) needs 40MB contiguous space. LV encryption supported in 7.3 TL3+.

Execute NIMADM Migration (From NIM Master)

Launch the magic:

# nimadm -j nimcache2 -c <client_name> -s spot_7300-03-00 -l lpp_7300-03-00 -d hdisk1 -Y

Monitor:

# tail -f /var/adm/ras/nimadm.log

Reboot and Post-Migration Tasks

During your change window:

# shutdown -Fr  # Boots to new hdisk1 rootvg

Immediate checks:

# oslevel -s  # Should show 7300-XX-XX

# cfgmgr

# lsdev -Cc adapter

# ifconfig -a

Activate VGs/filesystems:

# varyonvg datavg

# mount -a

Verify services:

# lssrc -a  # Db2, MQ, etc.

Clean NIM:

# nim -o deallocate -a resource=spot_7300-03-00 <client_name>

# nim -o deallocate -a resource=lpp_7300-03-00 <client_name>

Update bootlist:

# bootlist -m normal -o  # Confirm new hdisk

Validation Checklist

Check	Command	Expected
OS Level	oslevel -s	7300-XX-XX
RootVG Disk	bootlist -m normal -o	New hdiskX
Filesystems	df -g	All mounted
NIM Info	cat /etc/niminfo	Updated
Services	lssrc -a	All active

Rollback Plan

Boot failure?

• Enter SMS, select original rootvg disk.
• Restore mksysb: nim -o restore <client>_mksysb.

Pro Tips: TCB changes may apply; test apps thoroughly. Non-rootvg VGs and networks often need manual varyon/mount.

This method minimizes risk—migrate confidently!