If nimadm fails, it’s best to first look at the logs to determine the cause of failure. If there isn’t enough information in the logs to determine the problem it may be necessary to run nimadm in debug mode.
Debug mode can be enabled by using the –D option if you are using command line or by setting Debug output? to yes if you are using smitty nimadm

There are many times that problems with nimadm can be resolved by using disk caching. That will eliminate issues that arise due to slow networks and/or NFS issues. Disk caching can be enabled by using the –j option and specifying the volume group to use on the nim master to perform the nimadm. If you are using smitty nimadm you would specify the volume group to use with DISK CACHE volume group name.

Since this is a migration you will want to verify that your system is in a consistent state before performing the nimadm.
On the client, run the following commands:
# oslevel –s this will tell you what level the system is currently at
# oslevel –sq the highest level that is output should match the oslevel –s output from above.
# lppchk –v this should return to the prompt with no output
# lsvg rootvg | grep SIZE verify the size is at least 32 megabytes
# bosboot –ad /dev/ipldevice verify the boot image is created and there are no errors.

For additional checks you may want to do prior to the nimadm you may want to review the Preparing to Migrate document at

If you have a pre-migration script resource defined on your nim master you can specify for that to be run. If you do it will be run during phase 4 of the nimadm process.

If you get an error similar to the following:
0505-205 nimadm: The level of bos.alt_disk_install.rte installed in SPOT <spot> ( does not match the NIM master’s level
You will need to verify the level of bos.alt_disk_install.rte on the master and in the spot.
To check the master:
# lslpp –l bos.alt_disk_install.rte
To check the spot:
# nim –o showres <spot> | grep bos.alt_disk_install.rte
If the levels aren’t the same (or if the spot doesn’t have the fileset) you can install/update it with smitty nim_inst_all
Then select the spot and the lpp_source that has the same level fileset that is on the master, then for Software to Install enter bos.alt_disk_install.rte

Although there are many different kinds of errors possible with nimadm, having the correct level of bos.alt_disk_install.rte in the spot and doing the pre-migration checks and using the cache option will eliminate most of them. For anything else a debug output will probably be needed for further analysis.