Edit: The infocenter site no longer works. It is fun to look back at migrating from POWER5 to POWER6.
Originally posted January 20, 2009 on AIXchange
I wrote an AIXchange blog entry about mksysb migrations using NIM more than a year ago. At the time I said I’d write more after testing it out. However, after seeing in the comments from that post that others had used it (and in one case, written the IBM Redbook about it), it moved down on my to-do list. I figured that between the comments I saw and Steve’s documentation, the method worked as advertised.
The topic came up again recently when a client wanted to know the available options for migrating from AIX 5.2 running on a 550 to a 9117-MMA. Since AIX 5.2 doesn’t run on the 9117-MMA, we needed to figure out how to best handle the migration, which would also include an operating system upgrade.
There are multiple options for doing this; I only cite two here. The first, which is explained on the InfoCenter site, is to use an available internal disk on the 550 and perform an alt disk install. Once the install completes, you reboot and take the mksysb from the updated OS and use it to load the newly upgraded OS onto the new hardware. After the mksysb completes, boot the source system back into the 5.2 environment using the original rootvg disk. A downside to this method is that it requires an outage when booting into the new environment to take the mksysb. The amount of change and the downtime makes this method unacceptable for some environments.
An alternative is to do a regular OS upgrade on the original machine, take the OS to a supported version and then take a mksysb of the new OS and move it to the new hardware. A downside here is if something goes wrong with the upgrade, your backout plan is to resort to a backup tape or NIM reinstall using a mksysb file. I prefer to leave the source machine intact to simplify my backout plan–just run the workload on that source server until the cutover. If there’s a problem after the cutover, I move back to the original machine.
We chose a mksysb migration for our migration from the 550 to the MMA. Since I hadn’t tried it before, I thought I’d test it out in the lab first. I took an AIX 5.3 mksysb, performed a mksysb migration on it and took it to AIX 6.1. I followed the directions in the “NIM from A to Z in AIX 5L” Redbooks publication, pages 205-216. In the Redbooks example, the authors create a file called /other_res/bid.np.hd0.mkmig. The file I created was called /home/test/aix53.custom. Here’s how it looked:
control_flow:
INSTALL_METHOD = migrate
PROMPT = no
EXISTING_SYSTEM_OVERWRITE = yes
RECOVER_DEVICES = no
MKSYSB_MIGRATION_DEVICE = network
CONSOLE = Default
target_disk_data:
PVID =
PHYSICAL_LOCATION =
CONNECTION =
LOCATION =
SIZE_MB =
HDISKNAME = hdisk0
locale:
BOSINST_LANG =
CULTURAL_CONVENTION =
MESSAGES =
KEYBOARD =
I ran:
/usr/lpp/bosinst/bicheck /home/test/aix53.custom
When it came back clean, I went through these smitty menu options to create the new bosinst.data file as a resource:
Smitty nim / Perform NIM Administration Tasks / Manage resources /
Define a resource
I selected:
bosinst_data = config file used during base system installation
Then I came up with a name for the resource, the server it was located on (the master in my case) and the location of the file (/home/test/aix53.custom).
After that resource was defined, I reselected those menu options to define my 5.3 mksysb file as a resource:
Smitty nim / Perform NIM Administration Tasks / Manage resources /
Define a resource
This time I picked:
mksysb = a mksysb image
I gave it a resource name, the server (master) and the location of the file (/home/test/aix53.mksysb).
Then I went to back to smitty:
Smitty nim / NIM Administration Tasks / Manage machines / Manage network install
resource allocation / Allocate network install resources
I chose the NIM client I was going to target. Then I selected the mksysb resource I’d previously created.
Lastly, I prepared my client for the install. Back to the smitty menu:
Smitty nim / Perform NIM Software Installation and Maintenance Tasks /
Install and Update Software / Install the Base Operating System on Standalone Clients
I picked my client, and selected:
rte – Install from installation images
I selected my lppsource and my spot as if I were doing a normal rte base installation. Then I selected the bosinst.data file that I created earlier as a resource in this field:
BOSINST_DATA to use during installation
I also made sure to accept licenses where appropriate, and set the “Initiate Reboot and Installation Now” prompt to no.
At this point, I was able to kick off my NIM install from my client as I always would. In this case, I happened upon a bug in AIX 6.1. It would get partway through the install, then puke and die, leaving me in single-user mode on my client LPAR. At the time I wondered whether this method was ready for prime time. Turns out it is indeed. I contacted IBM Support and learned that I was running a slightly older AIX 6.1 version that didn’t include a needed fix. IBM gave me a manual work-around that involved editing my image.data file to add information about the /admin directory. Once I did that, it worked exactly as advertised. (Note: There is now an APAR that’s included in the latest fixes that resolves this issue.)
When I was done, my system was running AIX 6.1 exactly as it would have been had I migrated it on the source machine and then cloned it to my target machine. As I stated in my original post, this
method is particularly handy for migrating old, unsupported operating systems from old, unsupported hardware onto our new POWER6 gear.