AIX, LPM & Partition ID sorcery! Why does AIX report that my partition ID has changed after LPM when it hasn't?

AIX, LPM & Partition ID sorcery! Why does AIX report that my partition ID has changed after LPM when it hasn't?

 

I LPM'ed an AIX LPAR from Frame A to Frame B. The LPAR id before the LPM was 99 and after the LPM it's still 99. And the system id has changed, as expected. Good.

Before migration.

root@lpar1 / # uname -L

99 lpar1

root@lpar1 / # lsattr -El sys0 -a systemid

systemid IBM,017268B60 Hardware system identifier False

After migration.

root@lpar1 / # uname -L

99 lpar1

root@lpar1 / # lsattr -El sys0 -a systemid

systemid IBM,0157F5B16 Hardware system identifier False

Great, that's exactly what I wanted.

Hang on a minute! What kind of sorcery is this?!

root@lpar1 / # errpt | grep sys

60AFC9E5   0405132517 I O sys0           Partition ID changed since last boot.

root@lpar1 / # errpt -aN sys0

---------------------------------------------------------------------------

LABEL:          PARTID_CHANGE

IDENTIFIER:     60AFC9E5

Date/Time:       Wed Apr  5 13:25:53 EET 2017

Sequence Number: 81372

Machine Id:      000157F5B16

Node Id:         lpar1

Class:           O

Type:            INFO

WPAR:            Global

Resource Name:   sys0

Description

Partition ID changed since last boot.

Whaddaya mean my partiton ID changed since last boot?! It hasn't! I know this for a fact! Look at the uname output above!!

Well, I'm 100% correct, the partition id HAS NOT CHANGED! But the system id has....and this is the cause of the "informational" message in the AIX error report.

AIX uses the output from 'uname -f' to detect if the system AND/OR partition id have changed since last boot.

So, in my case, the partition id (99 dec/63 hex) did not change but (as you'd expect with LPM) the system id (shown in hex below) has changed, hence the message "Partition ID changed since last boot".

Before LPM.

root@lpar1 / # uname -f

80000BA02DC00063

After LPM.

root@lpar1 / # uname -f

800016B466F00063

From the uname man page:

-F Displays a system identification string comprised of hexadecimal characters. This identification string is the same for all partitions on a particular system.

                                                     

-f Similar to the F flag, except that the partition number is also used in the calculation of this string. The resulting identification string is unique for each partition on a particular system.

So, no problem here. Nothing to see, nothing to do. Move along!