SAP Basis Tech Supports

Symptom

Avoid downtime for hardware/firmware maintenance
Other terms

AIX LPM Live Partition Mobility Migration POWER6 Linux
Reason and Prerequisites

IBM System p6 servers based on the IBM POWER6 processor Firmware version EM320_031 or higher
Hardware Management Console (HMC) Version V7R320 (plus fix MH01062) or higher
AIX 5.3 required level: 5.3.7.1 or higher
AIX 6.1 required level: 6.1.0.1 or higher
VIOS required level: 1.5.1.1-FP-10.1 (plus APAR IZ08861) or higher
Red Hat Enterprise Linux: RHEL 5.1 + fix RHSA-2007:0993-13 or higher
SUSE Linux Enterprise Server: SLES 10 SP1 plus security update 37043bf4ccbd3272d8b7e37b6b76768b or higher
Please check the following web site for latest updates and links to download locations:
http://www14.software.ibm.com/webapp/set2/sas/f/pm/component.html

Solution

Live Partition Mobility (LPM) has been successfully tested by IBM within SAP environments. Any problems related to LPM technology that arise while using LPM with SAP systems will be handled by IBM.

Introduction

Live Partition Mobility allows you to move running AIX and Linux partitions including their hosted SAP and application database services from one physical server to another without disrupting the availability of those services. With this feature you can eliminate the need to stop applications to re-balance the total system landscape to react on changes in capacity needs, or to perform system maintenance or upgrades.
There are no SAP code changes required to use this feature.
A live partition migration will duplicate the exact same environment of the current partition (memory resources, entitled capacity, number of virtual processors, etc) on the destination server. The migration will stop if these required resources aren’t available during a pre-migration validation check. Therefore the application’s compute environment will look mostly the same after a migration. However the underlying processor type or frequency may change as a result of a migration. This might cause some performance variations or have an impact on performance analysis, accounting, and capacity planning tools.
A migration transfers the complete system environment including memory content, processor states, attached devices, and connected users. During the migration process there is a very short period of time where processing is suspended on the source server, before the partition is resumed on the destination server. To an end-user this might look as a temporary increase in response time (one would see the hour glass), but a running transaction will continue seamlessly after the switch.

Database Support with LPM
DB2

The required minimum software levels are:
DB2 V9.1 FP4DB2 V9.5

MaxDB

The required minimum software levels are:
MaxDB 7.6MaxDB 7.7

For specific MaxDB restrictions in virtualized systems please read:
SAP note: 1142243 “MaxDB release for virtual systems”

Oracle

The required minimum software levels are:
Oracle DB 10gR2 (10.2.0.4) – Single Instance only, no RACAIX 5.3 TL8 SP4, orAIX 6.1 TL2 SP3

Please note that Live Partition Mobility is certified for single
Oracle database instances only, Oracle RAC is not yet supported. Formal testing with Oracle RAC is still ongoing and support will be
announced at a later date.

SAP License Keys

One issue a system administrator needs to be aware of is that the HW key will change after a completed migration. This is relevant mostly for the central instance (message server) only, as it reads the HW key during system startup and then uses this key for the license check during user logon. The key is buffered, so there won’t be any problem immediately after a migration. However a subsequent restart of the central instance would read the new HW key and could then cause the license check to fail.
To prevent this problem, one should apply for and install a license key for the destination server in advance (as you would do in a HA cluster).The HW key is the same for all partitions running on a server, so if you have already have a running SAP system on another partition on the destination server, then you can use the HW key of that system to apply for the new license key on the SAP service portal.
If you don’t have a SAP system on the destination server yet, then you could just copy the saplicense binary of one SAP system to any partition running on the destination server and use “saplicense -get” to retrieve the HW key.
If you run any other 3rd party applications you should check in advance whether they use a license model that depends on the HW key and establish a procedure to ensure that they continue to operate after a live partition migration.

LDAP Client Setup

In case you are using the AIX LDAP client to manage OS user IDs, you need to be aware that certain releases use a system specific encryption format for the LDAP server bind password. This could lead to the same situation as with SAP license keys. OS user ID authentication would continue to work after a live partition migration, however it would fail after a subsequent restart of the partition.
The password encryption format was changed to address this problem and you should verify that the following APARs are installed on your partition:
AIX 5.3 IZ06835
AIX 6.1 IZ06829
After that you should rerun the “mksecldap -c” to configure your LDAP client again, so that the bind password is stored in the LDAP configuration file using the new encryption format.

AIX Network Installation Management (NIM)

For customers using AIX NIM to manage the OS software levels, there is a potential problem if you initiate a NIM operation on a client after a migration. The CPU ID of a NIM client is stored in the NIM database so that the master can perform a check that NIM client requests are coming from the same machine that was originally registered as a client. This id changes with a migration and subsequent NIM client requests would fail. As a workaround the client CPU ID check can be disabled using the fastpath “smitty nim_cpuid_validate”.
More details about this attribute can be found here:
http://publib.boulder.ibm.com/infocenter/systems/index.jsp?topic=/com.ibm.aix.install/doc/insgdrf/addl_disable_client.htm& tocNode=int_8662
This check is only relevant for client initiated NIM operations. NIM operations are typically initiated by the NIM server, in that case the physical processor validation never happens.

Supporting Documentation

Please refer to the following documentation for a detailed description of the Live Partition Mobility feature, requirements and setup:
Advanced Power Virtualization Operations Guide:
https://www-01.ibm.com/servers/resourcelink/lib03030.nsf/pagesByDocid/0D 54AD0F9AC25A39852572E3002EC8EE?OpenDocument&pathID=132
Redbook:
http://www.redbooks.ibm.com/abstracts/sg247460.html?Open