Experiences with SAP in-place upgrades

Many of you probably have already seen messages that in-place upgrades of the Windows O/S with third-party apps require special attention. Upgrading from Windows Server 2003 to Windows Server 2008 or from Windows Server 2008 to Windows Server 2008 R2 will result in a message like the following:

Before continuing with the upgrade, make sure software vendors support your software on Windows Server 2008. Follow their software specific recommendations before and after the upgrade. To verify software compatibility on the Windows Server Catalog and to download tools and documentation, go to http://go.microsoft.com/fwlink/?LinkID=85172.

Important: If software isn’t supported on Windows Server 2008, or if the software vendor does not support software that is installed during the upgrade of the operating system, uninstall that software before you upgrade. If you do not uninstall the software, your system will be unsupported, the software might not work, and software settings or other information might be lost.

Since SAP did not perform testing of the O/S upgrade, there is currently no information or support statement from SAP on this available. As I did recently a couple of tests on upgrading Windows, I wanted to share some best practice with you.

Before starting any upgrade, typical IT Best practice like creating backups – with a virtualized installation, possibly a snapshot – is of course mandatory. Also, the question if the current SAP version installed is supported on my target O/S – today that’s Windows Server 2008 – has to be resolved. This information is found at the SAP Platform Availability Matrix (PAM) at SAP’s Service Marketplace. Mainstream ERP applications which run on Netweaver 7.0 are supported on W2K8.

One important question for the upgrade is the type of Database used. If SQL Server is installed, it’s supported by Microsoft for in-place upgrades. For any other type of DB, one would need to verify with the DB vendor. In my upgrade tests, I had a Web Application Server 7.0 with SQL Server on Windows Server 2003; therefore I had no problem with the DB.

The support statement above would now ask me to uninstall my SAP Web Application Server instance before the upgrade and re-install this instance after the upgrade has finished. I did however perform the in-place upgrade to see what problems would come up. I did this in two steps, form W2K3 to W2K8 and from W2K8 to W2K8 R2 and for each type ABAP and Java.

The upgrade process itself went very smooth, besides the message above everything worked fine. In both cases on the ABAP side, the SAP instance did not start immediately after the upgrade. I found some errors in the traces indicating that the Message server of the SAP instance was unable to determine at which port it should listen. The SAP port definition is usually in the file C:\Windows\System32\drivers\etc\services. I found that this file was replaced with a new version during the upgrade. After restoring the SAP specific entries into this file, the instance started and worked without any problem. Basically the same happened on the Java side. Here also the port definitions in the services file have been overwritten by a new file. The only difference here was that tracing the effect in the logs was a bit harder. However, after restoring the SAP specific port info’s into the services file, everything worked also here again.

It’s clear that this best practice cannot be considered to be a supported process but knowing the potential problems may help to avoid some pitfalls and save time. I always would suggest to keep a private backup of the services file and restore the SAP service port config after upgrading. In all cases, this has helped to get my systems to work again very fast.

- Josef