High MTBF. Low MTTR. Windows Reliability Improvements. Backup and Recovery. Certification and Validation of Hardware. Hardware Sizing. Disk Layouts. Fibre Channel Configurations. Network Configurations. Installation and Verification. General Overview of the Installation Process. Setting Up Security. Hardware Configuration and Installation. Windows NT Installation. Basic Windows NT Tuning. Microsoft Cluster Server Installation. MSCS Verification.
Create the Installation User Account. SAP Verification. DBMS Verification. Backbone Configuration. SAP Cluster Verification. Configuring a Remote Shell. Installation Using Oracle. Preliminary Work. Oracle Installation. SAP Cluster Conversion. Oracle Cluster Conversion. Installation Using DB. DB2 Installation. Install the Central Instance and Database Instance. DB2 Cluster Conversion. Convert the Database to Cluster Operation.
Install the Cluster Conversion Tool. Removal of Unused Resources. Backbone Network. Benefits of the Backbone Configuration. Advanced Windows NT Tuning. General SAP Tuning. Database Tuning. Verifying the Installation. How to Troubleshoot the System at the End of the Installation. Log Files. Accounts and Users. Appendix A: Special Notices. Appendix B: Related Publications. IBM Redbooks. IBM Redbooks Collections. Related Web Sites. Downloadable Documents.
OSS Notes. Knowledge Base Articles. Other Publications. List Of Abbreviations. IBM Redbooks Evaluation. Copyright Date. Target Audience. Dewey Decimal. Dewey Edition. Better World Books betterworldbooks A standby system is a redundant cluster node that takes over the processes if the primary cluster server fails.
This is referred to as a "failover" and is performed automatically by cluster software. There can be several standby cluster nodes. The amount is only limited by the capabilities of the cluster software. For example, the Microsoft Cluster Service provides up to 8 server nodes, which means 7 standby nodes as a maximum. A "hot standby" means that the processes run on the standby node also, which means that in case of a failure the cluster resource is running already and does not need to be started on the standby system.
A "cold standby" means that in case of a failover the clustered resource needs to be started on the standby system which means that a short downtime during the failover occurs.
The SAP Central Services Instance is usually implemented as a "cold standby" system due to the fact that SCS is a light component and does not need a long time for startup. An active-active cluster consists of two independent server nodes at a minimum. The workload within a cluster resource is shared between the server nodes. If a cluster node crashes the processes are resumed by the remaining cluster nodes. An active-active cluster configuration means that a cluster resource is active on all cluster nodes.
The aim of an active-active cluster is not only to provide high availability system but to distribute the workload between the cluster nodes. Applications with a very high workload like databases benefit from an active-active setup. Therefore the SCS is implemented as an active-passive cluster resource.
The software creates a virtual host that owns a virtual hostname, virtual disk, and so on. Which node currently owns or runs a resource is managed by the cluster software. The term "shared nothing" and "shared all" specifies a type of architecture within an active-active cluster. In a "shared all" environment the different cluster nodes that run the same service shares a data partition and accesses the data concurrently. These options have to be supported by the cluster software.
For example, MSCS does not support the "shared all" option. A SPOF can be hardware or a software component. Be aware that it is possible to introduce additional SPOFs through configuration and programming, by adding critical, non redundant components yourself.
These must be identified through an analysis and either be eliminated or covered by failover services. SAP supports the installation of High Available systems with several aspects. In addition, it is important to analyze your system to be sure that no single points of failure are overseen, as it is possible to configure your system in that way or to write custom software that behaves that way.
We recommend to engage experienced consultants on this analysis. In general SAP systems are set up High Available through their technology components, which are the application servers. However, it is also responsibility of a running program to not introduce additional singel points of failure. At SAP this is ensured through extensive quality management, for custom development this should be carefully considered.
SAP does not support heterogeneous HA cluster environments at the moment officially. However, preparations for an official support of this type of setup are currently evaluated. First of all, Geo-Clustering Microsofts name for it is geographically dispersed Clusters is no special product from Microsoft, it's just a special setup of the normal MSCS or to be more correct, Microsoft Server Cluster configuration of Windows Server The standard configuration of a two node MSCS cluster consists of two cluster nodes and a shared storage.
Do we have to set any additional profile parameters on the App Server or CI side to overcome this issue? I worked for a customer and I was recording my experiences during a project. I'm afraid that I have been away from the topic too long and I don't have any helpful hints for you.
But to your error - I can definetely tell you that this is NOT normal. Skip to Content. Thomas Jung. May 31, 1 minute read. The Layout We opted to go with a two node cluster layout.
Alert Moderator. Alerting is not available for unauthorized users. Assigned Tags. Similar Blog Posts. Related Questions. You must be Logged on to comment or reply to a post. Former Member. Hi,Also IGS problem is. Like 0 Share. Right click and copy the link to share this comment. It did work when we were applying later support packages SP12 to our installation. Even with this switch - in my testing I still had one entry just one field with Message Server Host in the configuration that still had hostname instead of virtual host that I had to update manually.
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