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© 2013 SAP AG 1

New Features of SAP ClusterResource Type DLL for MicrosoftFailover Cluster

Applies to:

SAP NetWeaver ’04 and higher running in a Microsoft Failover Cluster environment.

Summary

This document describes the changes and new features included in the SAP Cluster Resource Type DLL(saprc.dll and saprcex.dll).

Author: Bernd Kuespert

Company: SAP AGCreated on: 10 October 2012

Updated on: 13 June 2013

Author Bio

Bernd Kuespert is working in the Microsoft Platforms Department as a Senior Developer for SAP AG and isresponsible for Update and Upgrade Procedures on Windows and Windows Failover Clustering for SAPsystems based on SAP NetWeaver.



New Features of SAP Cluster Resource Type DLL for Microsoft Failover Cluster


© 2013 SAP AG 2

Table of Contents

The SAP Cluster Resource DLL ......................................................................................................................... 3

Changes in SAP Cluster Resource Type DLL .................................................................................................... 3

Prerequisites ................................................................................................................................................... 3

Introducing the Maintenance Mode Flag ......................................................................................................... 3

Steps to Perform Before an Upgrade ........................................................................................................................... 4

Steps to Perform After an Upgrade .............................................................................................................................. 4

Check the Availability of the Maintenance Flag............................................................................................................ 4

Communication Interface ................................................................................................................................ 5

Related Content .................................................................................................................................................. 5

Copyright............................................................................................................................................................. 6





© 2013 SAP AG 3

The SAP Cluster Resource DLL

In a Microsoft Failover Cluster, every third-party Resource Type implementation has to use its own set ofresource DLLs including the coding to properly interoperate with the cluster service. After the DLLs havebeen registered in the Microsoft Failover Cluster, the Resource Control Manager and the Resource HostSubsystem (RHS) that are part of the cluster service can maintain and monitor the state of the resource(online, offline, failed, etc.) and execute some actions (move, failover, and failback).

A Resource DLL provides the important IsAlive and LooksAlive checks, which are both executed by the

Resource Monitor .

The IsAlive function checks by default every 60 seconds (configurable through the isAlivePollInterval property), whether the resource works properly.

The LooksAlive function works more precisely than the IsAlive function. The LooksAlive function checks bydefault every 5 seconds (configurable through the LooksAlivePollInterval property), whether a resource isavailable for use.

The timeout value specifies how many seconds the Failover Cluster Service waits until it acknowledges thatthe resource failed.

In addition, resources have common properties, owned by every instance of a cluster object and specialprivate properties, owned by an individual instance of a cluster object.

Changes in SAP Cluster Resource Type DLL

The new version of the SAP Cluster Resource Type DLL contains the following enhancements and fixes. Fora description of how to update the SAP Resource Type DLL, see SAP Knowledgebase Article 1596496.

The new version of the SAP Resource Type DLL is downward-compatible to older SAP Kernel versions.

Prerequisites

To be able to use the new features, you have to install an SAP Kernel with the following minimum patchlevel:

Kernel Version Patch level

SAP Kernel 6.40 for SAP Web AS 6.40 PL 387

SAP Kernel 7.20 for SAP NetWeaver 7.x PL 102

For more information about how to install a new SAP Kernel, see SAP Note 1636252.

Introducing the Maintenance Mode Flag

So far it was mandatory to misconfigure the SAP Instance Resource with a non-existing SAP system numberto prevent an unwanted failover of the SAP cluster group during an upgrade as described in the upgradedocumentation.

With the new version of the SAP Cluster Resource DLL, this misconfiguration is no longer required. You onlyhave to set MaintenanceMode to 1. You can set or unset the flag as a private property of an SAP Instance Resource by using the and the Properties menu of an SAP Instance Resource in the Failover ClusterManager, the command line tool cluster.exe, or PowerShell (as of Windows Server 2008 R2).

On Windows Server 2008 R2, the PowerShell cluster commands are only available after the import of themodule FailoverClusters (import-module failoverclusters). To get an overview of all cmdlets of themodule, you can use the command: get-command -module failoverclusters.

https://service.sap.com/sap/support/notes/1596496


http://service.sap.com/sap/support/notes/1636252









© 2013 SAP AG 4

Be aware that when there is more than one Resource of resource type SAP Resource in a cluster group, youmust set the property of every single resource.

If the Maintenance Mode flag of the SAP Instance Resource is set, the SAP MMC or sapcontrol no longeruse the cluster interface when starting and stopping an SAP instance.

Steps to Perform Before an Upgrade

You have to perform the following steps on the Failover Cluster before starting an update or upgrade of anSAP system:

1. Stop the Instance and the Service Resource.

Using cluster.exe:

cluster res "SAP <SID> <SYS#> Instance" /offline

cluster res "SAP <SID> <SYS#> Service" /offline

Using PowerShell

stop-clusterresource “SAP <SID> <SYS#> Instance”

stop-clusterresource “SAP <SID> <SYS#> Service”

2. Set the Maintenance Mode in the Properties of the SAP Instance Resource:

Using cluster.exe:

cluster res "SAP <SID> <SYS#> Instance" /priv MaintenanceMode=1

Using PowerShell:

Get-ClusterResource "SAP <SID> <SYS#> Instance" | set-clusterparameter

MaintenanceMode –value 1

3. Leave both SAP Cluster Resources offline. Do not start them again at this point in time. Otherwisethe cluster fails over in the event of a restart of the SAP Instance resource.

Steps to Perform After an Upgrade

After the upgrade, disable Maintenance Mode and start both SAP Cluster Resources (Service andInstance Resource) again.

Using cluster.exe:

cluster res "SAP <SID> <SYS#> Instance" /priv MaintenanceMode=0

cluster res "SAP <SID> <SYS#> Service" /online

cluster res "SAP <SID> <SYS#> Instance" /online

Using PowerShell:

Get-ClusterResource "SAP <SID> <SYS#> Instance" | set-clusterparameter

MaintenanceMode –value 0

start-clusterresource “SAP <SID> <SYS#> Service”

start-clusterresource “SAP <SID> <SYS#> Instance”

Check the Availability of the Maintenance Flag

Check whether the SAP Instance Resource supports the Maintenance Flag.

Using cluster.exe:

Cluster.exe resource “SAP <SID> <SYS#> Instance” /priv

Using PowerShell:





© 2013 SAP AG 5

Get-ClusterResource "SAP <SID> <SYS#> Instance" | Get-ClusterParameter

The list of private properties returned should include the MaintenanceMode property (output of

cluster.exe):

Listing private properties for 'SAP <SID> <SYS#> Instance':

T Resource Name Value

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

S SAP OQ7 00 Instance SAPSystemName <SID>

S SAP OQ7 00 Instance SAPSystem <SYS#>

D SAP OQ7 00 Instance SAPPendingWait 300 (0x12c)

D SAP OQ7 00 Instance AccepableYellowTime 300 (0x12c)

D SAP OQ7 00 Instance WaitBeforePoll 10 (0xa)

D SAP OQ7 00 Instance Trace 0 (0x0)

D SAP OQ7 00 Instance MinGoodProcesses 1 (0x1)

D SAP OQ7 00 Instance EnableInterfaceCaching 0 (0x0)

D SAP OQ7 00 Instance ServiceControl 1 (0x1)

S SAP OQ7 00 Instance MaintenanceMode 0

Communication Interface

We had several issues in the past where already existing cluster resources faced a failover during theinstallation of other SAP components (SAP MMC, second or third instance in a cluster). The reason for thiswas that every time a SAP start service is registered, the DCOM type library is unregistered, replaced, andregistered again.

When the resource monitor performs an IsAlive or LooksAlive check on the resource during this action, theDCOM connect fails and the resource monitor initiates a failover of the SAP Cluster Group.

Switching the communication interface between SAP service and resource monitor from DCOM to SOAPbased on named pipes prevents this behavior.

Related Content

SAP KBA 1596496 - How to update the SAP Resource Type DLLs for the Cluster Resource Monitor

SAP Note 1654694 - Processes are not stopped during failover of the SAP group

SAP Note 1636252 - Installing a 7.20 kernel in SAP Web AS 7.00/7.01/7.10/7.11

















© 2013 SAP AG 6

Copyright

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