Managing Serviceguard Extension for SAP Version B.05.10, September 2010

each subnet. The LUNs need to have the size that is required for a SAP Instance directory of the
targeted kernel release.
Splitting an ABAP Central Instance
The SPOFs of the DVEBMGS<INSTNR> instance will be isolated in a new instance called ABAP
System Central Services Instance ASCS<INSTNR>. This instance will replace DVEBMGS<INSTNR>
for the ci package type. The remaining parts of the Central Instance can be configured as Dialog
Instance D<INSTNR_2>. The ASCS Instance should only be started and stopped with the cluster
package startup and halt commands instead of using manual shell operations.
NOTE: The Dialog Instance D<INSTNR_2> that results from the conversion also represents
one or more Single Points of Failure for many scenarios. In these cases, D<INSTNR_2> should
also be clustered with SGeSAP. It is not even unusual to combine ASCS<INSTNR> and
D<INSTNR_2> in a single SGeSAP package. It makes sense, even though the resulting package
contains the same components like a traditional package for DVEBMGS<INSTNR> would. Seamless
failover with Replicated Enqueue cannot be achieved without splitting up DVEBMGS<INSTNR>
into two instances.
Logon as root to the server where the Central Instance DVEBMGS<INSTNR> was installed.
Replicated Enqueue Conversion: RE010
Create a new mountpoint:
su - <sid>adm
mkdir /usr/sap/<SID>/ASCS<INSTNR>
Replicated Enqueue Conversion: RE020
A volume group needs to be created for the ASCS instance.
The physical device(s) should be created as LUN(s) on shared storage. Storage connectivity is
required from all nodes of the cluster that should run the ASCS. For the volume group, one
logical volume should get configured. For the required size, refer to the capacity consumption
of /usr/sap/<SID>/DVEBMGS<INSTNR>. This should provide a conservative upper limit that
leaves reasonable headroom.
Mount the new logical volume to the mountpoint created in RE010.
Replicated Enqueue Conversion: RE030
Create instance subdirectories in the mounted logical volume.
At a later time, these will be switched between the cluster nodes.
su - <sid>adm
cd /usr/sap/<SID>/ASCS<INSTNR>
mkdir data log sec work
Replicated Enqueue Conversion: RE040
If the used SAP kernel has a release older than 6.40...
Download the executables for the Standalone Enqueue server from the SAP Service Marketplace
and copy them to /sapmnt/<SID>/exe.
There should be at least three files that are added/replaced: enserver, enrepserver, and
ensmon.
Make sure these files are part of the sapcpe mechanism for local executable creation (see chapter
2).
This step will create a version mix for the executables. The Standalone Enqueue executables get
taken from the 6.40 kernel. Special caution has to be taken to not replace them with older releases
later on. This might happen by accident when kernel patches get applied.
Replicated Enqueue Conversion: RE050
44 Step-by-Step Cluster Conversion