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

Creation of Replication Instance
This section describes how to add Enqueue Replication Services (ERS) to a system that has SAP
kernel 4.6, 6.x or 7.0 ASCS and/or SCS instances. The section can be skipped for SAP kernel
version 7.10 and later. Use the installation routines for ERS instances as provided by the SAP
installer instead.
The ASCS (ABAP) or SCS (JAVA) instance will be accompanied with an ERS instance that
permanently keeps a mirror of the [A]SCS internal state and memory. As a result, no information
gets lost due to failing SAP System Central Services if the SGeSAP package that includes [A]SCS
fails over to the node that runs ERS during runtime.
NOTE: If both SCS and ASCS are intended to take advantage of Replicated Enqueue, then the
following steps need to be executed twice.
Replicated Enqueue Conversion: RE070
Create a new mountpoint.
su - <sid>adm
mkdir /usr/sap/<SID>/ERS<INSTNR>
Replicated Enqueue Conversion: RE080
A volume group needs to be created for the ERS 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 be able to run the Replicated Enqueue. For the
volume group, one logical volume should get configured.
Mount the new logical volume to the mountpoint created in RE070.
NOTE: The <INSTNR> of the ERS has to be different from the instance number of the ASCS
and SCS.
Replicated Enqueue Conversion: RE090
Create instance subdirectories in the mounted logical volume.
They will be switched between the cluster nodes later.
su - <sid>adm
cd /usr/sap/<SID>/ERS<INSTNR>
mkdir data log exe work profile
Starting with SAP kernel 7.0, the following subdirectory structure also needs to be created:
mkdir -p exe/servicehttp/sapmc
Replicated Enqueue Conversion: RE095
A couple of required SAP executables should be copied from the central executable directory
/sapmnt/<SID>/exe to the instance executable
directory/usr/sap/<SID>/ERS<INSTNR>/exe.
For SAP kernel 6.40, the list includes:
enqt, enrepserver, ensmon, libicudata.so.30, libicui18n.so.30,
libicuuc.so.30, libsapu16_mt.so, libsapu16.so, librfcum.so, sapcpe, and
sapstart.
For some releases, the shared library file extension .so is replaced by .sl. Apart from this, the
procedure remains the same. Copy these files and add a file named ers.lst in the instance
executable directory. The ers.lst should include the following lines:
enqt
enrepserver
ensmon
libicudata.so.30
libicui18n.so.30
SAP Preparation 47