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

All nodes in the cluster mount the NFS exported files systems as NFS clients. Mount point for
the NFS client file system is /home/mdmuser. Each of the MDM server (mds, mdss and mdis)
components will use it's own directory (e.g.: /home/mdmuser/mds, /home/mdmuser/mdss,
/home/mdmuser/mdis) within /home/mdmuser.
Should the NFS server node fail - then the storage volume will be relocated to another cluster
node, which then will take over the NFS server part.
NOTE: The advantage of the NFS server/client approach from a system management viewpoint
is only one copy of all the MDM server files have to be kept and maintained on the cluster instead
of creating and distributing copies to each cluster node. Regardless of on which node any of the
MDM server components are running in the cluster - the MDM server files are always available
in the/home/mdmuser directory.
The disadvantage: I/O performance might become a bottleneck. Should IO performance become
an issue then it would become necessary to split and to create local/relocatable file systems for
/home/mdmuser/mds, /home/mdmuser/mdss,/home/mdmuser/mdis.
/opt/MDM
The /opt/MDM mount point is used for storing the binaries of the MDM servers. These are static
files installed once during the installation. In this specific cluster configuration each cluster node
had it's own copy of the /opt/MDM file system. The/opt/MDM only contains a few files and
because of it's small size, a separate storage volume / mount point was not created but instead
kept in the existing /opt directory. The disadvantage here is a copy has to be maintained (for
each software installation) on each cluster member. From a system management an alternative
approach would be to configure /opt/MDM as an NFS file system.
Single or Multiple MDM Serviceguard Package Configurations
MDM with SGeSAP can be configured to run either as a "Single" Serviceguard package (ONE
package) OR as "Multiple" Serviceguard packages (FOUR+ONE).
Single MDM Serviceguard Package (ONE)
• In the case of "Single" MDM Serviceguard package all four MDM components (mdb mds
mdis mdss) are always started and stopped together on "one" cluster node - the node on
which the Serviceguard package itself is started or stopped on. All four MDM components
are combined or grouped together. This is also is reflected in the name for this Serviceguard
package name called mgroupMDM.
• The naming convention for the Serviceguard packages is: mgroupID - the string "mgroup"
stands for mdm grouped components and is required; the string ID is used as a placeholder
for a xx System ID and can be set to any value.
• The mgroupMDM package contains code for dependency checks: it will ensure that the MDM
components are started and stopped in the correct order: mdb -> mds -> mdis -> mdss - and
in the reverse order for stop.
• The advantage of the Single MDM Serviceguard package is a simpler setup - less steps are
involved in setting up and running the configuration - but with the limitation that all four
MDM server components always have to run together on the same cluster node.
Multiple MDM Serviceguard packages (FOUR+ONE)
• In the case of "Multiple" MDM Serviceguard packages each of the four MDM component (mdb,
mds, mdis and mdss) is configured and run in a separate (mdbMDM, mdsMDM, mdssMDM,
mdisMDM) Serviceguard package. So in the case of a four node cluster each MDM Serviceguard
132 SAP Master Data Management (MDM)