Managing Serviceguard Extension for SAP, December 2007

Planning the Storage Layout
SAP Instance Storage Considerations
Chapter 262
Option 3: SGeSAP CFS Cluster
SGeSAP supports the use of HP Serviceguard Cluster File System for
concurrent shared access. CFS is available with selected HP
Serviceguard Storage Management Suite bundles. CFS replaces NFS
technology for all SAP related file systems. All related instances need to
run on cluster nodes to have access to the shared files.
SAP related file systems that reside on CFS are accessible from all nodes
in the cluster. Concurrent reads or writes are handled by the CFS layer.
Each required CFS disk group and each required CFS mount point
requires a Serviceguard multi-node package. SGeSAP packages are
Serviceguard single-node packages. Thus, a package can not combine
SGeSAP and CFS related functionality.
Common Directories that are Kept Local
Most common file systems reside on CFS, but there are some directories
and files that are kept local on each node of the cluster:
• /etc/cmcluster — the directory in which Serviceguard keeps its
configuration files and the node specific package runtime directories.
• /home/<SID>adm — the home directory of the SAP system
administrator with node specific startup log files.
• /usr/sap/tmp — the directory in which the SAP operating system
collector keeps monitoring data of the local operating system.
• /usr/sap/<SID>/SYS/exe/run — optional directory for usage with
sapcpe, i.e. a local copy of executables.
• Depending on database vendor and version, it might in addition be
required to keep local database client software. Details can be found
in the database sections below.
Content of the local group of directories must be synchronized manually
between all nodes of the cluster. An exception is the optional local
directory for SAP executables /usr/sap/<SID>/SYS/exe/run. It gets
automatically synchronized as part of every instance startup and
shutdown operation. A symbolic link called
/usr/sap/<SID>/SYS/exe/ctrun needs to be created to access the
centrally shared location.