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

2 Planning the Storage Layout
Volume managers are tools that let you create units of disk storage known as storage groups.
Storage groups contain logical volumes for use on single systems and in high availability clusters.
In Serviceguard clusters, package control scripts activate storage groups. Two volume managers
can be used with Serviceguard: the standard Logical Volume Manager (LVM) of HP-UX and the
Veritas Volume Manager (VxVM). SGeSAP can be used with both volume managers. The following
steps describe two standard setups for the LVM volume manager. VxVM setups can be configured
accordingly. A third storage layout option describes a Cluster File System configuration for
SGeSAP. In this case, VxVM must be used and all Application Servers need to run on cluster
nodes. Chapter three explores the concepts and details the implementation steps discussed in
this chapter.
Database storage layouts for usage with parallel databases are only briefly described for Oracle
Real Application Clusters. Detailed configuration steps for parallel database technologies are
not covered in this manual. Additional information about SGeSAP and parallel databases is
being released as whitepapers from HP. Refer to the Additional Reading section of the relevant
SGeSAP release notes to verify the availability of whitepapers in this area.
This chapter discusses disk layout for clustered SAP components and database components of
several vendors on a conception level. It is divided into two main sections:
• SAP Instance Storage Considerations
• Database Instance Storage Considerations
SAP Instance Storage Considerations
In general, it is important to stay as close as possible to the original layout intended by SAP. But,
certain cluster-specific considerations might suggest a slightly different approach. SGeSAP
supports various combinations of providing shared access to file systems in the cluster.
The possible storage layout and file system configuration options include:
Table 2-1 Option descriptions
DescriptionOption:
Optimized to provide maximum flexibility. Following the recommendations given
below allows for expansion of existing clusters without limitations caused by the
cluster. Another important design goal of SGeSAP option 1 is that a redesign of the
storage layout is not imperative when adding additional SAP components later on.
Effective change management is an important aspect for production environments.
The disk layout needs to be as flexible as possible to allow growth to be done by just
adding storage for newly added components. If the design is planned carefully at
the beginning, it is not required to make changes to already existing file systems.
Option 1 is recommended for environments that implement clusters with server
consolidation if CFS is not available.
1 - SGeSAP NFS Cluster
Optimized to provide maximum simplicity. The option is only feasible for very
simple clusters. It needs to be foreseeable that the layout and configuration won't
change over time. It comes with the disadvantage of being locked into restricted
configurations with a single SAP System and idle standby nodes. HP recommends
option 1 in case of uncertainty about potential future layout changes.
2 - SGeSAP NFS Idle Standby
Cluster
Combines maximum flexibility with the convenience of a Cluster File System. It
is the most advanced option. CFS should be used with SAP if available. The HP
Serviceguard Cluster File System requires a set of multi-node packages. The number
of packages varies with the number of disk groups and mountpoints for Cluster File
Systems. This can be a limiting factor for highly consolidated SGeSAP environments.
3 - SGeSAP CFS Cluster
Each file system that gets added to a system by SAP installation routines must be classified and
a decision has to be made:
SAP Instance Storage Considerations 23