Managing Serviceguard Extension for SAP on Linux (IA64 Integrity and x86_64), February 2008

Planning a File System Layout for SAP in a Serviceguard/LX Cluster Environment

About Impacted File Systems

Chapter 248

Figure 2-2 shows a two node cluster with LOCAL and SHARED mounted

/ connected storage.node

Figure 2-2 Two node cluster with LOCAL and SHARED mounted / connected

storage

LOCAL Storage

The LOCAL connected storage device “s1” can only be mounted by

cluster node “m1”, the storage device “s2” can only be mounted by cluster

node “m2”. So “s1” and “s2” storage access is LOCAL for these cluster

nodes. Sharing of data with the other cluster nodes is not required and

the other cluster nodes do not have any direct access to this storage

device.

SHARED Storage

The SHARED connected storage “s2, s3” can be mounted from any of the

cluster nodes. Storage will be shared between the cluster nodes. At some

point and time one or more of the cluster nodes will require access to the

shared storage. Depending on the type of “sharing” this can further be

classified as SHARED NFS or SHARED EXCLUSIVE.

In the SHARED EXCLUSIVE case the storage device is accessible from

any of the cluster nodes but as some point and time only one cluster node

will mount the storage exclusively in the cluster. It will be that cluster

node that requires that file system to run the SAP instance.

In the SHARED NFS case the file systems are mounted via NFS and

available to all cluster nodes (via NFS export / import) at all times.

Storage 1 Storage 2 Storage 3

Storage 4

LOCAL

storage m1

LOCAL SHARED

storage m1 + m2

LOCAL

storage m2

Node