Veritas Storage Foundation 5.0 for Oracle RAC Configuration Guide Extracts for HP Serviceguard Storage Management Suite, Second Edition, May 2008

Introducing Serviceguard Extension for RAC
Communication Infrastructure
Chapter 1
15
Communication Requirements
End-users on a client system are unaware that they are accessing a database hosted by
multiple instances. The key to performing I/O to a database accessed by multiple
instances is communication between the processes. Each layer or component in the data
stack must reliably communicate with its peer on other nodes to function properly. RAC
instances must communicate to coordinate protection of data blocks in the database.
ODM processes must communicate to coordinate data file protection and access across
the cluster. CFS coordinates metadata updates for file systems, while CVM coordinates
the status of logical volumes and maps.
Figure 1-3 Communication Stack
RAC
ODM
CFS
CVM
SG/SGeRAC Core
GAB LLT
SGORAC Cluster State
Cache Fusion/Lock Mgmt
Data File Management
File System MetaData
Volume Management
RAC
ODM
CFS
CVM
SG/SGeRAC Core
GAB
LLT