Architecture considerations and best practices for architecting an Oracle RAC solution with Serviceguard and SGeRAC

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Figure 3 shows the combined stack.
Figure 3: Serviceguard and Oracle RAC integrated stack
In the combined stack, one needs to make sure that only SGeRAC or Oracle Clusterware manages
the cluster membership at any given time, but not both. If both pieces of software manage the cluster
at the same time, there is the possibility of conflicting cluster membership that may cause the entire
cluster to fail.
The following sections discuss the interaction between cluster components in the combined stack,
network high-availability (HA)_configuration choices, and storage management choices.
Cluster management—who controls what and when?
In an Oracle RAC with SGeRAC configuration, there are three cluster components: SGeRAC, Oracle
Clusterware, and RAC. Each of these components has its own critical resources that keep the RAC
cluster running. When one or more of these resources fail, the appropriate cluster component will
perform a recovery to maintain cluster integrity. A time delay is used to ensure only one cluster
component controls the recovery at any given time. This mechanism works well but may also introduce
a long recovery time if the configuration is not properly designed.
The remainder of this section discusses the default time delay configuration for each component and
how recovery is handled by these components when a fault occurs.
When Oracle Clusterware is installed in an SGeRAC environment, the CSS MISSCOUNT value is set
to 600 seconds. This adjustment is to make sure Serviceguard has enough time to resolve the cluster
membership before CSS decides its own cluster membership. Once the cluster reforms, SGeRAC will
present the new cluster membership to Oracle Clusterware via the Oracle-supplied cluster
membership API.
HP supports and strongly recommends
Oracle RAC configurations that use:
Oracle RAC with HP Serviceguard Cluster
Membership and Storage Management
•
SGeRAC cluster membership providing
RAC membership
•
HP -
UX supported volume managers and
file
systems to store Oracle and
application data
–
e.g ., SLVM, CVM, and CFS
•
The Serviceguard package manager to
Provide high availability for applications
running on the same cluster as the RAC
software
SG
Integration
code
-
SG-Managed
Applications
Oracle
Clusterware
Membership (CSS)
SG
Package
Manager
RAC
SGeRAC
: SG cluster membership
File
systems
Raw volumes
ASM
SG/CFS
Raw Disks
HP
-
UX
11i v3
HP Volume Managers
HP-UX
CRS
SG clustering components
Oracle components
CRS
Resource
definition