Best Practices for SGeRAC and Oracle RAC on HP-UX 11i, March 2009

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For Oracle Clusterware data files, starting with 10.2.0.2, Oracle introduced a CSS disktimeout to
capture hang I/O hangs; however, for configurations with SGeRAC, the disktimeout is automatically
set to three seconds lower than CSS MISSCOUNT and is only indirectly configurable based on CSS
MISSCOUNT. Setting I/O timeouts for SLVM or CVM does not affect disktimeout. If CSS receives
I/O error, CSS attempts to reopen Oracle Clusterware data files until disktimeout is reached. The
default MISSCOUNT is 600 seconds for configurations with SGeRAC.
Table 1 shows a quick comparison between the various storage options and the details of each
option are discussed.
Table 1. Storage comparison
Advantages Disadvantages I/O Timeout
CFS
Cluster file system, online
changes
Requires Serviceguard Storage
Management Suite
30 seconds per link
CVM Online changes Archive package failover 30 seconds per link
SLVM
Established non-intrusive
solution, online node and
volume group changes
Online SLVM volume
reconfigurations available on
one node, archive package
failover
Default is no timeout
ASM over Raw Devices
Zero impact on database
recovery operations
Requires file system for Oracle
binaries, alert log, OC data
files, application binaries and
data
Default timeout based on
version of HP-UX 11i
ASM over SLVM
Zero impact on database
recovery operations
Online SLVM volume
reconfigurations available on
one node
For OC data files, default is no
timeout. For RAC data files,
default is set to 30 seconds per
link
CFS
Serviceguard supports CFS using two additional new features: simple package dependency and multi-
node packages. CFS provides the following notable features:
• Single home for Oracle Clusterware
• Single ORACLE database home
• Single archive designation
The following is a sample mapping based on the preferred storage configuration:
• Disk Group (DG)/CFS for Oracle Clusterware home when single home for ease of management is
important; or use local file systems for Oracle Clusterware home when minimal interference
between nodes is desired.
• DG/CFS for Oracle database home when single home for ease of management is important; or use
local file systems for Oracle database home when minimal interference between nodes is desired.
• DG/CFS for OCR and Voting Disk
• DG/CFS for Oracle RAC database data files
o Recommendation: one DG per database
• DG/CFS for flash recovery and/or archive destination
o Recommendation: one DG per database