High Availability for Oracle ASM using HP Serviceguard Solutions, September 2010

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High Availability for Oracle ASM using

HP Serviceguard Solutions

Technical white paper

Table of contents

High Availability for Oracle ASM using HP Serviceguard Solutions ........................................................... 1

Introduction ......................................................................................................................................... 2

Terms and definitions ........................................................................................................................... 2

ASM background ................................................................................................................................ 3

What is Automatic Storage Management? .......................................................................................... 3

Figure 1 contrasts the Oracle storage hierarchy as it appears when platform or third-party volume managers and

file systems are used for Oracle data ..................................................................................................... 3

HP Serviceguard support for ASM on HP-UX 11i v2 ................................................................................. 4

Overview ........................................................................................................................................ 4

Why ASM over LVM? ....................................................................................................................... 4

Configuring LVM volume groups for ASM disk groups .......................................................................... 4

Sample command sequence for configuring LVM volume groups ........................................................... 5

HP Serviceguard support for ASM on HP-UX 11i v3 and later ................................................................... 7

Framework for ASM support with Serviceguard ....................................................................................... 7

How the Oracle Database Toolkit starts/stops/monitors the ASM instance .............................................. 8

How the Oracle Database Toolkit starts/stops/monitors the database instance ........................................ 8

HP Serviceguard Toolkit internal file structure ..................................................................................... 10

ASM file descriptor release ............................................................................................................. 11

Installing, configuring, and troubleshooting ........................................................................................... 12

Related documentation ....................................................................................................................... 13

Appendix ......................................................................................................................................... 13

Sample Command Sequence for Configuring LVM Volume Groups on HP-UX 11i v3 or later .................. 13

Call to action .................................................................................................................................... 14

Summary of content (14 pages)

PAGE 1
High Availability for Oracle ASM using HP Serviceguard Solutions Technical white paper Table of contents High Availability for Oracle ASM using HP Serviceguard Solutions ........................................................... 1 Introduction ......................................................................................................................................... 2 Terms and definitions ........................................................................................................
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Introduction This document discusses the use of the Oracle database server feature called Automatic Storage Management (ASM) in configurations of HP Serviceguard for single database instance failover. HP Serviceguard Extension for RAC (SGeRAC) supports ASM with Oracle RAC on both ASM over raw devices and ASM over SLVM. For Oracle single instance failover, HP Serviceguard support is for ASM over LVM where the members of the ASM disk groups are raw logical volumes managed by LVM.
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ASM background What is Automatic Storage Management? Automatic Storage Management is a feature provided in Oracle 10g or later to simplify the database files management. ASM provides file system and volume management capabilities directly inside the Oracle database kernel, allowing volumes and disk management with familiar SQL statements in Oracle.
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HP Serviceguard support for ASM on HP-UX 11i v2 Overview This document describes how to configure Oracle ASM database with HP Serviceguard for high availability using the Oracle database Toolkit available in the Serviceguard Enterprise Cluster Master Toolkit bundle (ECMT). For information about the supported versions of Serviceguard ECMT with Oracle database and Serviceguard, look at the Serviceguard ECMT support matrix available at http://www.hp.
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Further, the default retry behavior of LVM could result in an I/O operation on an LVM LV taking an indefinitely long period of time. This behavior could impede ASM retry and rebalance capabilities; hence a finite timeout must be configured for each LVM LV. For example, the timeout could be configured to the value (total number of physical paths to the PV * PV timeout), providing enough time for LVM to try all available paths, if needed.
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• For each of the two PVs, create a corresponding LV – Create an LV of zero length – Mark the LV as contiguous – Extend each LV to the maximum size possible on that PV (the number of extents available in a PV can be determined via vgdisplay -v ) – Configure LV timeouts, based on the PV timeout and number of physical paths, as described in the previous section. If a PV timeout has been explicitly set, its value can be displayed via pvdisplay -v.
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HP Serviceguard support for ASM on HP-UX 11i v3 and later This document describes how to configure Oracle ASM database with HP Serviceguard for high availability using the Oracle database Toolkit in Serviceguard ECMT. Look at the Serviceguard ECMT support matrix available at http://www.hp.com/go/hpux-serviceguard-docs HP Enterprise Cluster Master Toolkit for the supported versions of Serviceguard ECMT, Serviceguard and Oracle.
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How the Oracle Database Toolkit starts/stops/monitors the ASM instance The Oracle database Toolkit MNP for the ASM instance provides start and stop functions for the ASM instance and has a service for checking the status of the ASM instance. The start function switches to the ASM software owner user id by executing the ‘su’ command. It starts the ASM instance specified by the user using the sqlplus commands.
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Figure 3: HP Serviceguard ASM environment Oracle DBs in ASM Diskgroup Node 1 Read/write Disk group headers Rebalance Disk group data Read/Write DB Files Node 2 Read/Write DB Files DB0 DB1 Disk groups mounted on startup Disk groups mounted on startup Get DB File Extent Maps Get DB File Extent Maps ASM instance ASM instance Disk groups not mounted on startup Disk groups not mounted on startup Read/write Disk group headers Rebalance Disk group data The diagram below shows the scenario when DB1
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HP Serviceguard Toolkit internal file structure HP provides a set of scripts for the framework proposed for ASM integration with Serviceguard. The Serviceguard ECMT Oracle scripts contain the instance specific logic to start/stop/monitor both the ASM and the database instance. These scripts support both legacy and the modular method of packaging. Even though Legacy method of packaging is supported, it is deprecated now and will not be supported in future.
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Figure 6: Internal file structure for modular packages Instance specific configuration and logic Serviceguard specific configuration and logic Toolkit Configuration file (haoracle.conf) ASM/DB instance Configuration File Toolkit Interface Script (toolkit.sh) calls sources calls Serviceguard Package Manager calls sources ECMT Oracle Toolkit Module Script calls Serviceguard Master Control Script Toolkit start/stop/ monitor scripts (haoracle.sh, haoracle.mon, haoracle_sql.sh, halistener.
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The toolkit package parameter KILL_ASM_FOREGROUNDS determines whether the scripts should kill the ASM foregrounds if the file descriptors are open on the dismounted disk group volumes. The ASM PMON process will recover any foreground processes that were killed. This parameter can be set either to yes or no only. Default value is “yes”.
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Related documentation • HP Serviceguard Solutions: www.hp.com/go/serviceguardsolutions • HP Serviceguard Solutions Technical Documentation: http://www.hp.com/go/hpux-serviceguard-docs • Latest edition of Managing Serviceguard user guide, at http://www.hp.com/go/hpux-serviceguard-docs HP Serviceguard • Oracle Database Installation Guide at http://www.oracle.com/technology/documentation/index.
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• Null out the initial part of each LV user data area to ensure ASM accepts the LV as an ASM disk group member. Note that we are zeroing out the LV data area, not its metadata. It is the ASM metadata that is being cleared.