Thursday, May 14, 2009

Automatic Storage Management

ASM using ASMLib and Raw Devices:
This is a beutiful document which covers almost the full setup for an ASM (Automatic Storage Management ) environment. For your reference it covers the following:

  • Introduction
  • Partition the Disks
  • ASMLib Installation
  • Raw Device Setup
  • ASM Creation
  • Database Creation
  • Switching from Raw Devices to ASMLib
  • Switching from ASMLib to Raw Devices
  • Performance Comparison

Automatic Storage Management (ASM) in Oracle Database 10g:
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This document covers a small part of Oracle Automatic Storage Management (ASM) Commands to Manage an ASM instance and database. Also You will get a quick idea how to Migrate a Oracle single instance database to ASM using RMAN.

Commanding ASM (Automatic Storage Management)
Access, transfer, and administer ASM files without SQL commands.

Oracle Database 10g Release 1 introduced Automatic Storage Management (ASM), a new framework for managing Oracle database files. ASM provided a foundation for highly efficient storage management with kernelized asynchronous I/O, direct I/O, redundancy, striping, and an easy way to manage storage. ASM includes volume management functionality similar to that of a generic logical volume manager (LVM).

Managing ASM through SQL interfaces in Oracle Database 10g Release 1 posed a challenge for system administrators who were not very familiar with SQL and preferred a more conventional command-line interface. In Oracle Database 10g Release 2, you have an option to manage the ASM files by using ASMCMD—a powerful and easy-to-use command-line tool.

In Oracle Database 10g Release 1, ASM disk groups are not visible outside the database for regular file system administration tasks such as copying and creating directories. In Oracle Database 10g Release 2, however, you can transfer the files from ASM to locations outside of the disk groups via FTP and through a Web browser using HTTP.

This article shows you how to use these enhancements in ASM to accomplish everyday tasks.

Set asmcmd prompt display:
You can invoke asmcmd with the -p option to display the current path, very similar to the UNIX/Linux.
export PS1


asmcmd command line history:
The asmcmd utility does not provide a command history with the up-arrow key. With rlwrapinstalled, this can be fixed by adding the following entry to the ~oracle/.bashrc file:

alias asmcmd='rlwrap asmcmd'

Automatic Storage Manager (ASM) Enhancements in Oracle Database 11g Release 1:

SQL Help for ASM (Automatic Storage Management):
Create Diskgroup:
Use the CREATE DISKGROUP clause to create a collection of disks. Oracle Database manages a disk group as a logical unit and evenly spreads each file across the disks to balance I/O. Oracle Database also automatically distributes database files across all available disks in disk groups and rebalances storage automatically whenever the storage configuration changes.

This statement creates a disk group, assigns one or more disks to the disk group, and mounts the disk group for the first time. If you want Automatic Storage Management to mount the disk group automatically in subsequent instances, you must add the disk group name to the value of the ASM_DISKGROUPS initialization parameter in the initialization parameter file. If you use an SPFILE, then the disk group is added to the initialization parameter automatically.

Alter Diskgroup:
The ALTER DISKGROUP statement lets you perform a number of operations on a disk group or on the disks in a disk group.

Drop Diskgroup:
The DROP DISKGROUP statement lets you drop an Automatic Storage Management disk group along with all the files in the disk group. Automatic Storage Management first ensures that no files in the disk group are open. It then drops the disk group and all its member disks and clears the disk header.

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