Thursday, May 13, 2010

ASM in Windows server

Preparing Disks for ASM: Windows NT

To simulate implementation of ASM in the Windows NT environment, I first created raw disk partitions on some of my hard drives. Fortunately, I had extra space on three of the four disks in my test server, so I created several primary disk partitions sized at 100MB on each of those three drives using the Windows Disk Partitioning utility (DISKPART.EXE):

C:\> select disk 2
C:\> Disk 2 selected.
C:\> create partition primary size=100
C:\> Partition created.
C:\> create partition primary size=100
C:\> Partition created.
C:\> create partition primary size=100
C:\> Partition created.
C:\> select disk 3
C:\> Disk 3 selected.
C:\> create partition primary size=100
C:\> Partition created.

Once the partitions are completed, I used the ASMTOOLG.EXE utility to "stamp" each partition with an ASM label so that Oracle
can recognize these partitions as candidate disks for the ASM instance. I executed the ASMTOOLG.EXE program from the /bin
directory of the Oracle home path for my Windows NT database. Figure 2.1.2 shows the initial screen that this GUI tool
presented, and Figure 2.1.3 shows the screen that confirmed the creation of the ASM labels. Once the labels were assigned,
I then re-invoked ASMTOOLG to confirm them (see Figure 2.1.4). I will also use ASMTOOLG to remove the labels prior to
removing these partitions once my simulation is completed

Creating an ASM Instance Using DBCA in Linux
I used this same methodology to create an ASM instance in Linux using DBCA. The only significant difference was the contents of the Disk Selection window (Figure 2.2.9), which instead showed the candidate disks I had previously created on that server for the Linux environment. In either of these cases, the end result is the same: Once I clicked on the Cancel button on the last screen, Oracle dismounted the ASM disk group I had created and then shut down the ASM instance as well.

Creating an ASM Instance without Using DBCA
Of course, I don't have to use DBCA to create an ASM instance. Personally, I prefer to use command scripts to create my database because it is easier to customize the scripts to create other ASM instances in the future, and it also gives me complete control over what Oracle is doing "behind the screen." In addition, an ASM instance is extremely easy to create because no CREATE DATABASE script is required, just an initialization parameter file like the one shown in Listing 2.2. Besides the usual initialization parameters for trace file directories, there are only a few additional ones required to create an ASM instance:

ASM Initialization Parameters

Initialization Parameter

Defines the instance as an ASM instance. This is the only required parameter to identify an ASM instance; the remainder can be left at their defaults

Defines the service provider name for which this ASM instance manages disk groups. +ASM is the default value, and should not be modified unless multiple ASM instances are on the same node

Controls rebalance operation speed. Values range from 1 to 11, with 11 being the fastest. If omitted, this value defaults to 1. The number of slaves is derived from the parallelization level specified in a manual rebalance command (POWER), or by the ASM_POWER_LIMIT parameter

An operating system dependent value; used by ASM to limit the set of disks considered for discovery

Describes the list of ASM disk group names to be mounted by an ASM instance at startup, or whenever the ALTER DISKGROUP ALL MOUNT command is used

The LARGE POOL size. This must be set to a minimum of 8MB, but Oracle recommends setting this to 16MB

To create the ASM instance without using DBCA, I first made sure that I had created the directories I specified for BACKGROUND_DUMP_DEST, CORE_DUMP_DEST, and USER_DUMP_DEST. I also created a password file for the instance using the ORAPWD utility. (This is important, because when you attempt to connect to the ASM instance from Enterprise Manager, it will expect the instance to have the REMOTE_LOGIN_PASSWORDFILE initialization parameter set to EXCLUSIVE so that the instance can be contacted remotely and that means a password file will be required.)

ORAPWD file=c:\oracle\app\product\10.1.0\db_1\database\PWD+ASM.ora password=oracle
After I had made sure that the Oracle Cluster Services service was started in my Windows NT environment - it is usually named OracleCSService in the list of Windows Services that I can start - I then simply pointed my MS-DOS command window at the database instance by setting the value for ORACLE_SID to +ASM, started a SQL*Plus session, created an SPFILE from the parameter file, and then started the ASM instance in NOMOUNT mode:

C:\> sqlplus "sys as sysdba"
SQL> Connected to an idle instance.
SQL> create spfile from pfile=c:\init+asm.ora;
SQL> File created.
SQL> startup nomount;
SQL> ASM instance started

# Standard ASM instance initialization parameters
*.asm_power_limit = 5
*.db_unique_name = '+ASM'
*.instance_type = 'asm'
*.large_pool_size = 16M

# Background, core, and user trace file directories. These will need
# to exist before starting the instance and configured for the server's
# operating system as appropriate
*.background_dump_dest = '/u01/app/oracle/admin/+ASM/bdump'
*.core_dump_dest = '/u01/app/oracle/admin/+ASM/cdump'
*.user_dump_dest = '/u01/app/oracle/admin/+ASM/udump'

# This requires a password file for the ASM instance, needed by
# Enterprise Manager for a connection as SYS:

# ASM candidate disk search string. It's not required, but it does help
# Oracle find the candidate disks more easily
*.asm_diskstring = '\\.\ORCLDISK*' # For Windows environment
*.asm_diskstring = '/u03/asmdisks/*', '/u04/asmdisks/*',# For Red Hat Linux environment

# ASM Mountable Disk Group(s). These can be activated after the ASM
# Instance has been created.

-- Create ASM disk group in NT environment

-- Create ASM disk group in Linux environment

ASMTOOL -create c:\asmdisks\asmdisk1 250


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