Oracleasm Utility For ASMLIB

In this article, we are going to have look on Oracleasm Utility For ASMLIB.These lines explain the technical definition of Oracleasm The oracleasm command utility is part of the Oracle ASMLib, and you only use oracleasm commands when you want Oracle ASMLib to be able to access your ASM disks.

Oracle notes that the ASMLib is an optional support library for the Automatic Storage Management feature of ASM.  They claim that ASMLib simplifies database administration and greatly reduces kernel resource usage, and eliminates the need for the DBA to directly manage potentially thousands of Oracle database files, requiring only the management of ASM disk groups.

ASMlib driver is required on Linux operating systems, to enable a disk readable by ASM. Without ASMLIB, disks can’t be used at asm disks.

Below are the steps for configuring ASMlib and marking disks as ASM.

Download Asmlib:
You can download these rpm packages directly from OTN:

http://www.oracle.com/technetwork/server-storage/linux/downloads/index-088143.html

Else, if your system is registered with ULN, then you can download directly using yum as below.

– Run as root on the database server

yum install oracleasm-support oracleasmlib oracleasm

  2. Configure oracleasm:[ Do on all nodes if RAC]

[root@b20e4bay04 mapper]# /etc/init.d/oracleasm configure
Configuring the Oracle ASM library driver.

This will configure the on-boot properties of the Oracle ASM library
driver. The following questions will determine whether the driver is
loaded on boot and what permissions it will have. The current values
will be shown in brackets ('[]'). Hitting without typing an
answer will keep that current value. Ctrl-C will abort.

Default user to own the driver interface []: oracle
Default group to own the driver interface []: oinstall
Start Oracle ASM library driver on boot (y/n) [n]: y
Scan for Oracle ASM disks on boot (y/n) [y]: y
Writing Oracle ASM library driver configuration: done
Initializing the Oracle ASMLib driver: [ OK ]
Scanning the system for Oracle ASMLib disks: [ OK ]

   3. Start oracleasm:

# /etc/init.d/oracleasm start
Initializing the Oracle ASMLib driver: [ OK ]
Scanning the system for Oracle ASMLib disks: [ OK ]

Now as we have configured and started the oracleasm, we can proceed with making the disks as ASM disk.

4.Create ASM disk [ Do only from one node ]

Create disk need to be run only from one node

# /etc/init.d/oracleasm createdisk MGMTP1 /dev/mapper/mpathup1
Marking disk "MGMTP1" as an ASM disk: [ OK ]

 5.Now list and scan the disks [ On both the nodes ]

Once disk is created, you need to scan the disks using scandisks on all the nodes,

# /etc/init.d/oracleasm scandisks
# /etc/init.d/oracleasm listdisks

Now, these ASM disks are ready to be added to ASM disk group.

Automatic start can be enabled or disabled with the ‘enable’ and ‘disable’ options to /etc/init.d/oracleasm:

— Disable

# /etc/init.d/oracleasm disable
Writing Oracle ASM library driver configuration [ OK ]
Unmounting ASMlib driver filesystem [ OK ]
Unloading module "oracleasm" [ OK ]

— Enable

# /etc/init.d/oracleasm enable
Writing Oracle ASM library driver configuration [ OK ]
Loading module "oracleasm" [ OK ]
Mounting ASMlib driver filesystem [ OK ]
Scanning system for ASM disks [ OK ]

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