Installing ASM Grid Infrastructure on Linux

Ø  First we will discuss about ASM and its Features..

1. What is ASM ?

ASM is a file system provided by oracle for storing data with high performance I/O and failure proof.

2. Advantages of Using ASM?

 * Two major reasons for using ASM ie Performance & Protection.

 * ASM gives performance and redundancy through Striping & Mirroring

STRIPPING:-

 

   ASM stripes all files across every disk which are part of a diskgroup.

 

   ASM have 2 types of striping Coarse & Fine Striping

   Coarse Striping :

   Uses a stripe size of 1MB. you can use coarse striping for every file in your database except   ctlfile,online redologfiles and falshback files.

   Fine Striping :

   Uses a stripe size 128Kb, you can use fine striping for ctlfiles, online redologfiles and flashback       files.

MIRRORING:-

Mirroring means data redundancy, This means if you lose disk,you can use the mirror disk to continue operations.

When a disk in a groups fails ASM rebuilds the failed disk using mirrored extents from other disks in the group.

When ASM reconstructs a failed disk, the storage system takes a small performance hit,

because ASM requires some extra I/O to reconstruct the failed device.

TYPES OF MIRRORING:-

ASM supports 3 types of disk mirroring, each with a different level of data redundancy.

External Redundancy, Normal Redundancy and High Redundancy.

External = doesn’t have failure groups and no mirroring strategy.

Normal = It have 2 way mirroring of fields in a diskgroup.

High = It have 3 failure groups.

FAILURE GROUPS:-

If any disk fails ASM can survive the disaster and reconstruct the lost disks from the mirror copies.

Background Process in ASM :-

•  Oracle ASM instances uses several Oracle Background Process, Such as SMON,PMON and             LGWR.  
•    For managing ASM oracle uses 2 instances.       

   RBAL = The coordinates disk activity.

  

   ARBn = Performs the re-balancing like moving data extents.

   ASMB = Connects to asm instance and links the ASM instance.

  Installation of ASM-GRID INFRASTRUCTURE on Linux

 Ø  Make Partitions using Fdisk

] fdisk /dev/sdb

  n = new partation

  p = primary partation

  1 = 

  +20g = Partation Size

   W = Save & Exit

 Ø  Run Partprobe to update the OS about Partitions.

] partprobe /dev/sdb

 Ø   Check Partitions, check the Ownership and Permissions from Unix Team

] fdisk -l  

] Chown -R oracle:dba /dev/sdb1 or sdb2 or sdb*

] Chmod -R 775 /dev/sdb* 

] xhost +

] Su - oracle

grid] ./runInstaller

Ø   Set the Environment Variable

] cat > grid.env

export ORACLE_HOME=/u01/home/grid/oracle/product/11.2.0/grid

export PATH=$ORACLE_HOME/bin:$PATH:.

] .grid.env

] export ORACLE_SID=+ASM

] conn / as sysasm

Ø   Check ASM status.

> Select Instance_name,status from v$instance;

] asmcmd

asmcmd> ls

asmcmd ] lsdisk

asmcmd ] ls -ltr

Happy Learning .....