How To Create Oracle Asm Disk Linux

Building Virtual File System for ASM Disks

Automatic Storage Management (ASM) employs provisioned disks for creating disk groups. The following steps instantiate the virtual disks used to create a virtual file system, without creating disks partitioning.

§ Create zero-filled flat files

Run the 'dd' command to create the zero-filled flat files. Optionally, in between each 'dd' command, the Operating System 'sync' command is executed to write buffered data to the disk, releasing memory for the next 'dd' command. The size of the file is specified using the 'count' attribute. The following example creates a zero-filled file of size 20GB.

#dd if=/dev/zero of=/u01/asmdsks/_asm_file_vdisk_01 bs=1k count=20971520

§ Attach a loopback device for each file

Use the Operating System utility 'losetup' to attach the first Linux loopback device with the flat file created. Ensure the loopback devices /dev/loop1 to /dev/loop7 are available. Test each loopback device availability; to test the first loopback device, type the following the command:

# /sbin/losetup /dev/loop1

§ Link the virtual loopback device

Use the command 'ln' to alias the loopback devices to be presented as virtual block devices.

§ Create the ASM Disk

The last step is to use Oracle ASM command 'oracleasm createdisk' to provision the files as virtual ASM disk.

Warning! This virtual disk setup is for training purposes. It should not be employed for a production environment. The script is designed to create up to 7 ASM disks only.

#-----------------------------------------------------------------

#-- DISCLAIMER:

#--

#-- This script is provided for educational purposes only.

#-- The script has been tested on an Oracle Database 11g instance

#-- and run as intended. However; prior to using the script on

#-- production systems, a dynamic test should be conducted prior

#-- to deployment.

#--

#------------------------------------------------------------------

#!/bin/bash

echo `date`

echo "Enter non-existing ASM directory or press ENTER to exit, "

echo "Example: /u01/ASMDSKS: "; read vdir

if [ -d $vdir ]; then

echo "Directory exit"; exit -1

elif [[ $vdir != /* ]]; then

echo "Invalid directory, example /u01/ASMDSKS"; exit -1

else

echo "Enter number of virtual disks followed by size, "

echo "Example: 4 4194304: "; read vdsk vsize

if [[ "$vdsk" = *[!2-7]* ]]; then

echo "Invalid argument value, Example: 2 4096"; exit -1

else

mkdir -p $vdir

for i in $(eval echo "{1..$vdsk}")

sync; echo 3 > /proc/sys/vm/drop_caches

echo "Creating $vdir/_asm_file_vdisk_0$i"

dd if=/dev/zero of=$vdir/_asm_file_vdisk_0$i\

bs=1024 obs=1024 count=$vsize status=noxfer

echo "De-attaching /dev/loop$i"

/sbin/losetup -d /dev/loop$i

/sbin/losetup /dev/loop$i $vdir/_asm_file_vdisk_0$i

case "$i" in

2) echo "Creating ASM_DISK0$i";

ln -s /dev/loop$i /dev/xvdd;

/usr/sbin/oracleasm createdisk ASM_DISK0$i /dev/xvdd;;

3) echo "Creating ASM_DISK0$i";

ln -s /dev/loop$i /dev/xvde;

/usr/sbin/oracleasm createdisk ASM_DISK0$i /dev/xvde;;

4) echo "Creating ASM_DISK0$i";

ln -s /dev/loop$i /dev/xvdf;

/usr/sbin/oracleasm createdisk ASM_DISK0$i /dev/xvdf;;

5) echo "Creating ASM_DISK0$i";

ln -s /dev/loop$i /dev/xvdg;

/usr/sbin/oracleasm createdisk ASM_DISK0$i /dev/xvdg;;

6) echo "Creating ASM_DISK0$i";

ln -s /dev/loop$i /dev/xvdh;

/usr/sbin/oracleasm createdisk ASM_DISK0$i /dev/xvdh;;

7) echo "Creating ASM_DISK0$i";

ln -s /dev/loop$i /dev/xvdi;

/usr/sbin/oracleasm createdisk ASM_DISK0$i /dev/xvdi;;

esac

done

echo "Scanning ASM disk..."

echo ""

/usr/sbin/oracleasm listdisks

Oracle GoldenGate 12c

The above is an excerpt from the upcoming 12c book Oracle GoldenGate 12c: A Hands-on Guide to Data Replication & Integration using Oracle & SQL Server.

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