Setup ASM with Loopback device on FC6

First, this document is very helpfull for me:

• http://www.osdev.org/wiki/Loopback_Device.
• http://www.dizwell.com/prod/node/34.

Here are some steps that I was doing to try ASM on my notebook with Oracle10g R 2 on FC 6:

• I create a disk image for 500M with this command (as root):

dd if=/dev/zero of=/disk2.img bs=516096c count=1000
dd if=/dev/zero of=/disk3.img bs=516096c count=1000

• then i mount those disk image as local device, so that file will be threaded as phisycal disk

losetup /dev/loop0 /disk2.img
losetup /dev/loop1 /disk3.img

Note: if you want to detach loopback device from disk image, you can use this command:
losetup -d /dev/loop?

• We should configure and run CSS (Cluster Synchronization Service) before configure ASM

$ORACLE_HOME/bin/localconfig add

that command will create init.cssd service in /etc/init.d and /etc/oracle directory store some information and location to store any information from cssd service.
You can call CSS service with this command:

/etc/init.d/init.cssd start

• download the latest ASMlib source from OracleASM project. (please read some discussion at this). In that directory, there is no configure script, so I download ASMLib kernel module (oracleasm-2.0.3.tar.gz) and use configure script from that. The compilation is success. After make install, we will get /etc/init.d/oracleasm service script.
• now, I have to make oracleasm kernel module is launched safely.

/etc/init.d/oracleasm configure
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) [y]: n
Fix permissions of Oracle ASM disks on boot (y/n) [y]:
Writing Oracle ASM library driver configuration: [ OK ]
Unmounting ASMlib driver filesystem: [ OK ]

• in my case, kernel module oracleasm can't be found by modprobe -r oracleasm, so, I try to call with

insmod /lib/module/{kernel_version}/extra/oracleasm.ko

I changed modprobe -s "$MODNAME" command with insmod command like above.

• To make our local loopback disk become ASM disk, I have to make ASM disk with /etc/init.d/oracleasm createdisk command :

/etc/init.d/oracleasm createdisk ASMD0 /dev/loop0
/etc/init.d/oracleasm createdisk ASMD1 /dev/loop1

With those command, there are trow ASMD* disk that will create in my /dev/oracleasm/disks. I can check with this command:
/etc/init.d/oracleasm listdisks
ASMD0
ASMD1

• Based on dizwell.com blog, I should prepare ASM instance with these commands:

as oracle user, I create /tmp/init+ASM.ora that have some parameters declaration like these:
INSTANCE_TYPE=ASM
DB_UNIQUE_NAME=+ASM
LARGE_POOL_SIZE=8M

$ export ORACLE_SID=+ASM
$ sqlplus / as sysdba
SQL> create spfile from pfile='/tmp/init+ASM.ora';
SQL> startup nomount;
SQL> alter system set ASM_DISKSTRING=''/dev/oracleasm/disks/*';
SQL> shutdown;

• now, I will configure ASM with dbca. I choose Configure Automatic Storage Management, and give the group disk with DGROUP1 and choose all of ASMD* as the members.

• Now, with dbca I can create a new database which is using ASM as the database storage.

This is my first experience using ASM with loopback device as 'phisical' storage for Oracle. I still need to learn more about Oracle RAC. I have blogroll that may be can help you too to learn about OracleRAC. If you have any other great tutorial about this, please share with me. Thanks.