Shared Storage Configuration

The Logical Volume Manager (LVM) manages the physical disks and presents the volumes to the database system in the form of raw devices. This section gives the steps to create the volume group and volumes, and shows how to make them available for all the nodes in the cluster.

Logical Volume Manager Steps:

1. Disks need to be properly initialized before being added into volume groups by the pvcreate command. The following step should be performed for all the disks (LUNs) we want to configure for our 9i RAC volume group(s):

$ pvcreate -f /dev/rdsk/cxtydz

( where x=instance, y=target, and z=unit)

2. Create the volume group directory with the character special file called group:

$ mkdir /dev/vg_rac

$ mknod /dev/vg_rac/group c 64 0x060000

Note: The minor numbers for the group file should be unique among all the volume groups on the system.

3. Create PV-LINKs and extend the volume group:

$ vgcreate /dev/vg_rac /dev/dsk/c0t1d0 /dev/dsk/c1t0d0

$ vgextend /dev/vg_rac /dev/dsk/c1t0d1 /dev/dsk/c0t1d1

Continue with vgextend until all the needed disks are included for the volume group(s).

4. Create logical volumes for the 9i RAC database with the command:

$ lvcreate -i 10 -I 1024 -L 100 -n Name /dev/vg_rac

-i: number of disks to stripe across

-I: stripe size in kilobytes

-L: size of logical volume in MB

5. Logical Volume Configuration

It is necessary to define raw devices for each of the following categories of files. The Oracle Database Configuration Assistant (DBCA) will create a seed database expecting the following configuration:

Raw Device for           File Size    Sample name

SYSTEM tablespace         400 MB      db_name_raw_system_400

USERS tablespace          120 MB      db_name_raw_user_120

TEMP tablespace           100 MB      db_name_raw_temp_100

An undo tablespace per

  instance                500 MB      db_name_thread_raw_undo_500

OEMREPO                    20 MB      db_name_raw_oemrepo_20

INDX tablespace            70 MB      db_name_raw_indx_70 

TOOLS tablespace           12 MB      db_name_raw_tools_12

DRYSYS tablespace          90 MB      db_name_raw_dr_90

First control file        110 MB      db_name_raw_control01_110

Second control file       110 MB      db_name_raw_control02_110

Two ONLINE redo

  log files per instance  120 MB/file db_name_thread_lognumb_120

Spfile.ora                  5 MB      db_name_raw_spfile_5

Srvmconfig                100 MB      db_name_raw_srvmconf_100

EXAMPLE                   160 MB      db_name_raw_examples_160

Note: Automatic Undo Management requires an undo tablespace per instance, therefore a minimum of 2 tablespaces are required as described above.

By following the naming convention described in the table, raw partitions are identified with the database and the raw volume type (the data contained in the raw volume). Raw volume size is also identified using this method.

In the sample names listed in the table, the string db_name should be replaced with the actual database name, thread is the thread number of the instance, and log number is the log number within a thread.

It is recommended that symbolic links be created for each of these raw files on all systems of the RAC cluster.

6. Check to see if the volume groups are properly created and available:

$ strings /etc/lvmtab

$ vgdisplay -v /dev/vg_rac

7. Change the permission of the database volume group vg_ops to 777, change the permissions of all raw logical volumes to 660, and the owner to oracle:dba.

$ chmod 777 /dev/vg_rac

$ chmod 660 /dev/vg_rac/r*

$ chown oracle:dba /dev/vg_rac/r*

8. Export the volume group:

First de-activate the volume group

$ vgchange -a n /dev/vg_rac

Create the volume group map file:

$ vgexport -v -p -s -m mapfile /dev/vg_rac

Copy the map file to all the nodes in the cluster:

$ rcp mapfile system_name:target_directory

$ rcp map_ops nodeB:/tmp/scripts

$ chown oracle:dba /dev/vg_rac/r*

9. Import the volume group on the second node in the cluster.

Create a volume group directory with the character special file called group:

$ mkdir /dev/vg_rac

$ mknod /dev/vg_rac/group c 64 0x060000

Note: The minor number has to be the same as on the other node.

Import the volume group:

$ vgimport -v -s -m mapfile /dev/vg_rac

Check to see if devices are imported:

$ strings /etc/lvmtab

Next, we will examine how ServiceGuard is configured to support the RAC implementation.