3 Configuring Oracle Clusterware and Oracle Database Storage

3.1.1 Overview of Storage Options

Use the information in this overview to help you select your storage option.

http://metalink.oracle.com

http://oss.oracle.com/projects/ocfs2/

3.1.2 Checking for Available Shared Storage with CVU

To check for all shared file systems available across all nodes on the cluster on a supported shared file system, use the following command:

/mountpoint/crs/Disk1/cluvfy/runcluvfy.sh comp ssa -n node_list

If you want to check the shared accessibility of a specific shared storage type to specific nodes in your cluster, then use the following command syntax:

/mountpoint/crs/Disk1/cluvfy/runcluvfy.sh comp ssa -n node_list -s storageID_list

In the preceding syntax examples, the variable mountpoint is the mountpoint path of the installation media, the variable node_list is the list of nodes you want to check, separated by commas, and the variable storageID_list is the list of storage device IDs for the storage devices managed by the file system type that you want to check.

For example, if you want to check the shared accessibility from node1 and node2 of storage devices /dev/sdb and /dev/sdc, and your mountpoint is /dev/dvdrom/, then enter the following command:

/dev/dvdrom/crs/Disk1/cluvfy/runcluvfy.sh comp ssa -n node1,node2 -s /dev/sdb,/dev/sdc

If you do not specify storage device IDs in the command, then the command searches for all available storage devices connected to the nodes on the list.

3.2.1 Requirements for Using a File System for Oracle Clusterware Files

To use a file system for Oracle Clusterware files, the file system must comply with the following requirements:

• To use a cluster file system, it must be a supported cluster file system, as listed in the section "Deciding to Use a Cluster File System for Data Files".

• To use an NFS file system, it must be on a certified NAS device.

  
  

  Note: If you are using a shared file system on a NAS device to store a shared Oracle home directory for Oracle Clusterware or RAC, then you must use the same NAS device for Oracle Clusterware file storage.

  
  

• If you choose to place your Oracle Cluster Registry (OCR) files on a shared file system, then one of the following must be true:

  • The disks used for the file system are on a highly available storage device, (for example, a RAID device that implements file redundancy).

  • At least two file systems are mounted, and use the features of Oracle Database 10g Release 2 (10.2) to provide redundancy for the OCR.

• If you intend to use a shared file system to store database files, then use at least two independent file systems, with the database files on one file system, and the recovery files on a different file system.

• The oracle user must have write permissions to create the files in the path that you specify.

Use Table 3-2 to determine the partition size for shared file systems.

In Table 3-2, the total required volume size is cumulative. For example, to store all files on the shared file system, you should have at least 3.4 GB of storage available over a minimum of two volumes.

3.2.2 Deciding to Use a Cluster File System for Data Files

If you have an existing Oracle installation, then use the following command to determine if OCFS or OCFS2 is installed:

# rpm -qa | grep ocfs

If you want to install the Oracle Database files on an OCFS or OCFS2 file system, and the packages are not installed, then download them from the following Web site. Follow the instructions listed with the kit to install the packages and configure the file system:

OCFS:

http://oss.oracle.com/projects/ocfs/

OCFS2:

http://oss.oracle.com/projects/ocfs2/

3.2.3 Checking NFS Buffer Size Parameters

If you are using NFS, then you must set the values for the NFS buffer size parameters rsize and wsize to at least 16384. Oracle recommends that you use the value 32768.

For example, if you decide to use rsize and wsize buffer settings with the value 32768, then update the /etc/fstab file on each node with an entry similar to the following:

nfs_server:/vol/DATA/oradata  /home/oracle/netapp     nfs\   
rw,bg,hard,nointr,rsize=32768,wsize=32768,tcp,actimeo=0,vers=3,timeo=600

3.2.4 Creating Required Directories for Oracle Clusterware Files on Shared File Systems

Use the following instructions to create directories for Oracle Clusterware files. You can also configure shared file systems for the Oracle Database and recovery files.

To create directories for the Oracle Clusterware files on separate file systems from the Oracle base directory, follow these steps:

1. If necessary, configure the shared file systems that you want to use and mount them on each node.

   
   

   Note: The mount point that you use for the file system must be identical on each node. Ensure that the file systems are configured to mount automatically when a node restarts.

   
   

2. Use the df -h command to determine the free disk space on each mounted file system.

3. From the display, identify the file systems that you want to use:

   File Type	File System Requirements
   Oracle Clusterware files	Choose a file system with at least 120 MB of free disk space
   Database files	Choose either: A single file system with at least 1.2 GB of free disk space Two or more file systems with at least 1.2 GB of free disk space in total
   Recovery files	Choose a file system with at least 2 GB of free disk space.

   
   

   If you are using the same file system for more than one type of file, then add the disk space requirements for each type to determine the total disk space requirement.

4. Note the names of the mount point directories for the file systems that you identified.

5. If the user performing installation (typically, oracle) has permissions to create directories on the disks where you plan to install Oracle Clusterware and Oracle Database, then OUI creates the Oracle Clusterware file directory, and DBCA creates the Oracle Database file directory, and the Recovery file directory.

   If the user performing installation does not have write access, then you must create these directories manually using commands similar to the following to create the recommended subdirectories in each of the mount point directories and set the appropriate owner, group, and permissions on them:

   • Oracle Clusterware file directory:

     # mkdir /mount_point/oracrs
     # chown oracle:oinstall /mount_point/oracrs
     # chmod 775 /mount_point/oracrs
     
     

   • Database file directory:

     # mkdir /mount_point/oradata
     # chown oracle:oinstall /mount_point/oradata
     # chmod 775 /mount_point/oradata
     
     

   • Recovery file directory (flash recovery area):

     # mkdir /mount_point/flash_recovery_area
     # chown oracle:oinstall /mount_point/flash_recovery_area
     # chmod 775 /mount_point/flash_recovery_area
     
     

By making the oracle user the owner of these directories, this permits them to be read by multiple Oracle homes, including those with different OSDBA groups.

When you have completed creating subdirectories in each of the mount point directories, and set the appropriate owner, group, and permissions, you have completed OCFS or NFS configuration.

3.3.1 Clusterware File Restrictions for Logical Volume Manager on Linux

The procedures contained in this section describe how to create raw partitions for Oracle Clusterware. Although Red Hat Enterprise Linux and SUSE Linux Enterprise Server provide a Logical Volume Manager (LVM), this LVM is not cluster-aware. For this reason, Oracle does not support the use of logical volumes with RAC for either Oracle Clusterware or database files.

3.3.2 Identifying Required Raw Partitions for Clusterware Files

Table 3-3 lists the number and size of the raw partitions that you must configure for Oracle Clusterware files.

3.3.3 Creating the Required Raw Partitions on IDE, SCSI, or RAID Devices

If you intend to use IDE, SCSI, or RAID devices for the raw devices, then follow these steps:

1. If necessary, install or configure the shared disk devices that you intend to use for the raw partitions and restart the system.

   
   

   Note: Because the number of partitions that you can create on a single device is limited, you might need to create the required raw partitions on more than one device.

   
   

2. To identify the device name for the disks that you want to use, enter the following command:

   # /sbin/fdisk -l
   
   

   Depending on the type of disk, the device name can vary:

   Disk Type	Device Name Format	Description
   IDE disk	/dev/hdxn	In this example, x is a letter that identifies the IDE disk and n is the partition number. For example, /dev/hda is the first disk on the first IDE bus.
   SCSI disk	/dev/sdxn	In this example, x is a letter that identifies the SCSI disk and n is the partition number. For example, /dev/sda is the first disk on the first SCSI bus.
   RAID disk	/dev/rd/cxdypz /dev/ida/cxdypz	Depending on the RAID controller, RAID devices can have different device names. In the examples shown, x is a number that identifies the controller, y is a number that identifies the disk, and z is a number that identifies the partition. For example, /dev/ida/c0d1 is the second logical drive on the first controller.

   
   

   You can create the required raw partitions either on new devices that you added or on previously partitioned devices that have unpartitioned free space. To identify devices that have unpartitioned free space, examine the start and end cylinder numbers of the existing partitions and determine whether the device contains unused cylinders.

3. To create raw partitions on a device, enter a command similar to the following:

   # /sbin/fdisk devicename
   
   

   When creating partitions:

   • Use the p command to list the partition table of the device.

   • Use the n command to create a partition.

   • After you have created the required partitions on this device, use the w command to write the modified partition table to the device.

   • Refer to the fdisk man page for more information about creating partitions.

3.3.4 Binding the Partitions to Raw Devices

After you have created the required partitions, you must bind the partitions to raw devices on every node. However, you must first determine what raw devices are already bound to other devices. The procedure that you must follow to complete this task varies, depending on the Linux distribution that you are using:

• Red Hat:

  1. To determine what raw devices are already bound to other devices, enter the following command on every node:

     # /usr/bin/raw -qa
     
     

     Raw devices have device names in the form /dev/raw/rawn, where n is a number that identifies the raw device.

     For each device that you want to use, identify a raw device name that is unused on all nodes.

  2. Open the /etc/sysconfig/rawdevices file in any text editor and add a line similar to the following for each partition that you created:

     /dev/raw/raw1 /dev/sdb1
     
     

     Specify an unused raw device for each partition.

  3. For the raw device that you created for the Oracle Cluster Registry (OCR), enter commands similar to the following to set the owner, group, and permissions on the device file:

     # chown root:oinstall /dev/raw/rawn
     # chmod 640 /dev/raw/rawn
     
     

     By making the oinstall group the owner of the OCR, this permits the OCR to be read by multiple Oracle homes, including those with different OSDBA groups.

  4. To bind the partitions to the raw devices, enter the following command:

     # /sbin/service rawdevices restart
     
     

     The system automatically binds the devices listed in the rawdevices file when it restarts.

  5. Repeat step 2 through step 4 on each node in the cluster.

• SUSE:

  1. To determine what raw devices are already bound to other devices, enter the following command on every node:

     # /usr/sbin/raw -qa
     
     

     Raw devices have device names in the form /dev/raw/rawn, where n is a number that identifies the raw device.

     For each device that you want to use, identify a raw device name that is unused on all nodes.

  2. Open the /etc/raw file in any text editor and add a line similar to the following to associate each partition with an unused raw device:

     raw1:sdb1
     
     

  3. For the raw device that you created for the Oracle Cluster Registry, enter commands similar to the following to set the owner, group, and permissions on the device file:

     # chown root:oinstall /dev/raw/rawn
     # chmod 660 /dev/raw/rawn
     
     

  4. To bind the partitions to the raw devices, enter the following command:

     # /etc/init.d/raw start
     
     

  5. To ensure that the raw devices are bound when the system restarts, enter the following command:

     # /sbin/chkconfig raw on
     
     

  6. Repeat step 2 through step 5 on the other nodes in the cluster.

3.3.5 Completing Supported Shared Storage Configuration

When you have completed creating subdirectories in each of the mount point directories, and set the appropriate owner, group, and permissions, you have completed supported shared storage configuration.

3.5.1 Identifying Storage Requirements for Automatic Storage Management

To identify the storage requirements for using Automatic Storage Management, you must determine how many devices and the amount of free disk space that you require. To complete this task, follow these steps:

1. Determine whether you want to use Automatic Storage Management for Oracle Database files, recovery files, or both.

   
   

   Note: You do not have to use the same storage mechanism for database files and recovery files. You can use the file system for one file type and Automatic Storage Management for the other. If you choose to enable automated backups and you do not have a shared file system available, then you must choose Automatic Storage Management for recovery file storage.

   
   

   If you enable automated backups during the installation, you can choose Automatic Storage Management as the storage mechanism for recovery files by specifying an Automatic Storage Management disk group for the flash recovery area. Depending on how you choose to create a database during the installation, you have the following options:

   • If you select an installation method that runs Database Configuration Assistant in interactive mode (for example, by choosing the Advanced database configuration option) then you can decide whether you want to use the same Automatic Storage Management disk group for database files and recovery files, or use different disk groups for each file type.

     The same choice is available to you if you use Database Configuration Assistant after the installation to create a database.

   • If you select an installation method that runs Database Configuration Assistant in noninteractive mode, then you must use the same Automatic Storage Management disk group for database files and recovery files.

2. Choose the Automatic Storage Management redundancy level that you want to use for the Automatic Storage Management disk group.

   The redundancy level that you choose for the Automatic Storage Management disk group determines how Automatic Storage Management mirrors files in the disk group and determines the number of disks and amount of free disk space that you require, as follows:

   • External redundancy

     An external redundancy disk group requires a minimum of one disk device. The effective disk space in an external redundancy disk group is the sum of the disk space in all of its devices.

     Because Automatic Storage Management does not mirror data in an external redundancy disk group, Oracle recommends that you use only RAID or similar devices that provide their own data protection mechanisms as disk devices in this type of disk group.

   • Normal redundancy

     In a normal redundancy disk group, Automatic Storage Management uses two-way mirroring by default, to increase performance and reliability. A normal redundancy disk group requires a minimum of two disk devices (or two failure groups). The effective disk space in a normal redundancy disk group is half the sum of the disk space in all of its devices.

     For most installations, Oracle recommends that you select normal redundancy disk groups.

   • High redundancy

     In a high redundancy disk group, Automatic Storage Management uses three-way mirroring to increase performance and provide the highest level of reliability. A high redundancy disk group requires a minimum of three disk devices (or three failure groups). The effective disk space in a high redundancy disk group is one-third the sum of the disk space in all of its devices.

     While high redundancy disk groups do provide a high level of data protection, you should consider the greater cost of additional storage devices before deciding to select high redundancy disk groups.

3. Determine the total amount of disk space that you require for the database files and recovery files.

   Use the following table to determine the minimum number of disks and the minimum disk space requirements for installing the starter database:

   Redundancy Level	Minimum Number of Disks	Database Files	Recovery Files	Both File Types
   External	1	1.15 GB	2.3 GB	3.45 GB
   Normal	2	2.3 GB	4.6 GB	6.9 GB
   High	3	3.45 GB	6.9 GB	10.35 GB

   
   

   For RAC installations, you must also add additional disk space for the Automatic Storage Management metadata. You can use the following formula to calculate the additional disk space requirements (in MB):

   15 + (2 * number_of_disks) + (126 * number_of_Automatic_Storage_Management_instances)

   For example, for a four-node RAC installation, using three disks in a high redundancy disk group, you require an additional 525 MB of disk space:

   15 + (2 * 3) + (126 * 4) = 525

   If an Automatic Storage Management instance is already running on the system, then you can use an existing disk group to meet these storage requirements. If necessary, you can add disks to an existing disk group during the installation.

   The following section describes how to identify existing disk groups and determine the free disk space that they contain.

4. Optionally, identify failure groups for the Automatic Storage Management disk group devices.

   
   

   Note: You need to complete this step only if you intend to use an installation method that runs Database Configuration Assistant in interactive mode, for example, if you intend to choose the Custom installation type or the Advanced database configuration option. Other installation types do not enable you to specify failure groups.

   
   

   If you intend to use a normal or high redundancy disk group, then you can further protect your database against hardware failure by associating a set of disk devices in a custom failure group. By default, each device comprises its own failure group. However, if two disk devices in a normal redundancy disk group are attached to the same SCSI controller, then the disk group becomes unavailable if the controller fails. The controller in this example is a single point of failure.

   To protect against failures of this type, you could use two SCSI controllers, each with two disks, and define a failure group for the disks attached to each controller. This configuration would enable the disk group to tolerate the failure of one SCSI controller.

   
   

   Note: If you define custom failure groups, then you must specify a minimum of two failure groups for normal redundancy disk groups and three failure groups for high redundancy disk groups.

   
   

5. If you are sure that a suitable disk group does not exist on the system, then install or identify appropriate disk devices to add to a new disk group. Use the following guidelines when identifying appropriate disk devices:

   • All of the devices in an Automatic Storage Management disk group should be the same size and have the same performance characteristics.

   • Do not specify more than one partition on a single physical disk as a disk group device. Automatic Storage Management expects each disk group device to be on a separate physical disk.

   • Although you can specify a logical volume as a device in an Automatic Storage Management disk group, Oracle does not recommend their use. Logical volume managers can hide the physical disk architecture, preventing Automatic Storage Management from optimizing I/O across the physical devices. They are not supported with RAC.

   
   

   See Also: The "Configuring Disks for Automatic Storage Management" section for information about completing this task

   
   

3.5.2 Using an Existing Automatic Storage Management Disk Group

If you want to store either database or recovery files in an existing Automatic Storage Management disk group, then you have the following choices, depending on the installation method that you select:

• If you select an installation method that runs Database Configuration Assistant in interactive mode (for example, by choosing the Advanced database configuration option), then you can decide whether you want to create a disk group, or to use an existing one.

  The same choice is available to you if you use Database Configuration Assistant after the installation to create a database.

• If you select an installation method that runs Database Configuration Assistant in noninteractive mode, then you must choose an existing disk group for the new database; you cannot create a disk group. However, you can add disk devices to an existing disk group if it has insufficient free space for your requirements.

To determine if an existing Automatic Storage Management disk group exists, or to determine if there is sufficient disk space in a disk group, you can use Oracle Enterprise Manager Grid Control or Database Control. Alternatively, you can use the following procedure:

1. View the contents of the oratab file to determine if an Automatic Storage Management instance is configured on the system:

   $ more /etc/oratab
   
   

   If an Automatic Storage Management instance is configured on the system, then the oratab file should contain a line similar to the following:

   +ASM2:oracle_home_path
   
   

   In this example, +ASM2 is the system identifier (SID) of the Automatic Storage Management instance, with the node number appended, and oracle_home_path is the Oracle home directory where it is installed. By convention, the SID for an Automatic Storage Management instance begins with a plus sign.

2. Set the ORACLE_SID and ORACLE_HOME environment variables to specify the appropriate values for the Automatic Storage Management instance that you want to use.

3. Connect to the Automatic Storage Management instance as the SYS user with SYSDBA privilege and start the instance if necessary:

   $ $ORACLE_HOME/bin/sqlplus "SYS/SYS_password as SYSDBA"
   SQL> STARTUP
   
   

4. Enter the following command to view the existing disk groups, their redundancy level, and the amount of free disk space in each one:

   SQL> SELECT NAME,TYPE,TOTAL_MB,FREE_MB FROM V$ASM_DISKGROUP;
   
   

5. From the output, identify a disk group with the appropriate redundancy level and note the free space that it contains.

6. If necessary, install or identify the additional disk devices required to meet the storage requirements listed in the previous section.

   
   

   Note: If you are adding devices to an existing disk group, then Oracle recommends that you use devices that have the same size and performance characteristics as the existing devices in that disk group.

   
   

3.5.3 Configuring Disks for Automatic Storage Management with ASMLIB

The Automatic Storage Management library driver (ASMLIB) simplifies the configuration and management of the disk devices by eliminating the need to rebind raw devices used with ASM each time the system is restarted.

A disk that is configured for use with Automatic Storage Management is known as a candidate disk.

If you intend to use Automatic Storage Management for database storage for Linux, then Oracle recommends that you install the ASMLIB driver and associated utilities, and use them to configure candidate disks.

To use the Automatic Storage Management library driver (ASMLIB) to configure Automatic Storage Management devices, complete the following tasks.

• Installing and Configuring the Automatic Storage Management Library Driver Software

• Configuring the Disk Devices to Use the Automatic Storage Management Library Driver

• Administering the Automatic Storage Management Library Driver and Disks

Installing and Configuring the Automatic Storage Management Library Driver Software

To install and configure the ASMLIB driver software, follow these steps:

1. Enter the following command to determine the kernel version and architecture of the system:

   # uname -rm
   
   

2. If necessary, download the required ASMLIB packages from the OTN Web site:

   http://www.oracle.com/technology/tech/linux/asmlib/index.html
   
   

   
   

   Note: ASMLIB driver packages for some kernel versions are available in the Oracle Clusterware directory on the 10g Release 2 (10.2) DVD-ROM, in the crs/RPMS/asmlib directory. However, Oracle recommends that you check the OTN Web site for the most up-to-date packages.

   
   

   You must install the following packages, where version is the version of the ASMLIB driver, arch is the system architecture, and kernel is the version of the kernel that you are using:

   oracleasm-support-version.arch.rpm
   oracleasm-kernel-version.arch.rpm
   oracleasmlib-version.arch.rpm
   
   

3. Switch user to the root user:

   $ su -
   
   

4. Enter a command similar to the following to install the packages:

   # rpm -Uvh oracleasm-support-version.arch.rpm \
              oracleasm-kernel-version.arch.rpm \
              oracleasmlib-version.arch.rpm
   
   

   For example, if you are using the Red Hat Enterprise Linux AS 4 enterprise kernel on an AMD64 system, then enter a command similar to the following:

   # rpm -Uvh oracleasm-support-2.0.0-1.i386.rpm \
              oracleasmlib-2.0.0-1.x86_64.rpm \
              oracleasm-2.6.9-11.EL-2.0.0-1.x86_64.rpm
   
   

5. Enter the following command to run the oracleasm initialization script with the configure option:

   # /etc/init.d/oracleasm configure
   
   

6. Enter the following information in response to the prompts that the script displays:

   Prompt	Suggested Response
   Default user to own the driver interface:	Specify the Oracle software owner user (typically, oracle).
   Default group to own the driver interface:	Specify the OSDBA group (typically dba).
   Start Oracle Automatic Storage Management Library driver on boot (y/n):	Enter y to start the Oracle Automatic Storage Management library driver when the system starts.

   
   

   The script completes the following tasks:

   • Creates the /etc/sysconfig/oracleasm configuration file

   • Creates the /dev/oracleasm mount point

   • Loads the oracleasm kernel module

   • Mounts the ASMLIB driver file system

     
     

     Note: The ASMLIB driver file system is not a regular file system. It is used only by the Automatic Storage Management library to communicate with the Automatic Storage Management driver.

     
     

7. Repeat this procedure on all nodes in the cluster where you want to install Oracle Real Application Clusters.

Configuring the Disk Devices to Use the Automatic Storage Management Library Driver

To configure the disk devices that you want to use in an Automatic Storage Management disk group, follow these steps:

1. If you intend to use IDE, SCSI, or RAID devices in the Automatic Storage Management disk group, then follow these steps:

   1. If necessary, install or configure the shared disk devices that you intend to use for the disk group and restart the system.

   2. To identify the device name for the disks that you want to use, enter the following command:

      # /sbin/fdisk -l
      
      

      Depending on the type of disk, the device name can vary:

      Disk Type	Device Name Format	Description
      IDE disk	/dev/hdxn	In this example, x is a letter that identifies the IDE disk and n is the partition number. For example, /dev/hda is the first disk on the first IDE bus.
      SCSI disk	/dev/sdxn	In this example, x is a letter that identifies the SCSI disk and n is the partition number. For example, /dev/sda is the first disk on the first SCSI bus.
      RAID disk	/dev/rd/cxdypz /dev/ida/cxdypz	Depending on the RAID controller, RAID devices can have different device names. In the examples shown, x is a number that identifies the controller, y is a number that identifies the disk, and z is a number that identifies the partition. For example, /dev/ida/c0d1 is the second logical drive on the first controller.

      
      

      To include devices in a disk group, you can specify either whole-drive device names or partition device names.

      
      

      Note: Oracle recommends that you create a single whole-disk partition on each disk that you want to use.

      
      

   3. Use either fdisk or parted to create a single whole-disk partition on the disk devices that you want to use.

2. Enter a command similar to the following to mark a disk as an Automatic Storage Management disk:

   # /etc/init.d/oracleasm createdisk DISK1 /dev/sdb1
   
   

   In this example, DISK1 is a name that you want to assign to the disk.

   
   

   Note: The disk names that you specify can contain uppercase letters, numbers, and the underscore character. They must start with an uppercase letter. If you are using a multi-pathing disk driver with Automatic Storage Management, then make sure that you specify the correct logical device name for the disk.

   
   

3. To make the disk available on the other nodes in the cluster, enter the following command as root on each node:

   # /etc/init.d/oracleasm scandisks
   
   

   This command identifies shared disks attached to the node that are marked as Automatic Storage Management disks.

Administering the Automatic Storage Management Library Driver and Disks

To administer the Automatic Storage Management library driver and disks, use the oracleasm initialization script with different options, as follows:

configure

# /etc/init.d/oracleasm configure

enable
disable

# /etc/init.d/oracleasm enable

start
stop
restart

# /etc/init.d/oracleasm restart

createdisk

# /etc/init.d/oracleasm createdisk DISKNAME devicename

deletedisk

# /etc/init.d/oracleasm deletedisk DISKNAME

querydisk

# /etc/init.d/oracleasm querydisk {DISKNAME | devicename}

listdisks

# /etc/init.d/oracleasm listdisks

scandisks

# /etc/init.d/oracleasm scandisks

When you have completed creating and configuring Automatic Storage Management, with ASMLIB, proceed to Chapter 4, "Installing Oracle Clusterware".

3.5.4 Configuring Database File Storage on ASM and Raw Devices

To configure disks for Automatic Storage Management (ASM) using raw devices, complete the following tasks:

1. To use ASM with raw partitions, you must create sufficient partitions for your data files, and then bind the partitions to raw devices. To do this, follow the instructions provided for Oracle Clusterware in the section "Configuring Storage for Oracle Clusterware Files on Raw Devices".

2. Make a list of the raw device names you create for the data files, and have the list available during database installation.

When you have completed creating and configuring ASM with raw partitions, proceed to Chapter 4, "Installing Oracle Clusterware".

3.6.1 Database File Restrictions for Logical Volume Manager on Linux

The procedures contained in this section describe how to create raw partitions for Oracle Clusterware and database file storage. Although Red Hat Enterprise Linux 3 and SUSE Linux Enterprise Server provide a Logical Volume Manager (LVM), this LVM is not cluster-aware. For this reason, on x86, Oracle does not support the use of logical volumes with RAC for either Oracle Clusterware or database files.

3.6.2 Identifying Required Raw Partitions for Database Files

Table 3-5 lists the number and size of the raw partitions that you must configure for database files.

3.6.3 Creating Required Raw Partitions for Database Files on IDE, SCSI, or RAID Devices

If you intend to use IDE, SCSI, or RAID devices for the database raw devices, then follow these steps:

1. If necessary, install or configure the shared disk devices that you intend to use for the raw partitions and restart the system.

   
   

   Note: Because the number of partitions that you can create on a single device is limited, you might need to create the required raw partitions on more than one device.

   
   

2. To identify the device name for the disks that you want to use, enter the following command:

   # /sbin/fdisk -l
   
   

   Depending on the type of disk, the device name can vary:

   Disk Type	Device Name Format	Description
   IDE disk	/dev/hdxn	In this example, x is a letter that identifies the IDE disk and n is the partition number. For example, /dev/hda is the first disk on the first IDE bus.
   SCSI disk	/dev/sdxn	In this example, x is a letter that identifies the SCSI disk and n is the partition number. For example, /dev/sda is the first disk on the first SCSI bus.
   RAID disk	/dev/rd/cxdypz /dev/ida/cxdypz	Depending on the RAID controller, RAID devices can have different device names. In the examples shown, x is a number that identifies the controller, y is a number that identifies the disk, and z is a number that identifies the partition. For example, /dev/ida/c0d1 is the second logical drive on the first controller.

   
   

   You can create the required raw partitions either on new devices that you added or on previously partitioned devices that have unpartitioned free space. To identify devices that have unpartitioned free space, examine the start and end cylinder numbers of the existing partitions and determine if the device contains unused cylinders.

3. To create raw partitions on a device, enter a command similar to the following:

   # /sbin/fdisk devicename
   
   

   Use the following guidelines when creating partitions:

   • Use the p command to list the partition table of the device.

   • Use the n command to create a partition.

   • After you have created the required partitions on this device, use the w command to write the modified partition table to the device.

   • Refer to the fdisk man page for more information about creating partitions.

3.6.4 Binding Partitions to Raw Devices for Database Files

After you have created the required partitions for database files, you must bind the partitions to raw devices on every node. However, you must first determine what raw devices are already bound to other devices. The procedure that you must follow to complete this task varies, depending on the Linux distribution that you are using:

• Red Hat:

  1. To determine what raw devices are already bound to other devices, enter the following command on every node:

     # /usr/bin/raw -qa
     
     

     Raw devices have device names in the form /dev/raw/rawn, where n is a number that identifies the raw device.

     For each device that you want to use, identify a raw device name that is unused on all nodes.

  2. Open the /etc/sysconfig/rawdevices file in any text editor and add a line similar to the following for each partition that you created:

     /dev/raw/raw1 /dev/sdb1
     
     

     Specify an unused raw device for each partition.

  3. For each raw device that you specified in the rawdevices file, enter commands similar to the following to set the owner, group, and permissions on the device file:

     # chown oracle:dba /dev/raw/rawn
     # chmod 660 /dev/raw/rawn
     
     

  4. To bind the partitions to the raw devices, enter the following command:

     # /sbin/service rawdevices restart
     
     

     The system automatically binds the devices listed in the rawdevices file when it restarts.

  5. Repeat step 2 through step 4 on the other nodes in the cluster.

• SUSE:

  1. To determine what raw devices are already bound to other devices, enter the following command on every node:

     # /usr/sbin/raw -qa
     
     

     Raw devices have device names in the form /dev/raw/rawn, where n is a number that identifies the raw device.

     For each device that you want to use, identify a raw device name that is unused on all nodes.

  2. Open the /etc/raw file in any text editor and add a line similar to the following to associate each partition with an unused raw device:

     raw1:sdb1
     
     

  3. For each raw device that you specified in the /etc/raw file, enter commands similar to the following to set the owner, group, and permissions on the device file:

     # chown oracle:dba /dev/raw/rawn
     # chmod 660 /dev/raw/rawn
     
     

  4. To bind the partitions to the raw devices, enter the following command:

     # /etc/init.d/raw start
     
     

  5. To ensure that the raw devices are bound when the system restarts, enter the following command:

     # /sbin/chkconfig raw on
     
     

  6. Repeat step 2 through step 5 on the other nodes in the cluster.

3.6.5 Creating the Database Configuration Assistant Raw Device Mapping File

To allow Database Configuration Assistant to identify the appropriate raw device for each database file, you must create a raw device mapping file, as follows:

1. Set the ORACLE_BASE environment variable to specify the Oracle base directory that you identified or created previously:

   • Bourne, Bash, or Korn shell:

     $ ORACLE_BASE=/u01/app/oracle ; export ORACLE_BASE
     
     

   • C shell:

     % setenv ORACLE_BASE /u01/app/oracle
     
     

2. Create a database file subdirectory under the Oracle base directory and set the appropriate owner, group, and permissions on it:

   # mkdir -p $ORACLE_BASE/oradata/dbname
   # chown -R oracle:oinstall $ORACLE_BASE/oradata
   # chmod -R 775 $ORACLE_BASE/oradata
   
   

   In this example, dbname is the name of the database that you chose previously.

3. Change directory to the $ORACLE_BASE/oradata/dbname directory.

4. Edit the dbname_raw.conf file in any text editor to create a file similar to the following:

   
   

   Note: The following example shows a sample mapping file for a two-instance RAC cluster.

   
   

   system=/dev/raw/raw1
   sysaux=/dev/raw/raw2
   example=/dev/raw/raw3
   users=/dev/raw/raw4
   temp=/dev/raw/raw5
   undotbs1=/dev/raw/raw6
   undotbs2=/dev/raw/raw7
   redo1_1=/dev/raw/raw8
   redo1_2=/dev/raw/raw9
   redo2_1=/dev/raw/raw10
   redo2_2=/dev/raw/raw11
   control1=/dev/raw/raw12
   control2=/dev/raw/raw13
   spfile=/dev/raw/raw14
   pwdfile=/dev/raw/raw15
   
   

   Use the following guidelines when creating or editing this file:

   • Each line in the file must have the following format:

     database_object_identifier=raw_device_path
     
     

   • For a single-instance database, the file must specify one automatic undo tablespace data file (undotbs1), and at least two redo log files (redo1_1, redo1_2).

   • For a RAC database, the file must specify one automatic undo tablespace data file (undotbsn) and two redo log files (redon_1, redon_2) for each instance.

   • Specify at least two control files (control1, control2).

   • To use manual instead of automatic undo management, specify a single rollback segment tablespace data file (rbs) instead of the automatic undo management tablespace data files.

5. Save the file, and note the file name that you specified.

6. If you are using raw devices for database storage, then set the DBCA_RAW_CONFIG environment variable to specify the full path to the raw device mapping file:

   Bourne, Bash, or Korn shell:

   $ DBCA_RAW_CONFIG=$ORACLE_BASE/oradata/dbname/dbname_raw.conf
   $ export DBCA_RAW_CONFIG
   
   

   C shell:

   $ setenv DBCA_RAW_CONFIG=$ORACLE_BASE/oradata/dbname/dbname_raw.conf