2 Preinstallation Tasks

2.4.1 Configuring Name Resolution

When you run Oracle Universal Installer, an error may occur if name resolution is not set up. To avoid this error, before you begin installation, you must ensure that host names are resolved only through the /etc/hosts file.

To ensure that host names are resolved only through the /etc/hosts file:

1. Verify that the /etc/hosts file is used for name resolution. You can do this by checking the hosts file entry in the nsswitch.conf file as follows:

   # cat /etc/nsswitch.conf | grep hosts
   
   

   The output of this command should contain an entry for files.

2. Verify that the host name has been set by using the hostname command as follows:

   # hostname
   
   

   The output of this command should be similar to the following:

   myhost.mycomputer.com
   
   

3. Verify that the domain name has not been set dynamically by using the domainname command as follows:

   # domainname
   
   

   This command should not return any results.

4. Verify that the hosts file contains the fully qualified host name by using the following command:

   # cat /etc/hosts | grep `eval hostname`
   
   

   The output of this command should contain an entry for the fully qualified host name and for localhost.

   For example:

   192.168.100.16    myhost.us.mycompany.com   myhost
   127.0.0.1         localhost                 localhost.localdomain
   
   

   If the hosts file does not contain the fully qualified host name, then open the file and make the required changes in it.

2.4.2 Installing on DHCP Computers

Dynamic Host Configuration Protocol (DHCP) assigns dynamic IP addresses on a network. Dynamic addressing enables a computer to have a different IP address each time it connects to the network. In some cases, the IP address can change while the computer is still connected. You can have a mixture of static and dynamic IP addressing in a DHCP system.

In a DHCP setup, the software tracks IP addresses, which simplifies network administration. This lets you add a new computer to the network without having to manually assign that computer a unique IP address.

2.4.3 Installing on Multihomed Computers

You can install Oracle Database on a multihomed computer. A multihomed computer is associated with multiple IP addresses. This is typically achieved by having multiple network cards on the computer. Each IP address is associated with a host name. In addition, you can set up aliases for the host name. By default, Oracle Universal Installer uses the ORACLE_HOSTNAME environment variable setting to find the host name. If ORACLE_HOSTNAME is not set and you are installing on a computer that has multiple network cards, then Oracle Universal Installer determines the host name by using the first entry in the /etc/hosts file.

Clients must be able to access the computer either by using this host name or by using aliases for this host name. To verify this, ping the host name from the client computers using the short name (hostname only) and the full name (hostname and domain name). Both tests must be successful.

Setting the ORACLE_HOSTNAME Environment Variable

Use the following procedure to set the ORACLE_HOSTNAME environment variable.

For example, if the fully qualified host name is somehost.us.acme.com, then enter one of the following commands:

Bourne, Bash, or Korn shell:

$ ORACLE_HOSTNAME=somehost.us.acme.com
$ export ORACLE_HOSTNAME

C shell:

% setenv ORACLE_HOSTNAME somehost.us.acme.com

2.4.4 Installing on Computers with Multiple Aliases

A computer with multiple aliases is registered with the naming service under a single IP but with multiple aliases. The naming service resolves any of those aliases to the same computer. Before installing Oracle Database on such a computer, set the ORACLE_HOSTNAME environment variable to the computer whose host name you want to use.

2.4.5 Installing on Non-Networked Computers

You can install Oracle Database on a non-networked computer. If the computer, such as a laptop, is configured for DHCP and you plan to connect the computer to the network after the Oracle Database installation, then use the ping command on the computer on which you want to install the database to check if the computer can connect to itself. Perform this step by first using only the host name and then using the fully qualified name, which should be in the /etc/hosts file.

If the ping command fails, then contact your network administrator.

Connecting the Computer to the Network after Installation

If you connect the computer to a network after installation, then the Oracle Database instance on your computer can work with other instances on the network. The computer can use a static IP or DHCP, depending on the network to which you are connected.

2.5.1 Creating the Oracle Inventory Group

You must create the Oracle Inventory group if it does not already exist. The following subsections describe how to determine the Oracle Inventory group name, if it exists, and how to create it if necessary.

Determining Whether the Oracle Inventory Group Exists

When you install Oracle software on the system for the first time, Oracle Universal Installer creates the oraInst.loc file. This file identifies the name of the Oracle Inventory group and the path of the Oracle Inventory directory.

To determine whether the Oracle Inventory group exists, enter the following command:

# more /var/opt/oracle/oraInst.loc

If the output of this command shows the oinstall group name, then the group already exists.

If the oraInst.loc file exists, then the output from this command is similar to the following:

inventory_loc=/u01/app/oracle/oraInventory
inst_group=oinstall

The inst_group parameter shows the name of the Oracle Inventory group, oinstall.

Creating the Oracle Inventory Group

If the oraInst.loc file does not exist, then create the Oracle Inventory group by entering the following command:

# /usr/sbin/groupadd oinstall

2.5.2 Creating the OSDBA Group

You must create an OSDBA group in the following circumstances:

• An OSDBA group does not exist, for example, if this is the first installation of Oracle Database software on the system

• An OSDBA group exists, but you want to give a different group of operating system users database administrative privileges in a new Oracle installation

If the OSDBA group does not exist or if you require a new OSDBA group, then create it as follows. In the following command, use the group name dba unless a group with that name already exists.

# /usr/sbin/groupadd dba

2.5.3 Creating an OSOPER Group (Optional)

Create an OSOPER group only if you want to identify a group of operating system users with a limited set of database administrative privileges (SYSOPER operator privileges). For most installations, it is sufficient to create only the OSDBA group. If you want to use an OSOPER group, then you must create it in the following circumstances:

• If an OSOPER group does not exist, for example, if this is the first installation of Oracle Database software on the system

• If an OSOPER group exists, but you want to give a different group of operating system users database operator privileges in a new Oracle installation

If you require a new OSOPER group, then create it as follows. In the following command, use the group name oper unless a group with that name already exists.

# /usr/sbin/groupadd oper

2.5.4 Creating the Oracle Software Owner User

You must create an Oracle software owner user in the following circumstances:

• If an Oracle software owner user does not exist, for example, if this is the first installation of Oracle software on the system

• If an Oracle software owner user exists, but you want to use a different operating system user, with different group membership, to give database administrative privileges to those groups in a new Oracle Database installation

# id oracle

uid=440(oracle) gid=200(oinstall) groups=201(dba),202(oper)

# /usr/sbin/usermod -g oinstall -G dba[,oper] oracle

2.5.5 Verifying that the User nobody Exists

Before installing the software, perform the following procedure to verify that the nobody user exists on the system:

1. To determine whether the user exists, enter the following command:

   # id nobody
   
   

   If this command displays information about the nobody user, then you do not have to create that user.

2. If the nobody user does not exist, then enter the following command to create it:

   # /usr/sbin/useradd nobody
   

2.7.1 Oracle Base Directory

The Oracle base directory is a top-level directory for Oracle software installations. It is analogous to the C:\Oracle directory used for Oracle software installations on Microsoft Windows systems. On Linux systems, the Optimal Flexible Architecture (OFA) guidelines recommend that you use a path similar to the following for the Oracle base directory:

/mount_point/app/oracle_sw_owner

In this example:

• mount_point is the mount point directory for the file system that will contain the Oracle software.

  The examples in this guide use /u01 for the mount point directory. However, you could choose another mount point directory, such as /oracle or /opt/oracle.

• oracle_sw_owner is the operating system user name of the Oracle software owner, for example oracle.

You can use the same Oracle base directory for more than one installation or you can create separate Oracle base directories for different installations. If different operating system users install Oracle software on the same system, then each user must create a separate Oracle base directory. The following example Oracle base directories could all exist on the same system:

/u01/app/oracle
/u01/app/orauser
/opt/oracle/app/oracle

The following sections describe how to identify existing Oracle base directories that may be suitable for your installation and how to create an Oracle base directory if necessary.

Regardless of whether you create an Oracle base directory or decide to use an existing one, you must set the ORACLE_BASE environment variable to specify the full path to this directory.

2.7.2 Oracle Inventory Directory

The Oracle Inventory directory (oraInventory) stores an inventory of all software installed on the system. It is required by, and shared by, all Oracle software installations on a single system. The first time you install Oracle software on a system, Oracle Universal Installer prompts you to specify the path to this directory. then Oracle recommends that you choose the following path:

oracle_base/oraInventory

Oracle Universal Installer creates the directory that you specify and sets the correct owner, group, and permissions for it. You do not need to create it.

2.7.3 Oracle Home Directory

The Oracle home directory is the directory where you choose to install the software for a particular Oracle product. You must install different Oracle products, or different releases of the same Oracle product, in separate Oracle home directories. When you run Oracle Universal Installer, it prompts you to specify the path to this directory, as well as a name that identifies it. The directory that you specify must be a subdirectory of the Oracle base directory. Oracle recommends that you specify a path similar to the following for the Oracle home directory:

oracle_base/product/10.2.0/db_1

Oracle Universal Installer creates the directory path that you specify under the Oracle base directory. It also sets the correct owner, group, and permissions on it. You do not need to create this directory.

2.8.1 Identifying an Existing Oracle Base Directory

Existing Oracle base directories may not have paths that comply with OFA guidelines. However, if you identify an existing Oracle Inventory directory or existing Oracle home directories, then you can usually identify the Oracle base directories, as follows:

• Identifying an existing Oracle Inventory directory

  Enter the following command to view the contents of the oraInst.loc file:

  # more /var/opt/oracle
  
  

  If the oraInst.loc file exists, then the output from this command is similar to the following:

  inventory_loc=/u01/app/oracle/oraInventory
  inst_group=oinstall
  
  

  The inventory_loc parameter identifies the Oracle Inventory directory (oraInventory). The parent directory of the oraInventory directory is typically an Oracle base directory. In the previous example, /u01/app/oracle is an Oracle base directory.

• Identifying existing Oracle home directories

  Enter the following command to view the contents of the oratab file:

  # more /etc/oratab
  
  

  If the oratab file exists, then it contains lines similar to the following:

  *:/u03/app/oracle/product/10.2.0/db_1:N
  *:/opt/orauser/infra_904:N
  *:/oracle/9.2.0:N
  
  

  The directory paths specified on each line identify Oracle home directories. Directory paths that end with the user name of the Oracle software owner that you want to use are valid choices for an Oracle base directory. If you intend to use the oracle user to install the software, then you could choose one of the following directories from the previous example:

  /u03/app/oracle
  /oracle
  

  
  

  Note: If possible, choose a directory path similar to the first (/u03/app/oracle). This path complies with the OFA guidelines.

  
  

Before deciding to use an existing Oracle base directory for this installation, ensure that it satisfies the following conditions:

• It should not be on the same file system as the operating system.

• It must have sufficient free disk space, as follows:

  Requirement	Free Disk Space
  The Oracle base directory will contain only software files.	Up to 3 GB
  The Oracle base directory will contain both software and database files (not recommended for production databases).	Up to 4 GB

  
  

  To determine the free disk space on the file system where the Oracle base directory is located, enter the following command:

  • # df -h oracle_base_path
    
    

To continue:

• If an Oracle base directory exists and you want to use it, then refer to the "Choosing a Storage Option for Oracle Database and Recovery Files" section.

  When you configure the oracle user's environment later in this chapter, set the ORACLE_BASE environment variable to specify the directory you chose.

• If an Oracle base directory does not exist on the system or if you want to create an Oracle base directory, then refer to the following section.

2.8.2 Creating an Oracle Base Directory

Before you create an Oracle base directory, you must identify an appropriate file system with sufficient free disk space, as follows:

To identify an appropriate file system:

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

2. From the display, identify a file system that has appropriate free space.

   The file system that you identify can be a local file system, a cluster file system, or an NFS file system on a certified NAS device.

3. Note the name of the mount point directory for the file system that you identified.

To create the Oracle base directory and specify the correct owner, group, and permissions for it:

1. Enter commands similar to the following to create the recommended subdirectories in the mount point directory that you identified and set the appropriate owner, group, and permissions on them:

   # mkdir -p /mount_point/app/oracle_sw_owner
   # chown -R oracle:oinstall /mount_point/app/oracle_sw_owner
   # chmod -R 775 /mount_point/app/oracle_sw_owner
   
   

   For example, if the mount point you identify is /u01 and oracle is the user name of the Oracle software owner, then the recommended Oracle base directory path is as follows:

   /u01/app/oracle
   
   

2. When you configure the oracle user's environment later in this chapter, set the ORACLE_BASE environment variable to specify the Oracle base directory that you have created.

2.10.1 Guidelines for Placing Oracle Database Files on a File System

If you choose to place the Oracle Database files on a file system, then use the following guidelines when deciding where to place them:

• The default path suggested by Oracle Universal Installer for the database file directory is a subdirectory of the Oracle base directory.

• You can choose either a single file system or more than one file system to store the database files:

  • If you want to use a single file system, then choose a file system on a physical device that is dedicated to the database.

    For best performance and reliability, choose a RAID device or a logical volume on more than one physical device and implement the stripe-and-mirror-everything (SAME) methodology.

  • If you want to use more than one file system, then choose file systems on separate physical devices that are dedicated to the database.

    This method enables you to distribute physical I/O and create separate control files on different devices for increased reliability. It also enables you to fully implement the OFA guidelines described in Appendix C, "Optimal Flexible Architecture". You must choose either the Advanced database creation option or the Custom installation type during the installation to implement this method.

• If you intend to create a preconfigured database during the installation, then the file system (or file systems) that you choose must have at least 1.2 GB of free disk space.

  For production databases, you must estimate the disk space requirement depending on the use that you want to make of the database.

• For optimum performance, the file systems that you choose should be on physical devices that are used only by the database.

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

2.10.2 Guidelines for Placing Oracle Recovery Files on a File System

If you choose to place the Oracle recovery files on a file system, then use the following guidelines when deciding where to place them:

• To prevent disk failure from making both the database files and the recovery files unavailable, place the recovery files in a file system on a different physical disk from the database files.

  
  

  Note: Alternatively, use an Automatic Storage Management disk group for both data and recovery files.

  
  

• • The file system that you choose should have at least 2 GB of free disk space.

    The disk space requirement is the default disk quota configured for the flash recovery area (specified by the DB_RECOVERY_FILE_DEST_SIZE initialization parameter).

    If you choose the Custom installation type or the Advanced database configuration option, then you can specify a different disk quota value. After you create the database, you can also use Oracle Enterprise Manager Grid Control or Database Control to specify a different value.

    
    

    See Also: Oracle Database Backup and Recovery Basics for more information about sizing the flash recovery area

    
    

• The default path suggested by Oracle Universal Installer for the flash recovery area is a subdirectory of the Oracle base directory.

  This default location is not recommended for production databases.

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

2.10.3 Creating Required Directories

To create directories for the Oracle database, or recovery files on separate file systems to the Oracle base directory:

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

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

   File Type	File System Requirements
   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 2.4 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.

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

4. Enter 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:

   • 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
     
     

5. If you also want to use Automatic Storage Management or raw devices for storage, then refer to one of the following sections:

   • Preparing Disk Groups for an Automatic Storage Management Installation

   • Configuring Raw Partitions or Raw Logical Volumes

2.11.1 General Steps for Configuring Automatic Storage Management

The following are the general steps to configure Automatic Storage Management:

1. Identify the storage requirements of the site.

2. Optionally, use an existing Automatic Storage Management disk group.

3. If you are creating a new Automatic Storage Management disk group, create partitions for DAS or SAN disks.

4. Use one of the following methods to complete the Automatic Storage Management configuration:

   • If you plan to install Oracle Database using interactive mode, Oracle Universal Installer prompts you for the Automatic Storage Management disk configuration information during the installation.

   • If you plan to install Oracle Database using noninteractive mode, you will need to manually configure the disks before performing the installation.

2.11.2 Step 1: Identifying Storage Requirements for Automatic Storage Management

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

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 data files and recovery files. You can use the file system for one file type and Automatic Storage Management for the other. If you plan to use Automatic Storage Management for both data files and recovery files, then you should create separate Automatic Storage Management disk groups for the data files and the recovery files.

   
   

   If you plan to enable automated backups during the installation, then 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 Oracle Database Configuration Assistant in interactive mode, by choosing the Advanced database configuration option for example, then you can decide whether you want to use the same Automatic Storage Management disk group for database files and recovery files, or you can choose to use different disk groups for each file type. Ideally, you should create separate Automatic Storage Management disk groups for data files and for recovery files.

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

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

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

   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 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.

     If you select this option, Automatic Storage Management does not mirror the contents of the disk group. Choose this redundancy level under any one of the following conditions:

     • When the disk group contains devices, such as RAID devices, that provide their own data protection

     • The use of the database does not require uninterrupted access to data, for example, in a development environment where you have a suitable backup strategy

   • Normal redundancy

     In a normal redundancy disk group, by default Automatic Storage Management uses two-way mirroring for datafiles and three-way mirroring for control files, to increase performance and reliability. Alternatively, you can use two-way mirroring or no mirroring. A normal redundancy disk group requires a minimum of two failure groups (or two disk devices) if you are using two-way mirroring. 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 use normal redundancy disk groups.

   • High redundancy

     The contents of the disk group are three-way mirrored by default. To create a disk group with high redundancy, you must specify at least 3 failure groups (a minimum of 3 devices).

     Although high-redundancy disk groups provide a high level of data protection, you must consider the higher cost of additional storage devices before deciding to use this redundancy level.

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 the installation:

   Redundancy Level	Minimum Number of Disks	Data 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

   
   

   If an ASM 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 step 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 perform this step only if you intend to use an installation method that runs Oracle 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 the database against hardware failure by associating a set of disk devices in a custom failure group. By default, each device comprises its 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 avoid failures of this type, you can 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. Apply the following guidelines when identifying appropriate disk devices:

   • All 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 its use. Logical volume managers can hide the physical disk architecture. This would prevent Automatic Storage Management from optimizing I/O across the physical devices.

   
   

   See Also: "Step 4: Configuring Disks for Automatic Storage Management" for information about completing this task

   
   

2.11.3 Step 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 Oracle Database Configuration Assistant in interactive mode (for example, choosing the Advanced database configuration option), then you can decide whether you want to create a disk group or use an existing one.

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

• If you select an installation method that runs Oracle 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 whether an existing Automatic Storage Management disk group exists, or to determine whether 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 whether an ASM instance is configured on the system:

   # more /etc/oratab
   
   

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

   +ASM:oracle_home_path:N
   
   

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

2. Open a shell window and temporarily set the ORACLE_SID and ORACLE_HOME environment variables to specify the appropriate values for the ASM instance that you want to use.

   For example, if the Automatic Storage Management SID is named OraDB10g+ASM and is located in the asm subdirectory of the ORACLE_BASE directory, then enter the following commands to create the required settings:

   • Bourne, Bash, or Korn shell:

     $ ORACLE_SID=OraDB10g+ASM
     $ export ORACLE_SID
     $ ORACLE_HOME=/u01/app/oracle/product/10.1.0/asm
     $ export ORACLE_HOME
     
     

   • C shell:

     % setenv ORACLE_SID OraDB10g+ASM
     % setenv ORACLE_HOME /u01/app/oracle/product/10.1.0/asm
     
     

3. By using SQL*Plus, connect to the ASM 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.

   
   

2.11.4 Step 3: Creating DAS or SAN Disk Partitions for Automatic Storage Management

In order to use a DAS or SAN disk in Automatic Storage Management, the disk must have a partition table. Oracle recommends creating exactly one partition for each disk containing the entire disk.

2.11.5 Step 4: Configuring Disks for Automatic Storage Management

Oracle provides an Automatic Storage Management library driver that you can use to simplify the configuration and management of the disk devices that you want to use with Automatic Storage Management. A disk that is configured for Automatic Storage Management is known as a candidate disk.

If you intend to use Automatic Storage Management for database storage on Linux, then Oracle recommends that you install the Automatic Storage Management library driver and associated utilities and use them to configure the devices that you want to include in an Automatic Storage Management disk group. If you do not use the Automatic Storage Management library driver, then you must bind each disk device that you want to use to a raw device. The following sections describe how to configure disks using each method:

• Configuring Disks for Automatic Storage Management Using the Automatic Storage Management Library Driver

• Configuring Disks for Automatic Storage Management Using Raw Devices

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

2.12.1 Using Raw Logical Volumes

The procedures in the following sections describe how to create raw partitions for Oracle Database file storage. You can use raw partitions for database file storage on all supported Linux distributions.

Alternatively, on Red Hat Enterprise Linux 3 and SUSE Linux Enterprise Server, you can use Logical Volume Manager (LVM) to create logical volumes of the required size and use them instead of raw partitions. Using LVM can provide benefits when used as the method for storing Oracle Database files on raw devices. For example, LVM enables you to overcome the limitations on the number of partitions that you can create on a single physical disk.

If you want to use logical volumes instead of raw partitions, then:

1. Create a separate volume group for the Oracle Database files.

   You can use a name such as oracle_vg or dbname_vg for the volume group.

2. Create the required number of logical volumes using the sizes listed in Table 2-1.

   Use a naming convention similar to the following when creating the logical volumes:

   dbname_objectname_raw_sizem
   
   

   For example, you may name the logical volume for the SYSTEM table space (500 MB) in the sales database as follows:

   sales_system_raw_500m
   
   

3. Bind the logical volumes to raw devices as described in the "Binding the Partitions to Raw Devices" section, using the logical volume device name in place of the partition device name.

4. Create the raw device mapping file as described in the "Creating the Oracle Database Configuration Assistant Raw Device Mapping File" section.

2.12.2 Identifying the Required Raw Partitions

Table 2-1 lists the number and size of the raw partitions that you must configure for database files.

2.12.3 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:

1. If necessary, install or configure the 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 may 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
   
   

   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.

2.12.4 Binding the Partitions to Raw Devices

After you have created the required partitions, you must bind the partitions to raw devices. 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:

     # /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.

  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.

• SUSE:

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

     # /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
     
     

2.12.5 Creating the Oracle Database Configuration Assistant Raw Device Mapping File

To enable Oracle 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:

   system=/dev/raw/raw1
   sysaux=/dev/raw/raw2
   example=/dev/raw/raw3
   users=/dev/raw/raw4
   temp=/dev/raw/raw5
   undotbs1=/dev/raw/raw6
   redo1_1=/dev/raw/raw8
   redo1_2=/dev/raw/raw9
   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
     
     

   • The file must specify one automatic undo tablespace data file (undotbs1), and at least two redo log files (redo1_1, redo1_2).

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

   • To use manual instead of automatic undo management, specify a single RBS 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. When you are configuring the oracle user's environment later in this chapter, set the DBCA_RAW_CONFIG environment variable to specify the full path to this file.

To continue, refer to the "Stopping Existing Oracle Processes" section.