2 Preinstallation Tasks

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 using the following command:

   # dscacheutil -configuration
   

   The output of this command must contain /BSD/local.

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

   # hostname
   

   The output of this command must 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 must 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 must 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.

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.

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 if clients are able to access the computer, 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 the following commands:

For Bourne, Bash, or Korn shell:

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

For C shell:

% setenv ORACLE_HOSTNAME somehost.us.acme.com

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 is to be used.

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 the database is to be installed, 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 must 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.

Creating the Oracle Inventory Group

You must create the Oracle Inventory group if it does not 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 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 using either of the following methods:

• Use Workgroup Manager (/Applications/Server/Workgroup Manager) to create a group called oinstall.

• Use command-line utilities to create the Oracle Inventory group:

  1. Enter the following command to list existing groups and group IDs (GIDs):

     # dscl . -list /groups gid name | more
     

  2. Identify an unused GID for the new Oracle Inventory group.

  3. Enter commands similar to the following to create the oinstall group:

     # dscl . -create /groups/oinstall
     # dscl . -append /groups/oinstall gid gid_number
     # dscl . -append /groups/oinstall passwd "*"
     

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 exists.

• Use Workgroup Manager to create a group called dba.

• Use command-line utilities to create the OSDBA group:

  1. Enter the following command to list existing groups and GIDs:

     # dscl . -list /groups gid name | more
     

  2. Identify an unused GID for the new OSDBA group.

  3. Enter commands similar to the following to create the dba group:

     # dscl . -create /groups/dba
     # dscl . -append /groups/dba gid gid_number
     # dscl . -append /groups/dba passwd "*"
     

Creating an OSOPER Group (Optional)

Create an OSOPER group only 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 exists.

• Use Workgroup Manager to create a group called oper.

• Use command-line utilities to create the OSOPER group:

  1. Enter the following command to list existing groups and GIDs:

     # dscl . -list /groups gid name | more
     

  2. Identify an unused GID for the new OSOPER group.

  3. Enter commands similar to the following to create the oper group:

     # dscl . -create /groups/oper
     # dscl . -append /groups/oper gid gid_number
     # dscl . -append /groups/oper passwd "*"
     

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

# id oracle

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

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 Apple Mac OS X (Intel) 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 multiple installations 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.

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. 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.

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, and also 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.

Identifying an Existing Oracle Base Directory

Existing Oracle base directories may not have paths complying 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/oraInst.loc
  

  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 to be used are valid choices for an Oracle base directory. If you intend to use the oracle user to install the software, then choose either 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 must 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 contains only software files.	Up to 3 GB
  The Oracle base directory contains 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.

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.

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.

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 multiple file systems to store the database files:

  • To use a single file system, 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 multiple physical device and implement the stripe-and-mirror-everything (SAME) methodology.

  • To use multiple file systems, 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.

• To create a preconfigured database during the installation, 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 what the database would be used for.

• For optimum performance, the file systems that you choose must 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.

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.

  The file system that you choose must 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.

  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.

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 to be used:

   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 multiple type of files, 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