C Using NAS Devices

If you have a network attached storage (NAS) device that has been certified through the Oracle Storage Compatibility Program (OSCP), you can use it to store the Oracle software, the Oracle database files, or both. This appendix provides guidelines for using a NAS storage device for Oracle software and database files. It includes information about the following:

General Configuration Guidelines for NAS Devices
Choosing Mount Points
Creating Files on a NAS Device for Use with Automatic Storage Management
NFS Mount Options

C.1 General Configuration Guidelines for NAS Devices

Refer to the documentation provided with your NAS device for specific information about how to configure it. In addition, use the following guidelines to ensure that the performance of the Oracle software meets your requirements:

Before using the NAS device for the installation, verify that it is certified. To identify certified devices, check the Oracle Storage Compatibility Program list at the following Web site:

http://www.oracle.com/technology/deploy/availability/htdocs/oscp.html

Note:

The OSCP certifies NAS devices only for single-instance databases. For Oracle Real Application Clusters installations, refer to the Certify page on the OracleMetaLink Web site for information about certified storage solutions, including NAS:

http://metalink.oracle.com

The performance of Oracle software and databases stored on NAS devices depends on the performance of the network connection between the Oracle server and the NAS device.

For this reason, Oracle recommends that you connect the server to the NAS device using a private dedicated network connection, which should be Gigabit Ethernet or better.
For single instance installations (as opposed to RAC installations), you must create a separate Oracle home directory for each installation. Run the software in this Oracle home directory only from the system that you used to install it.

For Oracle Real Application Clusters (RAC) installations, you can use a single Oracle home directory mounted from each node in the cluster. You must mount this Oracle home directory on each node so that it has the same directory path on all nodes.

C.2 Choosing Mount Points

This section provides guidelines on how to choose the mount points for the file systems that you want to use for the Oracle software and database files. The guidelines contained in this section comply with the Optimal Flexible Architecture recommendations.

C.2.1 Choosing Mount Points for Oracle Software Files

Oracle software files are stored in three different directories:

Oracle base directory
Oracle Inventory directory
Oracle home directory

For the first installation of Oracle software on a system, the Oracle base directory, identified by the ORACLE_BASE environment variable, is normally the parent directory for both the Oracle Inventory and Oracle home directories. For example, for a first installation, the Oracle base, Oracle Inventory, and Oracle home directories might have paths similar to the following:

Directory	Path
Oracle base (`$ORACLE_BASE`)	`/u01/app/oracle`
Oracle Inventory	`$ORACLE_BASE/oraInventory`
Oracle home	`$ORACLE_BASE/product/10.2.0/db_1`

For subsequent installations, you can choose to use either the same Oracle base directory or a different one, but every subsequent installation uses the original Oracle Inventory directory. For example, if you use the /u02/app/oracle directory as the Oracle base directory for a new installation, the Oracle Inventory directory continues to be /u01/app/oracle/oraInventory.

To enable you to effectively maintain the Oracle software on a particular system, Oracle recommends that you locate the Oracle Inventory directory only on a local file system, if possible. If you must place the Oracle Inventory directory on a NAS device, create a specific directory for each system, to prevent more than one system from writing to the same Inventory.

Directory-Specific Guidelines

You can use any of the following directories as mount points for NFS file systems used to store Oracle software:

Note:

In the following examples, the paths shown are the defaults if the ORACLE_BASE environment variable is set before you start Oracle Universal Installer.

Oracle base directory or its parents (/u01/app/oracle for example)

If you use the Oracle base directory of one of its parents as a mount point, the default location for all Oracle software and database files will be on that file system. During the installation, you might consider changing the default location of the following directories:
- The Oracle Inventory directory (oracle_base/oraInventory)
  
  Specify a local file system or a host-specific directory on the NFS file system, for example:
```
oracle_base/hostname/oraInventory
```
- The Oracle database file directory (oracle_base/oradata)
  
  You might want to use a different file system for database files, for example, to enable you to specify different mount options or to distribute I/O.
- The Oracle database recovery file directory (oracle_base/flash_recovery_area)
  
  Oracle recommends that you use different file systems for database and recovery files.
If you use this mount point, all Oracle installations that use this Oracle base directory will use the NFS file system.
The product directory (oracle_base/product)

By default, only software files will be located on the NFS file system. You can also use this mount point to install software from different releases, for example:
```
/u01/app/oracle/product/9.2.0
/u01/app/oracle/product/10.2.0/db_1
```
The release directory (oracle_base/product/10.2.0)

By default, only software files will be located on the NFS file system. You can also use this mount point to install different products from the same release, for example:
```
/u01/app/oracle/product/10.2.0/crs
/u01/app/oracle/product/10.2.0/db_1
/u01/app/oracle/product/10.2.0/companion_1
```
The Oracle home directory (oracle_base/product/10.2.0/db_1)

By default, only software files will be located on the NFS file system. This is the most restrictive mount point. You can use it only to install a single release of one product:
```
/u01/app/oracle/product/10.2.0/db_1
```

C.2.2 Choosing Mount Points for Oracle Database and Recovery Files

To store Oracle database or recovery files on a NAS device, you can use different paths depending on whether you want to store files from only one database or from more than one database:

Use the NFS file system for files from more than one database

If you want to store the database files or recovery files from more than one database on the same NFS file systems, use paths or mount points similar to the following:

File Type Path or Mount Point

Database files /u02/oradata

Recovery files /u03/flash_recovery_area

When Oracle Universal Installer prompts you for the data file and the recovery file directories, specify these paths. The Database Configuration Assistant and Enterprise Manager create subdirectories in these directories using the value you specify for the database name (DB_NAME) as the directory name, for example:
```
/u02/oradata/db_name1
/u03/flash_recovery_area/db_name1
```
Use the NFS file system for files from only one database

If you want to store the database files or recovery files for only one database in the NFS file system, you can create mount points similar to the following, where orcl is the name that you want to use for the database:
```
/u02/oradata/orcl
/u03/flash_recovery_area/orcl
```
Specify the directory /u02/oradata when Oracle Universal Installer prompts you for the data file directory and specify the directory /u03/flash_recovery_area when Oracle Universal Installer prompts you for the recovery file location. The orcl directory will be used automatically either by Database Configuration Assistant or by Enterprise Manager.

File Type	Path or Mount Point
Database files	`/u02/oradata`
Recovery files	`/u03/flash_recovery_area`

C.3 Creating Files on a NAS Device for Use with Automatic Storage Management

If you have a certified NAS storage device, you can create zero-padded files in an NFS mounted directory and use those files as disk devices in an Automatic Storage Management disk group. To create these files, follow these steps:

Note:

To use files as disk devices in an Automatic Storage Management disk group, the files must be on an NFS mounted file system. You cannot use files on local file systems.

If necessary, create an exported directory for the disk group files on the NAS device.

Refer to the NAS device documentation for more information about completing this step.
Switch user to root:
```
$ su -
```
Create a mount point directory on the local system:
```
# mkdir -p /mnt/oracleasm
```
To ensure that the NFS file system is mounted when the system reboots, add an entry for the file system in the /etc/fstab mount file.

For more information about editing the mount file for your operating system, refer to the man pages. For more information about recommended mount options, refer to the "NFS Mount Options" section.
Enter a command similar to the following to mount the NFS file system on the local system:
```
# mount /mnt/oracleasm
```
Choose a name for the disk group that you want to create, for example nfsdg.
Create a directory for the files on the NFS file system, using the disk group name as the directory name:
```
# mkdir /mnt/oracleasm/nfsdg
```
Use commands similar to the following to create the required number of zero-padded files in this directory:
```
# dd if=/dev/zero of=/mnt/oracleasm/nfsdg/disk1 bs=1024k count=1000
```
This example creates 1 GB files on the NFS file system. You must create one, two, or three files respectively to create an external, normal, or high redundancy disk group.
Enter the following commands to change the owner, group, and permissions on the directory and files that you created:
```
# chown -R oracle:dba /mnt/oracleasm
# chmod -R 660 /mnt/oracleasm
```
When you are creating the database, edit the Automatic Storage Management disk discovery string to specify a regular expression that matches the file names you created. For example, you might specify a disk discovery string similar to the following:
```
/mnt/oracleasm/nfsdg/*
```

C.4 NFS Mount Options

You must mount NFS volumes used for storing database files with special mount options on the host where the database server is running. When mounting an NFS file system, Oracle recommends that you use the same mount point options that your NAS vendor used when certifying the device. Refer to your device documentation or contact your vendor for information about recommended mount-point options.

In general, most vendors recommend that you use the NFS mount options listed in the following table.

Option	Requirement	Description
`hard`	Mandatory	Generate a hard mount of the NFS file system. If the connection to the server fails or is temporarily lost, connection attempts are made until the NAS device responds.
`bg`	Optional	Try to connect in the background if connection fails.
`proto=tcp`	Optional	Use the TCP protocol rather than UDP. TCP is more reliable than UDP.
`vers=3`	Optional	Use NFS version 3. Oracle recommends that you use NFS version 3 where available, unless the performance of version 2 is later.
`suid`	Optional	Allow clients to run executables with SUID enabled. This option is required for Oracle software mount points.
`rsize`	Mandatory	The number of bytes used when reading from the NAS device. This value should be set to the maximum database block size supported by this platform. A value of 8192 is often recommended for NFS version 2 and 32768 is often recommended for NFS version 3.
`wsize`	Mandatory	The number of bytes used when writing to the NAS device. This value should be set to the maximum database block size supported by this platform. A value of 8192 is often recommended for NFS version 2 and 32768 is often recommended for NFS version 3.
`nointr` (or `intr`)	Optional	Do not allow (or allow) keyboard interrupts to kill a process that is hung while waiting for a response on a hard-mounted file system. Note: Different vendors have different recommendations about this option. Contact your vendor for advice.
`noac`	Mandatory	Disable attribute caching. This option must be set when the database runs in RAC mode. It is also recommended for database instances that are started from different nodes (host systems) at different times in a GRID-like environment. Note: You must specify this option for NFS file systems where you want to install the software. If you do not use this option, Oracle Universal Installer will not install the software in the directory that you specify.
`forcedirectio`	Optional	Use direct I/O (no buffering) for data transfers. Note: You can use this option for file systems that contain only Oracle database files. Do not use it for a file system that contains Oracle software.

The mandatory mount options comprise the minimum set of mount options that you must use while mounting the NFS volumes. These mount options are essential to protect the integrity of the data and to prevent any database corruption. Failure to use these mount options may result in the generation of file access errors. Refer to your operating system or NAS device documentation for more information about the specific options supported on your platform.