4 Configuring Oracle Real Application Clusters Storage

4.1.1 Disabling Write Caching

You must disable write caching on all disks that will be used to share data between the nodes in your cluster. Perform these steps to disable write caching:

1. Click Start, then click Settings, then Control Panel, then Administrative Tools, then Computer Management, then Device Manager, and then Disk drives.

2. Expand the Disk drives and double-click the first drive listed.

3. Under the Disk Properties tab for the selected drive, uncheck the option that enables the write cache.

   For Windows 2000, select the option Optimize for quick removal on the Policies tab.

4. Double-click each of the other drives that will be used by Oracle Clusterware and Oracle RAC and disable write caching as described in the previous step.

4.1.2 Enabling Automounting for Windows 2003

If you are using Windows 2003, then you must enable disk automounting, depending on the Oracle products that you are installing and on other conditions. You must enable automounting when using:

• Raw, or unformatted, partitions for Oracle Real Application Clusters (Oracle RAC)

• Cluster file system for Oracle RAC

• Oracle Clusterware

• Unformatted partitions for single-node database installations

• Logical drives for Automatic Storage Management (ASM)

To enable automounting:

1. Enter the following commands at a command prompt:

   c:\> diskpart
   DISKPART> automount enable
   Automatic mounting of new volumes enabled.
   

2. Type exit to end the diskpart session

3. Repeat steps 1 and 2 for each node in the cluster.

4. When you have prepared all of the cluster nodes in your Windows 2003 system as described in the previous steps, restart all of the nodes.

4.2.1 Overview of Oracle Database and Recovery File Storage Options

There are four ways to store Oracle Database and recovery files on shared disks:

• ASM (database files only): ASM is an integrated, high-performance database file system and disk manager for Oracle files. Because ASM requires an Oracle Database instance, it cannot contain Oracle software, but you can use ASM to manage database and recovery files. If you are using Oracle Standard Edition and Real Application Clusters (Oracle RAC), then you must use ASM to store all the database files.

• Oracle Cluster File System (OCFS): Note that if you intend to use OCFS for your database files, then you should create partitions large enough for the all the database and recovery files when you create partitions for use by Oracle Database.

  Note:

  If you want to have a shared Oracle home directory for all nodes, then you must use OCFS.

• Direct Network File Systems (NFS): You can configure Oracle Database to access NFS V3 servers directly using an Oracle internal Direct NFS client.

• Raw storage: If you choose to use raw storage instead of ASM or OCFS for storing data files, then you must manually manage the disk space with Microsoft Windows disk management tools or by tools provided by third party vendors. Also, you must create individual raw volumes or partitions for every shared database file that uses raw storage.

The storage option that you choose for recovery files can be the same as or different from the option that you choose for the database files. However, you cannot use raw storage to store recovery files.

4.2.2 General Storage Considerations

For all installations, you must choose the storage options that you want to use for Oracle Clusterware files and Oracle Database files. If you want to enable automated backups during the installation, then you must also choose the storage option that you want to use for recovery files (the flash recovery area). You do not have to use the same storage option for each file type.

For single-instance Oracle Database installations using Oracle Clusterware for failover, you must use OCFS, ASM, or shared raw disks if you do not want the failover processing to include dismounting and remounting the disks containing your database files.

The following table shows the storage options supported for storing Oracle Clusterware files, Oracle Database files, and Oracle Database recovery files. Oracle Clusterware files include the Oracle Cluster Registry (OCR) and the voting disk. Oracle Database files include data files, control files, redo log files, the server parameter file, and the password file.

https://metalink.oracle.com

Use the following guidelines when choosing the storage options that you want to use for each file type:

• If you meet all of the requirements listed for the chosen storage options, then you can choose any combination of the supported storage options for each file type.

• Oracle recommends that you choose ASM as the storage option for database and recovery files.

• For Standard Edition cluster installations, ASM is the only supported storage option for database or recovery files.

• If you intend to use ASM with Oracle RAC, and you are configuring a new ASM instance, then you must ensure that your system meets the following conditions:

  • All nodes on the cluster have Oracle Clusterware release 1 (11.1) installed

  • Any existing ASM instance on any node in the cluster is shut down

• If you intend to upgrade an existing Oracle RAC database, or an Oracle RAC database with ASM instances, then you must ensure that your system meets the following conditions:

  • The Oracle RAC database or Oracle RAC database with ASM instance is running on the node from which the Oracle Universal Installer (OUI) and Database Configuration Assistant (DBCA) is run

  • The Oracle RAC database or Oracle RAC database with ASM instance is running on the same nodes that you intend to make members of the new cluster installation. For example, if you have an existing Oracle RAC database running on a three node cluster, then you must install the upgrade on all three nodes. You cannot attempt to upgrade only 2 nodes of the cluster.

4.2.3 Guidelines for Placing Oracle Data Files on a File System

If you decide to place the Oracle data files on OCFS, then use the following guidelines when deciding where to place them:

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

  • If you want to use a single cluster file system, then choose a cluster 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 methodology, also known as SAME.

  • If you want to use more than one cluster file system, then choose cluster file systems on separate physical devices or partitions 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 Oracle Optimal Flexible Architecture (OFA) guidelines. To implement this method, you must choose either the Advanced database creation option or choose the Custom installation type during installation.

• If you intend to create a preconfigured database during the installation, then the cluster file system (or systems) that you choose must have at least 4 GB of free disk space.

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

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

  Note:

  You must not create an NTFS partition on a disk that you are using for OCFS.

• The default location suggested by Oracle Universal Installer for the database file directory is a subdirectory of the Oracle base directory. However, this default location is not appropriate for Oracle RAC production databases.

4.2.4 Guidelines for Placing Oracle Recovery Files on a File System

You must choose a location for recovery files prior to installation only if you intend to enable automated backups during installation.

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

• To prevent disk failure from making the database files as well as the recovery files unavailable, place the recovery files on a cluster file system that is on a different physical disk from the database files.

  Note:

  Alternatively use an ASM disk group with a normal or high redundancy level for either or both file types, or use external redundancy.

• The cluster file system that you choose should have at least 3 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 to specify a different value.

  See Also:

  Oracle Database Backup and Recovery Basics for more information about sizing the flash recovery area.

• The default location suggested by Oracle Universal Installer for the recovery area directory is a subdirectory of the Oracle base directory. However, this default location is not appropriate for Oracle RAC production databases.

4.2.5 After You Have Selected Disk Storage Options

When you have determined your disk storage options, you must perform the following tasks in the following order:

1: Check for available storage with CVU

Refer to "Checking for Available Shared Storage with CVU" .

2: Configure storage for Oracle Database files and recovery files

• To use a OCFS for database or recovery file storage, refer to "Configuring Storage for Oracle Database Files on a Shared File System" to create volumes or partitions with sizes sufficient to store Oracle Database files and binaries.

• To use ASM for database or recovery file storage, refer to "Configuring Disks for Automatic Storage Management".

• To use raw devices (partitions) for database file storage, refer to "Configuring Logical Volumes or Unformatted Partitions".

• To use a network file system (NFS) for database file or recovery file storage, refer to "Configuring Direct NFS Storage for Data Files".

4.4.1 General Steps for Configuring Automatic Storage Management

Follow these steps to configure ASM:

1. Identify your site's storage requirements.

2. Optionally, use an existing ASM disk group.

3. If you are creating a new ASM disk group, then create partitions for DAS or SAN disks.

4. Use one of the following methods to complete the ASM configuration:

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

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

4.4.2 Step 1: Identifying Storage Requirements for Automatic Storage Management

To identify the storage requirements for using ASM, 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 ASM for Oracle data files, recovery files, or both.

   Note:

   You do not have to use the same storage mechanism for data files and recovery files. One can use the file system, while the other uses ASM. If you plan to use ASM for both data files and recovery files, then you should create separate ASM disk groups for the data files and the recovery files.

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

   • If you select an installation method that runs DBCA in interactive mode (for example, by choosing the Advanced database configuration option), then you can decide whether you want to use the same ASM disk group for data files and recovery files. You can also choose to use different disk groups for each file type. Ideally, you should create separate ASM disk groups for data files and recovery files.

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

   • If you select an installation type that runs DBCA in non-interactive mode, then you must use the same ASM disk group for data files and recovery files.

2. Choose the ASM redundancy level that you want to use for the ASM disk group.

   The redundancy level that you choose for the ASM disk group determines how ASM mirrors files in the disk group, and determines the number of disks and amount of disk space that you require. The redundancy levels are 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 ASM 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, ASM uses two-way mirroring by default (except for the control file, which is mirrored three ways), 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 use normal redundancy disk groups.

   • High redundancy

     In a high redundancy disk group, ASM 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 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 data 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 already exists 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 next set of procedures describes how to identify existing disk groups and determine the free disk space that they contain.

4. Optionally identify failure groups for the ASM disk group devices.

   Note:

   You need to complete this step only to use an installation method that runs DBCA in interactive mode. Do this if, for example, you 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. Failure groups define ASM disks that share a common potential failure mechanism. For more information about ASM failure groups, refer to Oracle Database Storage Administrator's Guide.

   Note:

   If you define custom failure groups, 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 ASM disk group should be the same size and have the same performance characteristics.

   • Do not specify two or more partitions on a single physical disk as ASM disks in the same disk group. ASM expects each device for a disk group to be on a separate physical disk.

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

   Tip:

   As you progress through the following steps, make a list of the raw device names you intend to use and have it available during your database or ASM installation.

4.4.3 Step 2 (Optional): Using an Existing Automatic Storage Management Disk Group

To use ASM as the storage option for either database or recovery files, and an existing ASM disk group already exists, you have the following options, depending on the installation method that you select:

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

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

• If you select an installation type that runs DBCA in non-interactive mode, then you must choose an existing disk group for the new database; you cannot create a new disk group. However, you can add disk devices to an existing disk group if the existing disk group has insufficient free space for your requirements.

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

1. In the Services Control Panel, make sure that the OracleASMService+ASMn service, where n is the node number, has started.

2. Open a Windows command prompt and temporarily set the ORACLE_SID environment variable to specify the appropriate value for the ASM instance that you want to use.

   For example, if the ASM SID is named +ASM1, then enter a setting similar to the following:

   C:\> set ORACLE_SID = +ASM1
   

3. Use SQL*Plus to connect to the ASM instance as the SYS user with the SYSASM privilege and start the instance if necessary with a command similar to the following:

   C:\> sqlplus /nolog
   SQL> CONNECT SYS AS SYSASM
   Enter password: sys_password
   Connected to an idle instance.
   
   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 disk group:

   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.

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

To use direct-attached storage (DAS) or storage area network (SAN) disks for ASM, each disk must have a partition table. Oracle recommends creating exactly one partition for each disk that encompasses the entire disk.

Use Microsoft Computer Management utility or the command line tool diskpart to create the partitions. Ensure that you create the partitions without drive letters. After you have created the partitions, the disks can be configured.

4.4.5 Step 4: Manually Configuring Disks for Automatic Storage Management

To use ASM with DAS or SAN devices, the disks must be stamped with a header. If you install Oracle Database in interactive mode, then Oracle Universal Installer configures the disks' headers during the installation process.

However, if you plan to install Oracle Database in noninteractive mode, then you need to configure the disks manually before installation either by using asmtoolg (GUI version) or using asmtool (command line version). You can also use these tools to reconfigure the disks after installation. The asmtoolg and asmtool utilities only work on partitioned disks; you cannot use ASM on unpartitioned disks.

The following section describes the asmtoolg and asmtool functions and commands.

asmtool -add [-force]
\Device\Harddisk1\Partition1 ORCLDISKASM0
\Device\Harddisk2\Partition1 ORCLDISKASM2...

asmtool -addprefix ORCLDISKASM [-force]
\Device\Harddisk1\Partition1
\Device\Harddisk2\Partition1...

asmtool -list [-force]

asmtool -delete ORCLDISKASM0 ORCLDISKASM1...

4.5.1 Creating Partitions for Logical Volumes

You must create the following logical volumes or partitions prior to installing Oracle Database.

To create and configure logical volumes or partitions, use the disk administration tools provided by the operating system or third party vendors. The following administration tools are provided by the operating system:

• Disk Management snap-in to manage disks.

  To access this tool, type diskmgmt.msc at the command prompt. Alternatively, from the Start menu, select Programs, then Administrative Tools, then Computer Management. Then select the Disk Management node in the Storage tree.

• Command line tool to manage disks.

  To access this tool, type diskpart.exe at the command prompt.

http://www.microsoft.com/

You can use the diskpart tool command create partition to create primary or extended partitions, or create logical drives. The following example uses the diskpart tool to create a 120 MB extended partition on disk 100. In this syntax, diskpart.exe is the command line tool for managing disks.

c:\> diskpart.exe
DISKPART> select disk 100
DISKPART> create partition extended size=120

4.5.2 Assigning Logical Names

After creating volumes, assign logical names for Oracle Database. You can assign names to partitions by using importSYMLinks from the command line, or by using Oracle Object Link Manager. To use Oracle Object Link Manager to create persistent symbolic links to the corresponding raw partitions, run the command CRS_home\bin\GUIOracleObjManager.exe

4.5.3 Creating the DBCA Raw Device Mapping File

To enable DBCA to identify the appropriate raw partition symbolic links 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, as in this example:

   C:\>set ORACLE_BASE = E:\oracle
   

2. Create a database subdirectory under the Oracle base directory as in this example:

   C:\>mkdir E:\oracle\dbname
   

   where dbname is the name of the database that you chose previously.

3. Change directory to the %ORACLE_BASE%\dbname directory.

4. Using any text editor, create a file called conf.txt. The file should have the following characteristics:

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

     database_object_identifier = symbolic link name
     

   • For your Oracle RAC database, the file should specify all the shared files for the Oracle RAC database being created. You should have created logical volumes or disk partitions for each of these files, for example:

     • The data files for each tablespace

     • At least one automatic undo tablespace data file

     • The temporary tablespace tempfile

     • At least two redo log files (redon_1, redon_2) for each instance where n is the instance number

     • The system parameter file (SPFILE)

     • The password file

     • At least two control files (control1, control2)

   Note:

   In Windows, by default, \ represents the escape key. To enter a backslash as part of a script, you must enter it in as a string literal. This means that when configuring the mapping file, for Windows to read the mapping file with the path \\.\, you must enter the path as \\\\.\\. Windows reads this as "escape backslash escape backslash period escape backslash."

   The following syntax example is for a mapping file for a two-instance Oracle RAC cluster:

   system=\\\\.\\dbname_SYSTEM 
   sysaux=\\\\.\\dbname_SYSAUX 
   spfile=\\\\.\\dbname_SPFILE 
   users=\\\\.\\dbname_USERS 
   temp=\\\\.\\dbname_TEMP 
   undotbs1=\\\\.\\dbname_UNDOTBS1 
   undotbs2=\\\\.\\dbname_UNDOTBS2 
   control1=\\\\.\\dbname_CONTROL1 
   control2=\\\\.\\dbname_CONTROL2 
   redo1_1=\\\\.\\dbname_REDO1_1 
   redo1_2=\\\\.\\dbname_REDO1_2 
   redo2_1=\\\\.\\dbname_REDO2_1 
   redo2_2=\\\\.\\dbname_REDO2_2 
   example=\\\\.\\dbname_EXAMPLE 
   pwdfile=\\\\.\\dbname_pwdfile
   

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

6. You may optionally set an environment variable, DBCA_RAW_CONFIG, to specify the full path to this file. For the Oracle base defined in Step 1, you would use the following command:

   C:\>set DBCA_RAW_CONFIG=E:\oracle\dbname\conf.txt
   

4.6.1 About Direct NFS Storage

With Oracle Database 11g Release 1 (11.1), you can configure Oracle Database to access NFS V3 servers directly using an Oracle internal Direct NFS client. Some NFS file servers require NFS clients to connect using reserved ports. If your filer is running with reserved port checking, then you must disable it for Direct NFS to operate. To disable reserved port checking, consult your NFS file server documentation.

4.6.2 Using the Oranfstab File with Direct NFS

If you use Direct NFS, then you must create a new configuration file, oranfstab, to specify the options/attributes/parameters that enable Oracle Database to use Direct NFS. You must add the oranfstab file to the ORACLE_BASE\ORACLE_HOME\dbs directory.

For Oracle RAC installations, if you want to use Direct NFS, then you must replicate the oranfstab file on all of the nodes. You must also keep all of the oranfstab files synchronized on all nodes.

When the oranfstab file is placed in ORACLE_BASE\ORACLE_HOME\dbs, the entries in the file are specific to a single database. All nodes running an Oracle RAC database should use the same ORACLE_BASE\ORACLE_HOME\dbs\oranfstab file.

4.6.3 Mounting NFS Storage Devices with Direct NFS

Direct NFS determines mount point settings to NFS storage devices based on the configuration information in oranfstab. If Oracle Database is unable to open an NFS server using Direct NFS, then an error message is written into the Oracle alert and trace files indicating that Direct NFS could not be established.

The Oracle files on the NFS server that are served by the Direct NFS client can be accessed by way of a third party NFS client. The usual considerations for maintaining integrity of the Oracle files apply in this situation.

The database files accessed through Direct NFS Client should also be mounted using other means, such as CIFS or NFS. This ensures that the kernel input and output interface is able to access these files.

4.6.4 Specifying Network Paths with the Oranfstab File

Direct NFS can use up to four network paths defined in the oranfstab file for an NFS server. The Direct NFS client performs load balancing across all of the specified paths. If a specified path fails, then Direct NFS re-issues input and output commands over any remaining paths.

Use the following views for Direct NFS management:

• V$DNFS_SERVERS: Lists the servers that are accessed using Direct NFS.

• V$DNFS_FILES: Lists the files that are currently open using Direct NFS.

• V$DNFS_CHANNELS: Shows the open network paths, or channels, to servers for which Direct NFS is providing files.

• V$DNFS_STATS: Lists performance statistics for Direct NFS.

4.6.5 Enabling Direct NFS Client

To enable Direct NFS Clients, you must add an oranfstab file to ORACLE_BASE\ORACLE_HOME\dbs. When oranfstab is placed in this directory, the entries in this file are specific to one particular database. The Direct NFS Client searches for the mount point entries as they appear in oranfstab. Direct NFS uses the first matched entry as the mount point. Complete the following procedure to enable Direct NFS:

1. Create an oranfstab file with the following attributes for each NFS server that you want to access using Direct NFS:

   • SERVER: The NFS server name.

   • PATH: Up to four network paths to the NFS server, specified either by IP address, or by name, as displayed using the ifconfig command.

   • EXPORT: The exported path from the NFS server. Use a UNIX-style path syntax.

   • MOUNT: The local mount point for the NFS server. Use a WINDOWS-style path syntax.

   The following is an example of an oranfstab file with two NFS server entries:

   server: MyDataServer1
   path: 132.34.35.12
   path: 132.34.35.13
   export: /vol/oradata1 mount: C:\ORACLE\ORADATA\ORCL
    
   server: MyDataServer2
   path: NfsPath1
   path: NfsPath2
   path: NfsPath3
   path: NfsPath4
   export: /vol/oradata2 mount: C:\ORACLE\ORADATA\ORCL2
   export: /vol/oradata3 mount: C:\ORACLE\ORADATA\ORCL3
   

   Note:

   You can specify two optional parameters in oranfstab file:

   • uid: The UNIX user ID to be used by Direct NFS

   • gid: The UNIX group ID to be used by Direct NFS

   The Direct NFS Client uses the uid or gid value to access all NFS servers listed in oranfstab. Direct NFS ignores a uid or gid value of 0.

   Note:

   The exported path from the NFS server must be accessible for read/write/execute by the user with the uid, gid specified in oranfstab or, if neither uid nor gid is listed, by the user with the uid:65534,gid:65534.

2. Oracle Database uses an ODM library, oranfsodm11.dll, to enable Direct NFS. To replace the standard ODM library, oraodm11.dll, with the ODM NFS library, oranfsodm11.dll, complete the following steps:

   1. Change directory to ORACLE_BASE/ORACLE_HOME/bin.

   2. Shutdown Oracle.

   3. Enter the following commands:

      copy oraodm11.dll oraodm11.dll.stub
      copy /Y oranfsodm11.dll oraodm11.dll 
      

4.6.6 Disabling Direct NFS Client

Use one of the following methods to disable the Direct NFS client:

• Remove the oranfstab file.

• Restore the stub oraodm10.dll file by reversing the process you completed in .

• Remove the specific NFS server or export paths in the oranfstab file.

4.6.7 Checking NFS Buffer Size

Direct NFS requires an NFS server supporting NFS read and write buffers of at least 16384 bytes. Direct NFS issues writes at wtmax granularity to the NFS server. Direct NFS cannot serve an NFS server with a wtmax of less than 16384. Oracle recommends that you use the value 32768.