Donald K. Burleson    Oracle9i RAC Tips

Configure Shared Storage

Ordinarily, the data files, control files, and redo log files need to reside on the unformatted raw devices on a Windows NT or a Windows 2000 platform. However, with the Oracle9i Release 2 (9.2.0.1.0) there is the option of using the cluster file system for setting up the shared storage volumes for the RAC database. If Oracle9i Release 1 (9.0.1.0.0) is being installed, logical partitions (otherwise known as RAW Partitions) for the shared disks must still be used.

In a Windows environment, the raw devices are more commonly known as logical drives that reside within extended partitions. The extended partitions point to raw space on the disk.

Creating Logical Drives (Raw Partitions)

To configure the logical drives, create logical partitions using Windows NT Disk administrator or Windows 2000 Computer Manager.

First, create the extended partitions for the hard disks in the array and then create as many logical partitions as required for the database files. Only one extended partition can be created for each disk. Oracle recommends creating the extended partition on an un-partitioned disk and using the entire disk for the extended partition.

Creating an Extended Partition on Windows 2000

1. Log in as a member of the Local Administrators Group.

2. From Administrative Tools, select Computer Management. In the console tree, select Disk Management.

3. To create extended partitions, right-click the unallocated region of a basic disk, and choose Create Partition.

4. In the Create Partition wizard, choose Next > Extended Partition.

5. Choose Extended Partition. Choose Next.

6. Choose the maximum amount of space and click Next.

7. A summary screen will come up. Choose Finish.

8. Repeat until all Extended Partitions are complete.

Creating a Logical Partition on Windows 2000

1. To create the logical partitions, right-click again on the extended partition and choose Create Logical Drive.

2. Follow the instructions in the wizard, choosing the appropriate size for the desired partition, choosing to not assign any drive letters, and choosing no format.

3. Repeat until all logical drives are complete.

The following table gives the list of the raw partitions expected by the database creation utility.

Oracle Cluster File System (OCFS) for Windows

OCFS is a shared file system specifically designed for Real Application Clusters. It allows multiple nodes to share Oracle Home and databases on a single SAN volume. All nodes in the cluster have concurrent ownership and access to the shared disks. For OCFS on Windows, Oracle supports all database files and installation of the Oracle software. It was designed for use of an Oracle database, not a new general-purpose file system. The single shared Oracle Home provides a consistent image of binaries and metadata across the cluster. Oracle patch upgrades become relatively easy with one set of binaries.

However, according to Oracle Metalink Note # 225550.1, the current version of OCFS does not support access from mapped drives in the Windows environments. In other words, it is not possible to copy a file from a client to a mapped OCFS drive. Nor is it possible to modify an existing file on an OCFS drive. For managing the configuration files in ORACLE_HOME, a couple of alternative approaches are available:

• Access from any of the nodes within the cluster is possible, so any modifications can be made directly from a node.

• Install the Oracle Home on a local NTFS drive rather than an OCFS drive. This will allow mapping to the NTFS drive with full control permissions.

This functionality is planned for a future OCFS release.

Configuration of OCFS drive involves the following steps:

1. Configure the shared SAN volume for Oracle home and data files.

2. Run clustercheck to verify the existence of all nodes in the cluster. It lists node names and confirms IP addresses, and confirms file level and registry accessibility to each node in the cluster.

3. Run Windows 2000 Disk Administrator and create an extended partition on the SAN volume with a minimum size of 100MB. Do not format and do not assign a logical drive letter at this stage.

4. Run the Oracle Cluster Wizard from the CFS product CD: \preinstall_rac\clustersetup\clustersetup.exe. Then format the SAN shared partition in OCFS format and assign the logical drive. This step also installs the following services on all nodes in the cluster:

• OracleObjectService

• OracleCMService9i

• OracleClusterVolumeService

5. Next, run the Oracle Universal Installer to install the OracleCluster File System support software and patches. It discovers the nodes in the cluster automatically and enables installation on the individual nodes. Install OCFS components and patches in Oracle_Home.

For more up-to-date details see, Metalink Note (Note:178882.1) titled ‘Step-By-Step Installation of RAC on Windows 2000 or NT’.

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