About Oracle Disk Manager

Article:HOWTO59499  |  Created: 2011-10-12  |  Updated: 2011-10-12  |  Article URL http://www.symantec.com/docs/HOWTO59499
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About Oracle Disk Manager

Veritas Extension for Oracle Disk Manager enhances file management and disk I/O throughput. The features of Oracle Disk Manager are optimized for Oracle 10g or later databases in a Veritas File System environment. Oracle Disk Manager enables you to improve database throughput for I/O intensive workloads with special I/O optimization.

Veritas Extension for Oracle Disk Manager supports Oracle Resilvering. With Oracle Resilvering, the storage layer receives information from the Oracle database as to which regions or blocks of a mirrored datafile to resync after a system crash. Oracle Resilvering avoids overhead from the Volume Manager Dirty Region Logging (DRL), which increases performance.

On AIX, HP-UX, and Solaris:

Oracle Disk Manager reduces administrative overhead by providing enhanced support for Oracle Managed Files. Veritas Extension for Oracle Disk Manager has Quick I/O-like capabilities, but is transparent to the user. Unlike Veritas Quick I/O, files managed using Veritas Extension for Oracle Disk Manager do not require special file naming conventions. The Oracle Disk Manager interface uses regular database files. If you are upgrading to Oracle10g or later, you should convert from Quick I/O to Oracle Disk Manager.

On Linux:

Oracle Disk Manager reduces administrative overhead by providing enhanced support for Oracle Managed Files. Veritas Extension for Oracle Disk Manager is transparent to the user. Files managed using Veritas Extension for Oracle Disk Manager do not require special file naming conventions. The Oracle Disk Manager interface uses regular database files.

Note:

On Linux, Veritas Storage Foundation 4.1 for Oracle was the last major release that supported Oracle Disk Manager for raw devices.

Database administrators can choose the datafile type used with the Oracle product. Historically, choosing between file system files and raw devices was based on manageability and performance. The exception to this is a database intended for use with Oracle Parallel Server, which requires raw devices on most platforms. If performance is not as important as administrative ease, file system files are typically the preferred file type. However, while an application may not have substantial I/O requirements when it is first implemented, I/O requirements may change. If an application becomes dependent upon I/O throughput, converting datafiles from file system to raw devices is often necessary.

Oracle Disk Manager was designed to work with Oracle10g or later to provide both performance and manageability. Oracle Disk Manager provides support for Oracle's file management and I/O calls for database storage on VxFS file systems and on raw volumes or partitions. This feature is provided as a dynamically-loaded shared library with which Oracle binds when it is loaded. The Oracle Disk Manager library works with an Oracle Disk Manager driver that is loaded in the kernel to perform its functions.

The benefits of using Oracle Disk Manager are as follows:

  • True kernel asynchronous I/O for files and raw devices

  • Reduced system call overhead

  • Improved file system layout by preallocating contiguous files on a VxFS file system

  • Performance on file system files that is equivalent to raw devices

  • Transparent to users

For more information on using Oracle Disk Manager:

See Veritas Storage Foundation: Storage and Availability Management for Oracle Databases.


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