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RAW DEVICE vs. OCFS

ericfjchen
Regular Advisor

RAW DEVICE vs. OCFS

Oracle9i Database Release 2 (9.2.0.4.0) for Linux x86. Should we choose raw device or OCFS?
Why?

Thanks

Eric
3 REPLIES
Indira Aramandla
Honored Contributor

Re: RAW DEVICE vs. OCFS

Hi Eric,

When to use CFS over RAW is very dependent on the availability of a CFS on your platform. And when to use RAW over CFS is due to the reason "Raw is sometimes used for performance reasons and is required for most unix platforms and all windows platforms for RAC and OPS.

The latest OCFS version for Linux is available via Metalink Patch section.
Oracle9i patchset 9.2.0.3 includes a fix to place the srvm shared config device on OCFS as well.

CFS is part of Oracle's Linux Projects and can be downloaded from
http://oss.oracle.com/
which has a pointer to the OCFS project. This location is the only source for current OCFS versions. Oracle Metalink is no longer used to store OCFS updates

Attached is a document that describes in brief about the RAW devices and CFS(Cluster File Systems)and when to use what.


I hope this gives you some idea.


Indira A


Never give up, Keep Trying
Indira Aramandla
Honored Contributor

Re: RAW DEVICE vs. OCFS

Eric,

More in Metalink :-

OCFS is currently only supported on Red Hat Advanced Server 2.1 using SMP or Enterprise kernel or UnitedLinux 1.0, and without additional modifications or patches, except for the one provided by Oracle. If you modify the kernel, then Oracle Corporation cannot support it.

Features of OCFS.
Oracle Cluster File System (OCFS) is a shared file system designed specifically for Oracle Real Application Clusters (RAC). OCFS eliminates the requirement for Oracle database files to be linked to logical drives. OCFS volumes can span one shared disk or multiple shared disks for redundancy and performance enhancements.

OCFS is designed to provide an alternative to using raw devices for Oracle 9iRAC. Managing raw devices is usually a difficult task.

A cluster file system allows a number of nodes in a cluster to concurrently access a given file system. Every node sees the same files and data. This allows easy management of data that needs to be shared between nodes.

OCFS on Linux implements most of the features of a generic cluster file system. For Oracle9i Real Application Clusters customers, OCFS will eliminate the need to manage and set up raw devices, making cluster database administration much easier as it looks and feels just like a regular file system. With Raw Devices it is possible to have a maximum of 255 raw partitions, on OCFS there are no limit on number of files.

Moreover, with a shared file system, the different instances of the database can share archive logs, which makes media recovery much more convenient because every node has access to all archived log file when needed. Known Limitations: at this time Oracle Cluster File System supports Oracle Datafiles. This includes Redo Log files, Archive log files, Controlfiles and database Datafiles. The shared quorum disk file for the cluster manager and the shared init file (srv) are also supported.


Indira A
Never give up, Keep Trying
ericfjchen
Regular Advisor

Re: RAW DEVICE vs. OCFS

If we want to use Oracle RMAN to online backup database, which choice will increase the database recovery difficulty?