Veritas Storage Foundation 5.0 for Oracle RAC Configuration Guide Extracts for HP Serviceguard Storage Management Suite, Second Edition, May 2008

Investigating I/O Performance for SG Oracle RAC: Storage Mapping
Oracle File Mapping (ORAMAP)
Chapter 6
128
Oracle File Mapping (ORAMAP)
Veritas has defined and implemented two libraries:
For HP-UX IA: libvxoramap_64.so
For HP-UX PA: libvxoramap_64.sl
These two libraries provide a mapping interface to Oracle 10g release 2 or a later
release. These two libraries serve as a bridge between the Oracle’s set of storage APIs
(ORAMAP) and Veritas Federated Mapping Service (VxMS), a library that assists in the
development of distributed SAN applications that must share information about the
physical location of files and volumes on a disk.
With Veritas Storage Mapping option, you can view the complete I/O topology mapping
of datafiles through intermediate layers like logical volumes down to actual physical
devices. You can use this information to determine the exact location of an Oracle data
block on a physical device and to help identify hot spots.
NOTE Mapping functionality requires Oracle 9.2.0.3 or a later version.
The topics in this section include:
• “Mapping Components” on page 128
• “Storage Mapping Views” on page 129
• “Verifying Oracle File Mapping Setup” on page 129
• “Enabling Oracle File Mapping” on page 130
• “Accessing Dynamic Performance Views” on page 130
• “Using Oracle Enterprise Manager” on page 131
• “About Arrays for Storage Mapping and Statistics” on page 132
Mapping Components
Review the information on the mapping components in the System Global Area (SGA)
and Oracle’s representation of these components. You will need an understanding of
these components to interpret the mapping information in Oracle’s dynamic
performance views.
The mapping information in Oracle’s dynamic performance views consists of:
• File components
A mapping file component is a mapping structure describing a file. It provides a set
of attributes for a file, including the file’s size, number of extents, and type. File
components are exported to the user through V$MAP_FILE.
• File extent components
A mapping file extent component describes a contiguous group of blocks residing on
one element. The description specifies the device offset, the extent size, the file
offset, the extent type (Data or Parity), and the name of the element where the
extent resides.