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
129
• Element components
A mapping element component is a mapping structure that describes a storage
component within the I/O stack. Elements can be mirrors, stripes, partitions, RAID5,
concatenated elements, and disks.
This component contains information about the element’s mapping structure, such
as the element’s size, type, number of subelements, and a brief description. Element
components are exported to the user through V$MAP_ELEMENT.
• Subelement components
A mapping subelement component describes the link between an element and the
next element in the I/O stack. The subelement component contains the subelement
number, size, the element name for the subelement, and the element offset.
Subelement components are exported to the user through V$MAP_SUBELEMENT.
These four types of mapping components completely describe the mapping information
for an Oracle instance.
Storage Mapping Views
The mapping information that is captured is presented in Oracle’s dynamic performance
views. Table 6-4 provides brief descriptions of these views. For more detailed
information, refer to your Oracle documentation.
Verifying Oracle File Mapping Setup
To verify that $ORACLE_HOME is set up for Oracle file mapping (ORAMAP)
Table 6-4 Storage Mapping Views
View Description
V$MAP_LIBRARY Contains a list of all the mapping libraries that have been
dynamically loaded by the external process.
V$MAP_FILE Contains a list of all the file mapping structures in the shared
memory of the instance.
V$MAP_FILE_EXTENT Contains a list of all the file extent mapping structures in the
shared memory of the instance.
V$MAP_ELEMENT Contains a list of all the element mapping structures in the SGA
of the instance.
V$MAP_EXT_ELEMENT Contains supplementary information for all element mapping
structures.
V$MAP_SUBELEMENT Contains a list of all subelement mapping structures in the
shared memory of the instance.
V$MAP_COMP_LIST Describes the component list associated with the element name.
V$MAP_FILE_IO_STACK Contains the hierarchical arrangement of storage containers for
the file. This information is displayed as a series of rows. Each
row represents a level in the hierarchy.