Veritas Storage Foundation™ 5.0.1 for Oracle RAC Installation, Configuration, and Administrator's Guide Extracts for the HP Serviceguard Storage Management Suite on HP-UX 11i v3

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” (page 90)
• “Storage Mapping Views” (page 91)
• “Verifying Oracle File Mapping Setup” (page 91)
• “Enabling Oracle File Mapping” (page 91)
• “Accessing Dynamic Performance Views” (page 92)
• “Using Oracle Enterprise Manager” (page 93)
• “About Arrays for Storage Mapping and Statistics” (page 93)
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$MAP_FILE.
• File extent components
A mapping file extent component describes a contiguous group of blocks residing on one
element. The description specifies the device offset, the extent size, the file offset, the extent
type (Data or Parity), and the name of the element where the extent resides.
• Element components
A mapping element component is a mapping structure that describes a storage component
within the I/O stack. Elements can be mirrors, stripes, partitions, RAID5, concatenated
elements, and disks.
This component contains information about the element’s mapping structure, such as the
element’s size, type, number of subelements, and a brief description. Element components
are exported to the user through V$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.
90 Investigating I/O Performance for SGeRAC: Storage Mapping