VERITAS Storage Foundation 4.1 Oracle Administrator's Guide

Chapter 6, Using Storage Mapping
Prerelease 8 September 2005, 8:55am Oracle File Mapping (ORAMAP)
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Oracle File Mapping (ORAMAP)
VERITAS has defined and implemented two libraries: libvxoramap_64.so for HPUX PA and
libvxoramap_64.sl for HPUX IA architecture. These two libraries provide a mapping
interface to Oracle9i release 2 or later. libvxoramap_64.so serves as a bridge between
Oracle’s set of storage APIs (known as “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 Foundation for Oracle 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. This information can be used to determine the exact location of an
Oracle data block on a physical device and to help identify hot spots.
Note To use the mapping functionality, you must be using Oracle 9.2.0.3 or later.
Mapping Components
The mapping components in the System Global Area (SGA) and Oracle’s representation of these
components are described in this section. 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