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

6 Investigating I/O Performance for SGeRAC: Storage
Mapping
This chapter contains the following topics:
• “About Storage Mapping in SGeRAC” (page 85)
• “Understanding Storage Mapping” (page 85)
• “Verifying Veritas Storage Mapping Setup” (page 86)
• “Using vxstorage_stats” (page 86)
• “Displaying I/O Statistics Information” (page 87)
• “Using dbed_analyzer” (page 88)
• “Oracle File Mapping (ORAMAP)” (page 89)
About Storage Mapping in SGeRAC
The storage mapping feature available with SGeRAC enables you to map datafiles to physical
devices. You can obtain and view detailed storage topology information using the
vxstorage_stats and dbed_analyzer commands. You can also use the Oracle Enterprise
Manager to access storage mapping information.
Understanding Storage Mapping
Access to mapping information is important since it allows for a detailed understanding of the
storage hierarchy in which files reside, information that is critical for effectively evaluating I/O
performance.
Mapping files to their underlying device is straightforward when datafiles are created directly
on a raw device. With the introduction of host-based volume managers and sophisticated storage
subsystems that provide RAID features, however, mapping files to physical devices has become
more difficult.
With the SGeRAC Storage Mapping option, you can map datafiles to physical devices. Veritas
Storage Mapping relies on Veritas 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.
The Veritas Storage Mapping option supports Oracle’s set of storage APIs called Oracle Mapping
(“ORAMAP” for short) that lets Oracle determine the mapping information for files and devices.
Oracle provides a set of dynamic performance views (v$ views) that shows the complete
mapping of a file to intermediate layers of logical volumes and physical devices. These views
enable you to locate the exact disk on which any specific block of a file resides. You can use these
mappings, along with device statistics, to evaluate I/O performance.
The Veritas Storage Mapping option supports a wide range of storage devices and allows for
“deep mapping” into EMC, Hitachi, and IBM Enterprise Storage Server (“Shark”) arrays. Deep
mapping information identifies the physical disks that comprise each LUN and the hardware
RAID information for the LUNs.
You can view storage mapping topology information and I/O statistics using the following:
Table 6-1 View Storage and I/O Information Commands
This command displays the complete I/O topology mapping of specific datafiles through
intermediate layers like logical volumes down to actual physical devices.
vxstorage_stats
This command retrieves tablespace-to-physical disk mapping information for all the
datafiles in a specified database. It also provides information about the amount of disk
space being used by a tablespace.
dbed_analyzer
About Storage Mapping in SGeRAC 85