HP PolyServe Software - Manual (Page 4)

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Advanced I/O Monitoring
Introduction
Oracle Database Administrators routinely include operating-system level
performance monitoring tools such as vmstat(8) and iostat(1) in their tuning
efforts. Combining Oracle-provided monitoring tools with these operating-
system tools is usually sufficient in SMP environments hosting single, or very few,
database instances.
With the advent of Real Application Clusters (RAC) and powerful Intel-based
clustered servers, DBAs need I/O performance monitoring tools that are more
“cluster-aware.” With RAC, it is common to find large numbers of clustered
nodes hosting several different databases, each with several different instances
running on the various nodes—all sharing the Storage Area Network.
The thought of monitoring I/O performance of a many-database, many-instance,
many-node clustered environment is rightfully troublesome. Indeed, equipped
with only Oracle Enterprise Manager, Statspack, and GV$ tables and aided by
node-local I/O stats, today's DBAs are lacking for information. I/O information is
important in real-time, not only in periodic reports. Moreover, reports can be
overwhelming. Consider the fact that an 8-node cluster with six instances
accessing the
PROD database and two instances accessing the DEV database will
require eight separate Statspack reports to monitor fully.
While Statspack reports provide invaluable information, they are not sufficient to
monitor the real-time activity of several instances throughout a cluster. Although
GV$tables and Oracle Enterprise Manager help to round out the performance
monitoring stack from Oracle, there is much information missing in a clustered
environment.