HP PolyServe Software - Manual (Page 7)

Advanced I/O Monitoring 4
allows DBAs to get a top-level view of the impact PQO is having on the
cluster, either as a whole or at the node level.
• Log Writer. This query focuses on only the lgwr processes and their activity at
the cluster level, database level, or node level. Because all of the Core
Reporting Elements can be returned in this query, it is very beneficial for DBAs
to maintain streaming output of this query showing lgwr activity at either the
cluster level or broken down by database, instance, or node.
• Database Writer. This query is also very helpful. It too can return all Core
Reporting Elements at all Reporting Levels. The special value it adds is to limit
reporting to only dbwr process activity. DBAs can glance at mxodmstat(8)
output and easily determine the average dbwr I/O service times for all
databases cluster-wide, or focus on specific databases, nodes, or instances.
MxODM I/O Monitoring: Configuration
To configure MxODM for Advanced I/O Statistics, you will need to set the
MxODM environment variables.
The MxODM I/O Monitoring feature relies on the proper configuration of the
$MXODM_DBNAME
1
environment variable. To provide accurate database-level
statistics, this variable needs to be set in the environment of all processes
accessing the database, including SQL*Plus processes prior to starting a database
instance and processes that connect through Net Services listener processes.
If the $MXODM_DBNAME environment variable is not set, MxODM presumes
that the database name is a component of the ORACLE_SID environment variable.
For example, if the values of ORACLE_SID in the matrix are “ PROD1 ” and PROD2 ”
and MXODM_DBNAME is NULL clusterwide, summary I/O statistics for both
instances will be reportable via the default database name “ PROD .” If Instance
names in the matrix do not follow the typical convention of DBNAME n, where n is
the logical node number in the cluster, this default scheme will not be correct for
database-wide I/O monitoring. In this case, the $
MXODM_DBNAME variable must
be set.
1. MxODM I/O statistics are collected regardless of environment variable settings. It is crucial,
however, that these variables be set for proper attribution of statistics to the various reporting
categories (node-level, instance-level, database-level, and so on).