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Advanced I/O Monitoring 6

MxODM I/O Monitoring: Practical Examples

This section offers several practical examples of the powerful I/O monitoring

capability of the mxodmstat(8) command. The examples use a question and

answer format, where the answer includes an mxodmstat(8) command and its

output.

The system used for these examples was a six-node, dual-processor, Intel-based

cluster with PolyServe Matrix Server 2.1 and Oracle9i Real Application Clusters

version 9.2.0.4. There were two main databases on the cluster:

• BENCH. This database is a stress-testing environment used at PolyServe. It is

OLTP workload that exhibits realworld characteristics. The BENCH database

has four instances executing on nodes 1 through 4.

• DEV. This database contains a small application under development that

simulates capturing stock trading events. For this set of examples, there were

two instances accessing the

DEV database. The DEV1 instance was executing on

node 5 of the cluster and the

DEV2 instance was on node 6.

Having two databases, one with four instances and another with two instances, is

a good case for demonstrating the invaluable information that DBAs can obtain

with the mxodmstat(8) command.

Example 1

Question: What is the cluster-wide read and write count, I/O throughput (Kbytes),

and average I/O response times with 3-second granularity? How about the read-

to-write ratio?

Answer: This information can be monitored with the -a and -p options of

mxodmstat(8). The op argument directs mxodmstat(8) to break out reads and

writes. When the -p option is supplied, the dataset is enhanced to show I/O

percentages. The I/O service times are also displayed in Millisecond units. Figure

1 shows an example.

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Hp PolyServe Software Manuel d'utilisateur Page 9