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Oracle OS watcher (OSWatcher) tips

Oracle Database Tips by Donald Burleson

The new Oracle OS watcher (OSWatcher) reports CPU, RAM and Network stress, and is a new alternative for monitoring Oracle servers.  OS Watcher complements the Ion tool for proactive Oracle monitoring.

Also see my Oracle file watcher tips and OSWatcher Analyzer Tips

Oracle does not run in a vacuum, and it's important to monitor stress on your server, disk, RAM and network.  Oracle provides several tools for monitoring the external environment, including:

For those who do not have a license to access the AWR dba_hist tables (Oracle performance pack), Oracle OS watcher is a free solution for UNIX/Linux RAC shops:

MOSC note 301137.1 has the users guide for Oracle OS Watcher (OSW), a collection of UNIX C shell scripts that help diagnose server and network bottlenecks.  The Oracle OS watcher is nicknamed OSWatcher, and it is user-configurable, collecting one hour worth of OS data at one minute intervals, and then writing the hour's data to an archive flat file...

Actually the sample interval is configurable down to 1 second as opposed to one minute. Default value is 30 seconds.

Oracle OS watcher is especially useful for Linux/UNIX-based RAC systems where monitoring the OS is important for identifying CPU, RAM or network stress.  Oracle OS Watcher may invoke these popular UNIX/Linux utilities, depending on the platform (Solaris, HP/UX, Linux and Tru64):

  • vmstat
  • iostat
  • top
  • netstat
  • traceroute

 Starting Oracle OS Watcher (OSWatcher)

You can start Oracle OS Watcher with this command, specifying the data collection interval (in seconds) and the max number of hours to keep archive files. In this example we submit the collector as a background job to collect every 5 minutes and keep 24 hours of archive files, writing all messages to oswatcher.log:

nohup /u01/app/oracle/scripts/ 300 24 & > /u01/app/oracle/scripts//oswatcher.log

Downloading OSWatcher

You can download Oracle OSWatcher here:

Using Oracle OS Watcher requires knowledge of UNIX and Linux C shell commends syntax, but it removes much of the tedium from OS  monitoring for those who are not licensed to use AWR automatic OS statistics collection.

You can write your own vmstat collection scripts very easily:

# run vmstat and direct the output into the Oracle table . . .
cat /tmp/msg$$|sed 1,3d | awk  '{ printf("%s %s %s %s %s %s\n", $1, $8, $9,
14, $15, $16) }' | while read RUNQUE PAGE_IN PAGE_OUT USER_CPU SYSTEM_CPU

      $ORACLE_HOME/bin/sqlplus -s perfstat/perfstat@testsys1<<EOF
      insert into perfstat.stats\$vmstat
                           values (

The OSWatcher utility captures performance metrics of the database host, very similar to the Cluster Health Monitor. While both tools are similar, they have their differences. The list below highlights some of the variances between the two.


         OSWatcher may not be able to collect metrics when the system is under a very heavy CPU load while CHM will still be able to gather the data.

         CHM gathers data every second or every 5 seconds depending on the version. By default, OSWatcher gathers data every minute. CHM provides more detail but OSWatcher requires less storage space.

         OSWatcher has an analyzer that can create performance graphs covering a much longer timeframe than CHM's GUI tool.

         CHM lets the database administrator see performance metrics for all nodes in the cluster while OSWatcher analyzes one node at a time.

         CHM runs on Windows but OSWatcher does not. For Windows platforms, use CHM only.

         OSWatcher contains data from top, netstat, and traceroute that is missing from CHM.

         Since CHM is a managed cluster resource, it starts automatically when Grid Infrastructure is started. OSWatcher needs to be manually started although one can certainly create a script to be used on server startup.



The CHM utility is preferred if one must be chosen over the other, primarily due to the first bullet point above. That being said, Oracle does recommend running both tools, if possible, to take advantage of their individual strengths.


The OSWatcher does not gather OS performance metrics on its own. Instead, it relies on the Unix or Linux utilities top, ps, mpstat, ifconfig, vmstat, netstat, iostat, and  traceroute. On Linux, the utilities meminfo and slabinfo will also be used. When OSWatcher starts, it spawns data collector processes. One data collector process will run the vmstat utility, gather the output, store the results in a file, and then go to sleep until collection is needed again. Similar data collector processes work for the other OS utilities.



Unlike CHM, OSWatch is not integrated with any Oracle software, and you must download the utility and install it. The download link can be found in My Oracle Support Note 301137.1 for those that have a paid My Oracle Support Community (MOSC) contract. The download consists of a single tar file. OSWatcher was originally called OSWatcher Black Box. As such, references to the acronym oswbb will be found when working with this tool. Even the download file's name is of the form oswbbxxx.tar where xxx is a version number. Extracting the file's contents produces a directory named oswbb containing the OSWatcher utility.


[oracle@host01 ~]$ tar xvf oswbb730.tar


One of the benefits of OSWatcher is that it will also examine the Cluster Interconnect for the Oracle RAC Cluster. Looking at the private network is not set up by default. Before OSWatcher is started for the first time, the database administrator needs to create a file named in the OSWatcher directory with the platform appropriate traceroute command. OSWatcher includes a file named that shows sample commands for each supported platform. The following shows the file for a 2-node Linux cluster. This file exists on host01 and the traceroute command is to host02. The last line below changes the file's permissions to allow the file to be executable.


[oracle@host01 oswbb]$ cat

echo "zzz ***"`date`

traceroute -r -F host02-priv

[oracle@host01 oswbb]$ chmod 755


If there were three nodes in the cluster, the file on host01 would contain a second traceroute command to host03-priv. Similarly, OSWatcher configuration on the other nodes in the cluster would contain traceroute commands to the other nodes in the cluster.


With OSWatcher configured for Oracle RAC, it is time to start the utility so that data can be collected. The script is used to start data collection.



[oracle@host01 oswbb]$ ./ 


Info...You did not enter a value for snapshotInterval.

Info...Using default value = 30

Info...You did not enter a value for archiveInterval.

Info...Using default value = 48

Setting the archive log directory to/home/oracle/oswbb/archive


Testing for discovery of OS Utilities...

VMSTAT found on your system.

IOSTAT found on your system.

MPSTAT found on your system.

IFCONFIG found on your system.

NETSTAT found on your system.

TOP found on your system.

Warning... /proc/slabinfo not found on your system.


Testing for discovery of OS CPU COUNT

oswbb is looking for the CPU COUNT on your system

CPU COUNT will be used by oswbba to automatically look for cpu problems


CPU COUNT found on your system.



Discovery completed.


Starting OSWatcher Black Box v7.3.0  on Sat Sep 6 03:58:51 CDT 2015

With SnapshotInterval = 30

With ArchiveInterval = 48


OSWatcher Black Box - Written by Carl Davis, Center of Expertise,

Oracle Corporation

For questions on install/usage please go to MOS (Note:301137.1)

If you need further assistance or have comments or enhancement

requests you can email me


Data is stored in directory: /home/oracle/oswbb/archive


Starting Data Collection...


oswbb heartbeat:Sat Sep 6 03:58:56 CDT 2015



In the example above, OSWatcher was started with default values. Metrics will be obtained every 30 seconds and OSWatcher will retain 48 hours worth of data. When starting OSWatcher as done above, the utility maintains control of the session. Should the session terminate, so will data collection. Also, the screen will be filled with heartbeat information.



oswbb heartbeat:Sat Sep 6 03:59:56 CDT 2015

oswbb heartbeat:Sat Sep 6 04:00:26 CDT 2015

oswbb heartbeat:Sat Sep 6 04:00:56 CDT 2015



To remedy this situation, OSWatcher can be stopped. In another session, the stop script is executed as follows.


[oracle@host01 oswbb]$ ./


Next, OSWatcher will be started in the background:


[oracle@host01 oswbb]$ nohup ./ &


When OSWatcher is started for the first time, the archive directory is created. By default, this directory is a subdirectory of the main oswbb directory. The output below shows the contents of the archive directory.



[oracle@host01 oswbb]$ cd /home/oracle/oswbb/archive


[oracle@host01 archive]$ ls -l


total 40

drwxr-xr-x 2 oracle oinstall 4096 Sep  6 04:00 oswifconfig

drwxr-xr-x 2 oracle oinstall 4096 Sep  6 04:00 oswiostat

drwxr-xr-x 2 oracle oinstall 4096 Sep  6 04:00 oswmeminfo

drwxr-xr-x 2 oracle oinstall 4096 Sep  6 04:00 oswmpstat

drwxr-xr-x 2 oracle oinstall 4096 Sep  6 04:00 oswnetstat

drwxr-xr-x 2 oracle oinstall 4096 Sep  6 03:58 oswprvtnet

drwxr-xr-x 2 oracle oinstall 4096 Sep  6 04:00 oswps

drwxr-xr-x 2 oracle oinstall 4096 Sep  6 03:58 oswslabinfo

drwxr-xr-x 2 oracle oinstall 4096 Sep  6 04:00 oswtop

drwxr-xr-x 2 oracle oinstall 4096 Sep  6 04:00 oswvmstat


The archive directory contains one subdirectory for each process being captured. It should be easy to tell what each subdirectory contains simply by inspecting the directory name. Looking inside one of the directories, we can see the files that contain the metric data.



[oracle@host01 archive]$ cd oswtop


[oracle@host01 oswtop]$ ls -l


total 108

-rw-r--r-- 1 oracle oinstall 14307 Sep  6 03:59 host01.localdomain_top_14.09.06.0300.dat

-rw-r--r-- 1 oracle oinstall 86398 Sep  6 04:32 host01.localdomain_top_14.09.06.0400.dat


OSWatcher will create a new data file each hour. Each file contains a line with the string "zzz ***" followed by a timestamp. The lines that follow the timestamp are the output of the OS command. As an example, the following output shows the contents of the private network traceroute commands.



[oracle@host01 oswprvtnet]$ cat host01.localdomain_prvtnet_14.09.06.0300.dat


zzz ***Sat Sep 6 03:58:56 CDT 2015

traceroute to host02-priv (, 30 hops max, 60 byte packets

 1  host02-priv.localdomain (  0.292 ms  0.166 ms  0.268 ms


[oracle@host01 oswprvtnet]$ cat host01.localdomain_prvtnet_14.09.06.0400.dat


zzz ***Sat Sep 6 04:27:41 CDT 2015

traceroute to host02-priv (, 30 hops max, 60 byte packets

 1  host02-priv.localdomain (  0.363 ms  0.182 ms  0.108 ms


OSWatcher includes a File Manager process that will run once per hour to clean up any data files older than the retention period. The collection interval and retention period can be changed with the first two parameters, respectively, to the shell script that starts OSWatcher. The following starts OSWatcher to collect metrics every 120 seconds and store the data for 72 hours.


[oracle@host01 oswbb]$ ./OSWatcher 120 72


This section has provided the information for the database administrator to get the OSWatcher utility up and running. While very similar to the Cluster Health Monitor, the OSWatcher has enough differences to warrant using both tools. Just as CHM has a utility to help analyze the data, OSWatcher has its utility that is discussed in the next section.

Learn RAC Tuning Internals!

This is an excerpt from the landmark book Oracle RAC Performance tuning, a book that provides real world advice for resolving the most difficult RAC performance and tuning issues.

Buy it  for 30% off directly from the publisher.



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