The Memory Usage Monitor uses a local API call or SNMP communication to test the amount of physical memory (RAM) available on:
- The local machine
- A remote SNMP-enabled computer running Microsoft® Windows® NT, 2000, XP or 2003
- A remote SNMP-enabled computer running a Unix-Based Operating System (Linux, Solaris, HP-UX, etc.)
- An SNMP-enabled device
It effectively ensures that:
- Memory leaks are detected before performance can be affected.
- The minimum amount of physical memory required by the system remains available.
- The total amount of physical memory allotted to the server is not exceeded.
The Memory Usage Monitor Wizard is designed to help you configure a Memory Usage Monitor with the least amount of initial input. There are a number of benefits to this approach:
- Configuration is fast and easy, allowing you to get the Monitor up and running quickly.
- The Memory Usage Monitor Wizard allows you to test all the parameters you enter along the way to make sure that the Monitor will work as expected immediately upon being enabled to go live in a production environment.
The following example illustrates the process of creating a new Memory Usage Monitor to monitor memory on a remote computer running Microsoft Windows XP.
To create a new Memory Usage Monitor:
- Log in to the ipMonitor Administration web interface.
- Click the Monitors menu option, and then click Add Monitor.
- Select the Memory Usage Monitor Monitor from the Resource Based category and then click the Continue button.
IP Address / Domain Name
Specify the location of the server or device you want to monitor. Both IP Address and Domain Name are valid entries.
An example of a valid Fully Qualified Domain Name is: www.ipmonitor.com
An example of a valid IP address is: 10.200.50.1
UDP Port
Specify the Port Number that the server or device responds on. By default, the standard Port Number used for SNMP communication (Port 161) is already entered.
Community
SNMP Community strings act like passwords for SNMP information. When ipMonitor issues a SNMP Get command to the SNMP Agent at this IP address, it sends out the SNMP Community string. If the Community string is correct, the SNMP Agent processes the request and returns results for analysis.
SNMP default communities are:
- Private (Read / Write)
- Public (Read Only)
Some SNMP Agents are configured to use non-default Community strings. This is typically done to improve SNMP security, often in conjunction with a non-standard SNMP Port.
SNMP Version
Select the SNMP version used by the device to be monitored. Both ipMonitor and the target device must use the same SNMP Version. Available options are: SNMP Version 1 and SNMP Version 2.
Communication Type
Select the communication process used by ipMonitor to connect to the specified computer or remote device:
Local - The Local communication method allows the Monitor to connect to the ipMonitor host machine directly using an API call in order to test the amount of physical memory available on the system.
SNMP - The Simple Network Management Protocol allows the Monitor to perform a lightweight transaction in order to communicate with SNMP-enabled network devices. Select the Management Information Base (MIB) ipMonitor will use to connect to the specified computer or remote device. Three options are available:
- Host Resources MIB - The Host Resources MIB is loaded by default with the SNMP component.
- Informant - SNMP Informant is a popular extension agent developed by Williams Technology Consulting Services for the Microsoft SNMP Service that exposes performance counter-related data. The Informant method is recommended to administrators who are already using SNMP Informant to monitor other aspects of the remote system.
Note: An SNMP Agent has to be installed and running on the server or device being monitored. If the remote system is running Windows 2000, Windows XP or Windows 2003, you will need to install and configure the SNMP Service manually. More information regarding the SNMP Service can be found on the Microsoft web site.
WMI - The Windows Management Instrumentation communication method is recommended to administrators who wish to monitor memory usage on a Windows operating system. When this method is selected, the Monitor connects to the WMI namespace hosting the WMI class corresponding to the memory pool being monitored.
Note: WMI is preinstalled in Windows Vista, Windows Server 2003, Windows XP, and Windows 2000.
Memory Pool
Select the desired memory pool to monitor from the list provided.
The Memory Usage Monitor utilizes two separate threshold values when analyzing test results.
1. Last-Value Threshold - This is the primary threshold rate, which is compared to the value acquired by the Monitor during the most recently performed test.
- Required Free Memory
The amount of physical memory required on the system, either in megabytes (MB) or as a percentage (%). You may need to adjust the default value of 15.00% based on the type of memory pool being monitored.
2. Short-Term Threshold - This is the secondary threshold rate. It uses the test results accumulated over the period of time set within the Sample Size field to detect a slow memory leak versus a spike in memory usage.
- Required Free Memory
The amount of physical memory required on the system, either in megabytes (MB) or as a percentage (%). You may need to adjust the default value of 30.00% based on the type of memory pool being monitored. - Sample Size
The data obtained from the monitoring tests performed during the length of time specified here will be averaged and compared against the most recent test result. By default, the Sample Size value is set to 915 seconds (15 minutes and 15 seconds).
If the Last-Value Threshold rate is exceeded, the Memory Usage Monitor will re-analyze the data by comparing it against the Short-Term Threshold value specified. During this comparison process, the most recent test results are measured against the data obtained from tests that occurred within the length of time specified in the Sample Size field.
This dual threshold method prevents false Alerts from occurring each time a spike in memory consumption is detected. Alerts will only be triggered if memory usage does not return to normal within the required period of time, indicating a memory shortage or a memory leak that may affect system performance.
Monitor Name
Enter a concise, descriptive name for the new Monitor. The Monitor Name will be displayed in the Monitors List, Monitor Status, Reports and Logs pages. Names may not be greater than 64 characters. Since ipMonitor does not use the name field to identify the Monitor internally, Monitor Names can be changed at any time without data loss.
Selected Group
From the drop-down list, select one of the existing Groups to which the new Monitor will automatically be added upon creation.
Create Monitor Enabled
Once the Monitor is created, it will immediately start testing the bandwidth usage on the specified server or device. This option is enabled by default.
Store Monitor Statistics for Recent Activity and Historical Reports
ipMonitor will immediately begin to record test results, which are then used to generate Recent Activity and Historical Reports. This option is disabled by default.
Create
Click the Create button to exit the wizard and access the new Monitor in edit mode. You can make any final modifications to the Monitor in this mode, including setting Timing and Notification parameters.
Once you're satisfied with the configuration settings, click the OK button at the bottom of the page. The new Monitor will be displayed within the Monitors List, and can be accessed for further configuration adjustments at any time.
When the Monitor is in an Up state, test results are reported as shown in the example below:
rtt - Round-Trip Time. This value indicates the time it took the test packet to reach the monitored resource and return a response to ipMonitor. Round-trip time is measured in milliseconds (ms).
avail - These values indicate the amount of physical memory currently available on the system, in megabytes (MB), and as a percentage (%).
avail-avg - This value indicates the average amount of physical memory on the system, based on the tests performed during the length of time specified in the Sample Size field.
When the Monitor is in a Warn, Down, or Lost state, the Last Result field indicates the problem encountered. Different Monitor types generate specific Error Codes in accordance with the technical capabilities of the Monitor. Refer to the Error Codes section of this document for details.
Note1: The Memory Usage Monitor Wizard allows you to configure Memory Usage Monitors quickly and easily. However, if you'd prefer greater control over the process, you can Clone an existing Memory Usage Monitor and make any required configuration changes manually.
Note2: For information on settings common to all Monitor types, such as Identification, Timing, Notification Control and Recovery Parameters, refer to General Monitor Settings.
The following error codes are generated by the Memory Usage Monitor. Error codes are displayed in Real-time and Historical Reports. They can also be added to Alerts using Tokens.
| Message | Details |
|---|---|
| Configuration information for this item is missing some required fields | A required element(s) for Monitor connectivity or testing was not supplied to ipMonitor. |
| The pattern describing the PASS state was not detected | The data sent by the server did not contain the search pattern required for a PASS condition. |
| The specified resource was not found on the remote device | The specified memory pool to be monitored was not found on the remote server or device being queried. |
| Unable to connect to the remote device | The specified address to the connection-based Service is unavailable. |
| Could not obtain an IP address for the remote device | The supplied address was not a valid IP address OR the Server Domain Name could not be translated into an IP address. The Server Domain Name may refer to a local machine name, or to a fully qualified domain name. |
| The remote device sent more data than expected | The server sent more data than expected for this protocol. This is usually due to an error in the software being monitored. |
| The remote device timed out before sending a response | The resource being monitored did not respond within the maximum allowable time. |
| The response from the remote device does not adhere to protocol specification | The resource is either not adhering to the protocol standard or ipMonitor does not understand a proprietary change in the protocol. |
| The remote device failed to respond | The server did not provide any response before disconnecting. |
| The remote device provided an empty list of values | No data was returned from the remote server. |
| The response from the remote device was incomprehensible | The resource being monitored responded with invalid data. |
For information on other features and concepts related to those discussed in this article, refer to the following ipMonitor resources:
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Last Updated: March 30, 2007 | What did you think of this topic?