Memory Threshold Notifications
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Defining Memory Threshold Notifications

Table Of Contents

Defining Memory Threshold Notifications

Finding Feature Information

Contents

Information About Memory Threshold Notifications

Memory Threshold Notifications

Memory Reservation

How to Define Memory Threshold Notifications

Setting a Low Free Memory Threshold

Reserving Memory for Critical Notifications

Configuration Examples for Memory Threshold Notifications

Setting a Low Free Memory Threshold: Examples

Reserving Memory for Critical Notifications: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for Memory Threshold Notifications


Defining Memory Threshold Notifications


First Published: August 21, 2003
Last Updated: February 28, 2009

The Memory Threshold Notifications feature allows you to reserve memory for critical notifications and to configure a router to issue notifications when available memory falls below a specified threshold.

Finding Feature Information

For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Memory Threshold Notifications" section.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Contents

Information About Memory Threshold Notifications

How to Define Memory Threshold Notifications

Configuration Examples for Memory Threshold Notifications

Additional References

Feature Information for Memory Threshold Notifications

Information About Memory Threshold Notifications

The Memory Threshold Notifications feature provides two ways to mitigate low-memory conditions on a router: notifications can be sent to indicate that free memory has fallen below a configured threshold, and memory can be reserved to ensure that sufficient memory is available to issue critical notifications. To implement the Memory Threshold Notifications feature, you should understand the following concepts:

Memory Threshold Notifications

Memory Reservation

Memory Threshold Notifications

Notifications are messages issued by the router. When you specify a memory threshold using the memory free low-watermark command, for example, the router issues a notification when available free memory falls below the specified threshold, and again once available free memory rises to 5 percent above the specified threshold. The following are examples of memory threshold notifications:

Available Free Memory Less Than the Specified Threshold

000029: *Aug 12 22:31:19.559: %SYS-4-FREEMEMLOW: Free Memory has dropped below 2000k
Pool: Processor  Free: 66814056  freemem_lwm: 204800000

Available Free Memory Recovered to More Than the Specified Threshold

000032: *Aug 12 22:33:29.411: %SYS-5-FREEMEMRECOVER: Free Memory has recovered 2000k
Pool: Processor  Free: 66813960  freemem_lwm: 0

Memory Reservation

Memory reservation for critical operations ensures that management processes, such as event logging, continue to function even when router memory is exhausted.

How to Define Memory Threshold Notifications

This section contains the following procedures:

Setting a Low Free Memory Threshold

Reserving Memory for Critical Notifications

Setting a Low Free Memory Threshold

Perform this task to set a low free memory threshold.

SUMMARY STEPS

1. enable

2. configure terminal

3. memory free low-watermark [processor threshold]

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

memory free low-watermark [processor threshold]

Example:

Router(config)# memory free low-watermark processor 20000

Specifies a threshold in kilobytes of free processor memory. To view acceptable values for the memory threshold, enter the following command:

memory free low-watermark processor ?

Reserving Memory for Critical Notifications

When a router is overloaded by processes, the amount of available memory might fall to levels insufficient for it to issue critical notifications. Perform this task to reserve a region of memory to be used by the router for the issuing of critical notifications.

SUMMARY STEPS

1. enable

2. configure terminal

3. memory reserve critical kilobytes

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

memory reserve critical kilobytes

Example:

Router(config)# memory reserve critical 1000

Reserves the specified amount of memory in kilobytes so that the router can issue critical notifications.

The amount of memory reserved for critical notifications cannot exceed 25 percent of total available memory.

Configuration Examples for Memory Threshold Notifications

This section provides the following configuration examples:

Setting a Low Free Memory Threshold: Examples

Reserving Memory for Critical Notifications: Example

Setting a Low Free Memory Threshold: Examples

Threshold for Free Processor Memory

The following example shows how to specify a threshold of 20000 KB of free processor memory before the router issues notifications:

Router(config)# memory free low-watermark processor 20000

If available free memory falls below the specified threshold, the router sends a notification message like this one:

000029: *Aug 12 22:31:19.559: %SYS-4-FREEMEMLOW: Free Memory has dropped below 20000k
Pool: Processor  Free: 66814056  freemem_lwm: 204800000

Once available free memory rises to above 5 percent of the threshold, the router sends a notification message like this one:

000032: *Aug 12 22:33:29.411: %SYS-5-FREEMEMRECOVER: Free Memory has recovered 20000k
Pool: Processor  Free: 66813960  freemem_lwm: 0

Reserving Memory for Critical Notifications: Example

The following example shows how to reserve 1000 KB of memory for critical notifications:

Router# memory reserved critical 1000


Note The amount of memory reserved for critical notifications cannot exceed 25 percent of total available memory.


Additional References

The following sections provide references related to the Memory Threshold Notifications feature.

Related Documents

Related Topic
Document Title

Cisco IOS XE commands

For information about Cisco IOS XE commands, use the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or the Cisco IOS Master Command List, All Releases, at http://www.cisco.com/en/US/docs/ios/mcl/allreleasemcl/all_book.html.


Standards

Standard
Title

No new or modified standards are supported by this feature and support for existing standards has not been modified by this feature.


MIBs

MIB
MIBs Link

No new or modified MIBs are supported by this feature and support for existing MIBs has not been modified by this feature.

To locate and download MIBs for selected platforms, Cisco IOS XE releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs


RFCs

RFC
Title

No new or modified RFCs are supported by this feature and support for existing RFCs has not been modified by this feature.


Technical Assistance

Description
Link

The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport


Feature Information for Memory Threshold Notifications

Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.


Note Table 1 lists only the Cisco IOS XE software release that introduced support for a given feature in a given Cisco IOS XE software release train. Unless noted otherwise, subsequent releases of that Cisco IOS XE software release train also support that feature.


Table 1 Feature Information for Memory Threshold Notifications

Feature Name
Releases
Feature Information

Memory Threshold Notifications

Cisco IOS XE Release 2.1

This feature was introduced on Cisco ASR 1000 Series Aggregation Services Routers.