Memory Threshold Notifications
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.
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Contents
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Information About Memory Threshold Notifications
•How to Define Memory Threshold Notifications
•Configuration Examples for Memory Threshold Notifications
•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 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
To set a low free memory threshold, perform the following steps:
SUMMARY STEPS
1. enable
2. configure terminal
3. memory free low-watermark {processor threshold | io threshold}
DETAILED STEPS
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. To reserve a region of memory to be used by the router for the issuing of critical notifications, perform the following steps:
SUMMARY STEPS
1. enable
2. configure terminal
3. memory reserve critical kilobytes
DETAILED STEPS
Configuration Examples for Memory Threshold Notifications
The following examples show how to configure a router to issue notifications when available memory falls below a specified threshold and how to reserve memory for critical notifications:
•Setting a Low Free Memory Threshold: Examples
•Reserving Memory for Critical Notifications: Example
Setting a Low Free Memory Threshold: Examples
The following example specifies a threshold of 20000 KB of free processor memory before the router issues notifications:
Threshold for Free Processor Memory
Router(config)# memory free low-watermark processor 20000
The following example specifies a threshold of 20000 KB of free I/O memory before the router issues notifications:
Threshold for Free IO Memory
Router(config)# memory free low-watermark io 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, another notification message like this is sent:
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 reserves 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
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Logging system messages |
Standards
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No new or modified standards are supported by this feature and support for existing standards has not been modified by this feature. |
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MIBs
RFCs
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No new or modified RFCs are supported by this feature and support for existing RFCs has not been modified by this feature. |
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Technical Assistance
Feature Information for Memory Threshold Notifications
Table 1 lists the release history for this feature.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which 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 software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
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