MySQL Server Key Cache Write Percent Monitor Monitor

  • ID:  Microsoft.MySQLServer.ManagedServer.Unix.KeyCacheWritePct.Monitor
  • Description:  MySQL Server Key Cache Write Percent Monitor
  • Target:  Monitored MySQL Server (Linux)
  • Enabled:  On Standard Monitoring

Operational States

Name State Description
Over Threshold Success Over Threshold
Under Warning Threshold Warning Under Warning Threshold
Under Error Threshold Error Under Error Threshold

Overridable Parameters

Parameter Name Default Value Description Override
Interval 300 Interval in seconds
Number of Samples 3 Number of Samples
Warning Threshold 90 Warning Threshold
Error Threshold 80 Error Threshold

Alert Details

Monitor State Message Priority Severity Auto Resolution
Under Warning Threshold (Warning) MySQL Server Key Cache Write Percent Medium Match Monitor Health Yes

Run As Profiles

Name
Default

Monitor Knowledgebase

Summary

The percent of physical writes of a key block to disk versus requests to write a key block to the key cache. The MyISAM Key cache is a data structure that contains the most-used index blocks. The key cache size is controlled using the global variable ‘key_buffer_size’. The monitor threshold is analyzed against an average of values returned in polls to the agent where the Number of Samples parameter controls the number of samples included in the calculation of the average.

Causes

An unhealthy state indicates the percentage of writes to the key cache compared to the writes to disk is low. The key cache might not have enough space to store all key blocks. The key cache is updated with a least recently used algorithm.

Resolutions

To address low percent of key cache hits increase key_buffer_size in the configuration file. This can be done by adding the following line along with size under the instance group options: “key_buffer_size= size”. Alternatively the server can be started with the following option: “--key_buffer_size=size”

External References
This monitor does not contain any external references.

See Also for Open Source Software Preview Management Pack


Downloads for Open Source Software Preview Management Pack

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