Use this Knowledge Script to monitor the cache hit rate for the LSASS (Windows Local Security Authority Server) process. The cache hit rate is the percentage of time that a requested name is found in the Active Directory cache. This script raises an event if the cache hit rate falls below the threshold you set, which may indicate that you need to re-organize the Active Directory.
LSASS is the process responsible for core Active Directory functions performed using LDAP (Lightweight Directory Access Protocol). Ideally, all LDAP requests can be fulfilled out of RAM. However, when the cache hit rate falls below 95%, Active Directory performance falls off quickly. By 93%, Active Directory is typically unusable.
HINT:If the cache hit rate is low, consider adding physical RAM to the computer, or adding the /3GB switch to the boot.ini file.
This script gathers the following Windows performance counter values for use in data collection and threshold monitoring:
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Performance Objects |
Counter |
|---|---|
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NTDS DirectoryServces |
DS Name Cache hit rate |
Active Directory domain controller
The default interval for this script is Every 10 minutes.
The default settings for the Advanced tab on the Properties dialog box are overridden for this script. Specifically, the Collapse duplicates option is disabled, and the Raise event if event condition occurs option is set to 3 times within 3 job iterations.
Set the following parameters as needed:
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Parameter |
How to Set It |
|---|---|
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General Settings |
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Raise event if job fails |
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Event severity when job fails |
Set the severity level, from 1 to 40, to indicate the importance of an event in which the CacheHitRate job fails. The default is 35. |
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Monitor cache hit rate |
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Event Notification |
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Raise event if cache hit rate falls below threshold? |
Select Yes to raise an event if the cache hit rate falls below the threshold you set. The default is Yes. |
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Threshold -- Minimum cache hit rate |
Specify the minimum percentage of time that requested data should be found in the cache before an event is raised. The default is 93%. |
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Event severity when cache hit rate falls below threshold |
Set the severity level, from 1 to 40, to indicate the importance of an event in which the cache hit rate falls below the threshold. The default is 20. |
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Data Collection |
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Collect data for cache hit rate? |
Select Yes to collect data for charts and reports. If enabled, data collection returns the name cache hit rate for the interval. By default, data is not collected. |