Virtual Log File Count

Microsoft.SQLServer.Windows.Monitor.Database.VLFCount (UnitMonitor)

Virtual Log File Count monitor for SQL DBs on Windows. Note: This monitor is disabled by default. Use overrides to enable it when necessary.

Knowledge Base article:

Summary

Virtual Log File count monitor for SQL DB

Causes

An unhealthy state is caused by having many Virtual Log Files for a database. Many Virtual Log Files can be caused by small size and 'growth_increment' values.

Use the following link to view the performance data:

Database Performance Data

This monitor counts Virtual Log Files for a database.

Resolutions

This issue may be resolved by either:

Backing up the transaction log, shrinking a transaction log file with the DBCC SHRINKFILE command and setting Autogrow to a larger increment
Modifying the thresholds for this monitor to suit the workload
Alternatively if Virtual Log File count is not a concern for the database:
- Disable this monitor for this specific database or all databases

See SQL Server Books Online: Transaction Log Physical Architecture

Overridable Parameters

Name	Description	Default Value
Alert Priority	Defines Alert Priority.	Normal
Alert Severity	Defines Alert Severity.	Error
Enabled	Enables or disables the workflow.	No
Generates Alerts	Defines whether the workflow generates an Alert.	Yes
Interval (seconds)	The recurring interval of time in seconds in which to run the workflow.	300
Number of samples	Indicates how many times a measured value should breach a threshold before the state is changed.	6
Warning Threshold	The collected value will be compared against this parameter.	100
Critical Threshold	The collected value will be compared against this parameter.	1000
Timeout (seconds)	Specifies the time the workflow is allowed to run before being closed and marked as failed.	200

Element properties:

Target

Microsoft.SQLServer.Windows.Database

Parent Monitor

System.Health.PerformanceState

Category

PerformanceHealth

Enabled

False

Alert Generate

True

Alert Severity

MatchMonitorHealth

Alert Priority

Normal

Alert Auto Resolve

True

Monitor Type

Microsoft.SQLServer.Windows.MonitorType.Database.VLFCount

Remotable

True

Accessibility

Public

Alert Message

MSSQL on Windows: Many Virtual Log Files

There are many virtual log files for database "{0}" on SQL Server instance "{1}", computer "{2}". See the "Alert Context" tab for more details.

RunAs

Default

Source Code:

<UnitMonitor ID="Microsoft.SQLServer.Windows.Monitor.Database.VLFCount" Accessibility="Public" Enabled="false" Target="SqlDiscW!Microsoft.SQLServer.Windows.Database" ParentMonitorID="Health!System.Health.PerformanceState" Remotable="true" Priority="Normal" TypeID="Microsoft.SQLServer.Windows.MonitorType.Database.VLFCount" ConfirmDelivery="false">

  <Category>PerformanceHealth</Category>

  <AlertSettings AlertMessage="Microsoft.SQLServer.Windows.Monitor.Database.VLFCount.AlertMessage">

    <AlertOnState>Warning</AlertOnState>

    <AutoResolve>true</AutoResolve>

    <AlertPriority>Normal</AlertPriority>

    <AlertSeverity>MatchMonitorHealth</AlertSeverity>

    <AlertParameters>

      <AlertParameter1>$Target/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.Database"]/DatabaseName$</AlertParameter1>

      <AlertParameter2>$Target/Host/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/InstanceName$</AlertParameter2>

      <AlertParameter3>$Target/Host/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/MachineName$</AlertParameter3>

    </AlertParameters>

  </AlertSettings>

  <OperationalStates>

    <OperationalState ID="Normal" MonitorTypeStateID="Normal" HealthState="Success"/>

    <OperationalState ID="Warning" MonitorTypeStateID="Warning" HealthState="Warning"/>

    <OperationalState ID="Error" MonitorTypeStateID="Error" HealthState="Error"/>

  </OperationalStates>

  <Configuration>

    <MachineName>$Target/Host/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/MachineName$</MachineName>

    <NetbiosComputerName>$Target/Host/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/NetbiosComputerName$</NetbiosComputerName>

    <InstanceName>$Target/Host/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/InstanceName$</InstanceName>

    <DatabaseName>$Target/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.Database"]/DatabaseName$</DatabaseName>

    <WarningThreshold>100</WarningThreshold>

    <CriticalThreshold>1000</CriticalThreshold>

    <ConnectionString>$Target/Host/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/ConnectionString$</ConnectionString>

    <InstanceVersion>$Target/Host/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/Version$</InstanceVersion>

    <InstanceEdition>$Target/Host/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/Edition$</InstanceEdition>

    <MonitoringType>$Target/Host/Property[Type="SqlDiscW!Microsoft.SQLServer.Windows.DBEngine"]/MonitoringType$</MonitoringType>

    <IntervalSeconds>300</IntervalSeconds>

    <SyncTime/>

    <TimeoutSeconds>200</TimeoutSeconds>

    <SqlTimeoutSeconds>15</SqlTimeoutSeconds>

  </Configuration>

</UnitMonitor>