The monitor reports a warning when the free space (including both already allocated space and free space on the media) drops below the Warning Threshold setting, expressed as percentage of the sum of data size plus disk free space. The monitor reports a critical alert when the free space drops below the Critical Threshold.
The monitor oversees the space available in the file and on the media which hosts the file. The space available on the media is only considered if auto grow is enabled for the given file.
An unhealthy state is caused by having low available for this file. Low free space can be caused by:
Inadequate file configuration settings (size, max size, auto grow, etc.)
Inadequate space left on media
Use the following link to view the performance data: DB File Free Space Performance Data
No Auto Grow
For a file that has no auto grow, free space would be the difference between the initial size for a file and the used space.
Auto Grow Enabled
With auto grow enabled, the available disk space is included as part of the over free space. In addition to the difference between the file size and the used space, the free space for files with auto grow enabled would be the minimum of either the difference between the max size and the file size and the free space left on disk.
Low free space for database files that have auto grow could mean that the file is approaching the limits of the hosting logical drive. For files with auto grow enabled with a max size, low free space could also mean that the file is approaching the max size specified for a file.
The free space calculations also take into account that the file can also fail to grow if the growth amount of the file is greater than the amount left on disk and that the file cannot grow if the difference between the max size and the current file size is less than the growth amount. In these situations, available free space left on disk is not included as part of the free space because we cannot grow any longer.
This issue may be resolved by either:
Increasing the allocated size for a file or all files within a Filegroup if auto grow is disabled
Increasing the max size value for a file if auto grow is enabled
Enabling auto grow for at least one file
Moving files to another drive with more free space if growth space is limited
Modifying the thresholds for this monitor to suit the workload
Alternatively if Filegroup free space is not a concern for the database:
Disable this monitor for this specific Filegroup or all Filegroups
See SQL Server Books Online: Files and Filegroups Architecture
Name | Description | Default Value |
Alert Priority | Defines Alert Priority. | Normal |
Alert Severity | Defines Alert Severity. | Error |
Azure Maximum File Size (MB) | The maximum size of data file stored in Azure BLOB Storage. The workflow will consider this value as a maximum storage capacity for each file. | 1048576 |
Critical Threshold | The monitor will change its state to Critical if the value drops below this threshold. Being between this threshold and the warning threshold (inclusive) will result in the monitor being in a warning state. | 10 |
Enabled | Enables or disables the workflow. | Yes |
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. | 900 |
Synchronization Time | The synchronization time specified by using a 24-hour format. May be omitted. |
|
Timeout (seconds) | Specifies the time the workflow is allowed to run before being closed and marked as failed. | 300 |
Warning Threshold | The monitor will change its state to Warning if the value drops below this threshold. | 20 |
Target | Microsoft.SQLServer.2016.DBFile | ||
Parent Monitor | System.Health.PerformanceState | ||
Category | PerformanceHealth | ||
Enabled | True | ||
Alert Generate | True | ||
Alert Severity | Error | ||
Alert Priority | Normal | ||
Alert Auto Resolve | True | ||
Monitor Type | Microsoft.SQLServer.2016.DBFileSizeMonitorType | ||
Remotable | True | ||
Accessibility | Public | ||
Alert Message |
| ||
RunAs | Default |
<UnitMonitor ID="Microsoft.SQLServer.2016.Monitoring.DBFileSpaceMonitor" Accessibility="Public" Enabled="true" Target="SQL2016Core!Microsoft.SQLServer.2016.DBFile" ParentMonitorID="SystemHealth!System.Health.PerformanceState" Remotable="true" Priority="Normal" TypeID="Microsoft.SQLServer.2016.DBFileSizeMonitorType" ConfirmDelivery="true">
<Category>PerformanceHealth</Category>
<AlertSettings AlertMessage="Microsoft.SQLServer.2016.Monitoring.DBFileSpaceMonitor.AlertMessage">
<AlertOnState>Error</AlertOnState>
<AutoResolve>true</AutoResolve>
<AlertPriority>Normal</AlertPriority>
<AlertSeverity>Error</AlertSeverity>
<AlertParameters>
<AlertParameter1>$Target/Property[Type="SQL2016Core!Microsoft.SQLServer.2016.File"]/FileName$</AlertParameter1>
<AlertParameter2>$Target/Host/Property[Type="SQL2016Core!Microsoft.SQLServer.2016.FileGroup"]/GroupName$</AlertParameter2>
<AlertParameter3>$Target/Host/Host/Property[Type="SQL2016Core!Microsoft.SQLServer.2016.Database"]/DatabaseName$</AlertParameter3>
<AlertParameter4>$Target/Host/Host/Host/Property[Type="SQL2016Core!Microsoft.SQLServer.2016.ServerRole"]/InstanceName$</AlertParameter4>
<AlertParameter5>$Target/Host/Host/Host/Host/Property[Type="Windows!Microsoft.Windows.Computer"]/NetworkName$</AlertParameter5>
</AlertParameters>
</AlertSettings>
<OperationalStates>
<OperationalState ID="UnderThreshold1" MonitorTypeStateID="UnderThreshold1" HealthState="Error"/>
<OperationalState ID="OverThreshold1UnderThreshold2" MonitorTypeStateID="OverThreshold1UnderThreshold2" HealthState="Warning"/>
<OperationalState ID="OverThreshold2" MonitorTypeStateID="OverThreshold2" HealthState="Success"/>
</OperationalStates>
<Configuration>
<IntervalSeconds>900</IntervalSeconds>
<SyncTime/>
<ConnectionString>$Target/Host/Host/Host/Property[Type="SQL2016Core!Microsoft.SQLServer.2016.DBEngine"]/ConnectionString$</ConnectionString>
<ServerName>$Target/Host/Host/Host/Host/Property[Type="Windows!Microsoft.Windows.Computer"]/NetworkName$</ServerName>
<SqlInstanceName>$Target/Host/Host/Host/Property[Type="SQL2016Core!Microsoft.SQLServer.2016.ServerRole"]/InstanceName$</SqlInstanceName>
<ObjectName>SQL DB File</ObjectName>
<CounterName>DB File Free Space (%)</CounterName>
<InstanceName/>
<DatabaseName>$Target/Host/Host/Property[Type="SQL2016Core!Microsoft.SQLServer.2016.Database"]/DatabaseName$</DatabaseName>
<DBFileId>$Target/Property[Type="SQL2016Core!Microsoft.SQLServer.2016.File"]/FileID$</DBFileId>
<Value>$Data/Property[@Name='FreeSpacePercent']$</Value>
<Threshold1>10</Threshold1>
<Threshold2>20</Threshold2>
<TimeoutSeconds>300</TimeoutSeconds>
<AzureMaxFileSizeMB>1048576</AzureMaxFileSizeMB>
</Configuration>
</UnitMonitor>