Monitors for a significant decrease of database free space over a number of sample periods. Note: This monitor is disabled by default. Please use overrides to enable it when necessary.
Knowledge Base article:
Summary
Monitors for a significant decrease of database free space over a number of sample periods. A rapid large change in value could indicate a problem.
Causes
An unhealthy state is caused by a large change in free space over a set number of sample periods. This can be caused by:
A large autogrowthth setting for a file set to autogrowth.
A fast growing file that consumed a large amount of free space within a short period.
A foreign object or file consumed a large amount of free space hosted on the same disk as this file
Use the following link to view the performance data: Database Performance Data
This monitor aggregates the space available for each file within a Filegroup depending on each file’s configuration:
No Autogrowth
For a file that has no autogrowth, free space would be the difference between the initial size for a file and the used space.
Autogrowth Enabled
In addition to the difference between the file size and the used space, the free space for files with autogrowth enabled would be the minimum of either the difference between the max size and the file size and the free space left on disk.
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.
Resolutions
This issue may be resolved by either:
Decreasing the growth amount for files with autogrowth
Modifying the thresholds for this monitor to suit the workload
Alternatively if space percentage change is not a concern for the database:
Disable this monitor for this specific database or all databases
Overridable Parameters
Name
Description
Default Value
Alert Priority
Defines Alert Priority.
Normal
Alert Severity
Defines Alert Severity.
MatchMonitorHealth
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 exceeds this threshold. Being between this threshold and the warning threshold (inclusive) will result in the monitor being in a warning state.
45
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.
900
Number of samples
Indicates how many times a measured value should breach a threshold before the state is changed.
5
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
Warning threshold. Exceeding this threshold will result in the monitor changing to at least a warning state.
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