Fix ERROR_CLUSTERLOG_NOT_ENOUGH_SPACE (0X000013A9)

Quick answer

Free at least 500 MB on the system drive, or move the cluster diagnostic log location to another volume using Get-ClusterDiagnosticLogPath and Set-ClusterDiagnosticLogPath in PowerShell.

Why this happens

Windows Failover Cluster writes diagnostic logs to C:\Windows\Cluster\Reports by default. When the system drive (usually C:) drops below the minimum free space threshold — 512 MB on Server 2012 R2 and later — the cluster service refuses to write new entries. You'll see event ID 1196 with error code 0X000013A9. This is a safety mechanism: the cluster won't fill the drive completely and risk crashing the OS or other services. I've seen this happen most often after a failed backup job or a runaway log file from another application eats up the last few hundred MB.

Fix steps

Check free space on the system drive. Run fsutil volume diskfree C: from an elevated command prompt. If it's under 1 GB, that's your problem.
Free up space. Delete old Windows Update cache (Dism /Online /Cleanup-Image /StartComponentCleanup /ResetBase), clear the Recycle Bin, move user profiles or pagefile to another disk if needed. I'd aim for at least 2 GB free to give the cluster room to breathe.
Move the cluster log folder if you can't free enough space quickly. This is the real fix when C: is chronically cramped.
```
Get-ClusterDiagnosticLogPath
Set-ClusterDiagnosticLogPath -Path "D:\ClusterLogs"
```
The reason step 3 works is that the cluster service reads the log location from a registry value under HKLM\Cluster\Diagnostics\LogPath. The Set-ClusterDiagnosticLogPath cmdlet updates that value and moves existing logs. You don't need to restart the cluster.
Restart the cluster service only if the error persists after step 3. Run Stop-Service ClusSvc; Start-Service ClusSvc. In my experience, the change takes effect immediately without a restart, but I've seen one case where a reboot was needed — Server 2016 with KB4013429.

Alternative fix: Increase the log size

The cluster log grows to a max of 1 GB by default. If you have a dedicated disk for logs, you can bump that up to 2 GB. But don't do this on C:. Run this from an elevated PowerShell:

Set-ClusterDiagnosticLogSize -Size 2048

This only helps if you've already moved the log folder off the system drive.

Prevention

Don't rely on C: for cluster logging. Move the log folder to a dedicated volume (100 GB minimum) during cluster setup. The registry key HKLM\Cluster\Diagnostics\LogPath persists across reboots, so it's a one-time config. Also monitor free space on C: with a threshold of 5 GB — set an alert in Performance Monitor or your favorite monitoring tool. When C: hits 5 GB, you've got time to act before the cluster stops logging.