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QNAP Warning: “Storage Capacity Below X%” – Causes and How to Adjust the Alert Threshold

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Problem Overview

Your QNAP NAS displays a warning like:

“System free space has dropped below 20%”
or
“Warning: The free space on volume DataVol1 is below the threshold”

This alert means the available storage on one of your volumes or system partitions has dropped below the defined warning level – typically set to 20% by default. Ignoring it can result in:

• Failed backups or sync jobs

• Loss of camera recordings

• Disabled snapshots

• Malfunctioning apps or system services (e.g. Virtualization Station, Plex)

Possible Causes

1. Unexpected data growth
   – Automatic backups, video surveillance data, or large transfers

2. Recycle bin is enabled
   – Deleted files still occupy space

3. Snapshots or TimeMachine backups grow silently
   – May consume hundreds of GB over time

4. Log files or app-generated temp data
   – Created by apps like Surveillance Station or Container Station

5. Small system volume configuration
   – Often the case with SSD/HDD hybrid setups

Solution: Adjust the Warning Threshold

If you're aware of the current data growth and don't want constant alerts, you can customize the threshold for disk space warnings. This lets QNAP alert you only when space falls below a percentage that suits your environment.

How to Adjust the Capacity Alert Level

1. Log in to QTS

Use an administrator account to access the QNAP web interface.

2. Go to:

Control Panel → System Settings → Notifications → Event Notifications

• Scroll down and click “Advanced Settings”

3. Modify the alert setting

• Find the event:

  “System volume storage space has dropped below XX%”

• Click the edit icon

• Enter your preferred % value (e.g. 30%, 15%, 10%)

• Save changes

Configure Notifications

Email Notifications

• Go to Notifications → Email

• Set up your SMTP server (e.g. Gmail, Outlook)

• Test the connection

• Define one or more recipient addresses

Push Notifications (Qmanager App)

• Under Push Service, enable alerts to mobile

• Connect your mobile device using Qmanager

Optional Channels

• SMS via API (ClickSend, Nexmo, etc.)

• Telegram, Microsoft Teams, or LINE via the QNAP Notification Center

Recommended Thresholds

Storage Cleanup Tips

• Delete old snapshots

• Empty the recycle bin (or disable it entirely)

• Review logs from heavy apps (e.g. Docker containers)

• Use Storage & Snapshots to monitor space consumption

Conclusion

When your QNAP NAS warns you about low disk space, don’t ignore it. Review the current storage usage, free up space where needed, and adjust the alert threshold to match your needs. With proper configuration, you’ll stay informed and prevent system downtime or data loss.