cp: error writing 'synoboot_mount/extra2.lzma': no space left on device

3 min read 26-02-2025

The error message "cp: error writing 'synoboot_mount/extra2.lzma': No space left on device" indicates a critical issue on your Synology NAS (Network Attached Storage) system. It means you've run out of available storage space on the partition where the extra2.lzma file is being written. This file is crucial for your system's boot process and data integrity. Ignoring this error can lead to system instability and potential data loss.

Understanding the Error

The command cp (copy) attempts to copy or write the extra2.lzma file to the synoboot_mount partition. This partition typically holds essential system files. The "no space left on device" part clarifies the root cause: your NAS's storage is completely full. There's no room for the system to perform the necessary operation, creating this error.

Causes of the Error

Several factors contribute to this error:

Full Storage: The most obvious reason is that your Synology NAS's hard drive(s) or SSD(s) have reached their storage capacity. This is often gradual, starting with warnings about low space before ultimately failing.
Large Files: Downloading or uploading exceptionally large files without enough free space can trigger the error.
System Logs: Continuously growing system logs can consume significant storage over time.
Data Backups: Frequent and extensive data backups can quickly fill up the available space if not managed properly.
Software Updates: Large software updates require sufficient free space for installation. If the space is insufficient, the update process might fail.
Multimedia Files: Storing large numbers of photos, videos, or music files without regular cleanup can easily exceed storage limits.

Troubleshooting Steps

Here's how to resolve the "cp: error writing 'synoboot_mount/extra2.lzma': no space left on device" error:

1. Identify the Problem Area:

Use the Synology DSM (DiskStation Manager) interface to check your storage usage. Look at the overall storage capacity and the space used by each shared folder or application. This helps pinpoint the culprit.

2. Free Up Disk Space:

This is the most crucial step. To free up space:

Delete Unnecessary Files: Remove old, unused files, photos, videos, or documents. Be thorough; review each folder carefully.
Empty Recycle Bin: Regularly emptying the recycle bin can reclaim a surprising amount of space.
Uninstall Unused Packages: If you have applications you no longer need, uninstall them through DSM's Package Center.
Review System Logs: Consider rotating or clearing out older system logs to prevent them from overwhelming your storage. Check your DSM settings for log management.
Move Data to External Storage: If possible, move less-frequently accessed files or backups to an external hard drive or cloud storage.
Check for Corrupted Files: Use DSM's tools to scan for and remove corrupted files, freeing up wasted space.

3. Check and Manage Backups:

Ensure your backup strategy isn't creating excessive copies of data. Configure backups to delete old versions automatically to prevent storage exhaustion.

4. Check for Software Updates:

Ensure enough free space is available before initiating a major system or package update. A failed update can severely compromise your system.

5. Consider Expanding Storage:

If freeing up space isn't feasible, expand your NAS's storage capacity. This might involve adding more hard drives or SSDs, depending on your Synology model. Follow Synology's documentation for safe storage expansion procedures.

6. If the Problem Persists:

If you've tried all the above and still encounter the error, contact Synology support. The problem could stem from a more severe system issue requiring professional assistance.

Prevention

To prevent this issue in the future:

Regularly Monitor Storage Usage: Use DSM to keep track of storage levels. Set up alerts to warn you when space gets low.
Implement a Backup Strategy: Implement a reliable backup strategy to regularly back up your important data. This safeguards your information in case of storage failure.
Regularly Purge Unnecessary Files: Make deleting unused files a routine task to prevent storage overload.
Use Cloud Storage: For frequently used data or files that are important but not accessed regularly, consider offloading data to cloud services.

The "cp: error writing 'synoboot_mount/extra2.lzma': no space left on device" error is serious. Address it promptly to avoid potential data loss and maintain system stability. By following these steps and adopting preventative measures, you can keep your Synology NAS running smoothly.