How to Back Up UGREEN NAS to an External Hard Drive

Connect an external hard drive or USB drive to your UGREEN NAS and use Sync & Backup to copy selected NAS folders to it. Incremental backup is the better default for recovery because deleting a source file does not delete its backup copy; mirror backup repeats the deletion on the destination. If the external drive is meant to provide offline protection, safely eject and disconnect it after the backup or rotate between two drives.

An external-drive backup adds that separate copy. For a broader strategy covering computers, phones, cloud storage, and off-site protection, start with our UGREEN NAS backup guide.

Incremental or Mirror Backup: Which Should You Use?

UGOS Pro offers incremental and mirror modes when backing up NAS folders to a mounted external drive.

For recovery needs, we recommend incremental backup. It preserves the external copy of a file after the source is deleted, giving you a way to recover from accidental deletion.

Choose mirror backup when you need an exact replica of the current source and do not want old files accumulating on the destination. Because deletions are repeated, a mirror should not be your only deleted-file recovery method.

Before You Connect the External Drive

The native Sync & Backup workflow creates a UGREEN .ubk backup package. It is designed to be restored through Sync & Backup on UGOS Pro.

If the original NAS is destroyed, stolen, or unavailable, plan on needing another working UGREEN NAS running UGOS Pro to restore the package.

This creates an important choice:

If your recovery plan must work without a UGREEN NAS, maintain an additional plain-file copy on a drive formatted for the computer you expect to use. A plain-file copy and a .ubk backup serve different purposes and can be kept on separate drives for important data.

Check the External Drive’s File System

UGOS Pro supports these external-storage file systems:

• btrfs
• ext2, ext3, and ext4
• FAT16 and FAT32
• exFAT
• NTFS
• XFS

HFS+ and APFS are not supported. A drive previously used with a Mac may therefore fail to mount until it is reformatted to a supported file system.

Formatting erases the external drive. Copy any existing files elsewhere before reformatting it.

Calculate the Capacity You Need

Use this planning formula:

Required destination capacity = current selected data + expected new, modified, and deleted data retained during the planned backup period

Suppose the selected NAS folders currently contain 8TB and generate approximately 2TB of new or retained changed data each year. Keeping the same incremental backup for two years would require at least:

8TB + (2TB × 2 years) = 12TB

Allow Enough Time for the First Backup

The first run copies the complete selected dataset and can take many hours.

Copying 10TB at a sustained 100 MB/s takes about 27.8 hours before file-system, small-file, and application overhead. At 200 MB/s, the same amount takes about 13.9 hours.

Keep the drive connected and avoid restarting or powering off the NAS during this first full backup.

How to Back Up UGREEN NAS to an External Drive

Once the drive is mounted, has enough capacity, and uses a supported file system, create the task through the UGOS Pro web or desktop interface.

1. Connect and Check the External Drive

Connect the external HDD, SSD, or USB drive to a USB port on the NAS.

Open Storage Manager, select External Storage Management, and confirm that the device appears with the expected capacity and file system. You can also select the device’s menu and open Access Files to view it in Files.

If the drive does not appear, check its power supply, USB cable, file system, and connection before proceeding.

2. Open Backup & Restore

Open Sync & Backup from the UGOS Pro application list.

Select Backup & Restore in the left menu, then click Create backup task.

Choose Back Up Between Storage Pools and click Next. Despite the name, this option also supports a mounted external hard drive or USB drive as the destination.

3. Choose the NAS Folders to Protect

Select Backup Source, then choose one or more folders stored on the NAS.

Include the folders whose loss would matter, such as:

• Family photos and videos
• Work documents
• Creative projects
• Computer backup folders
• Important application exports
• Configuration files needed for recovery

Temporary downloads, replaceable media, cache folders, and generated thumbnails may not justify the additional backup time and capacity.

4. Select the External Drive as the Destination

Under Backup Destination, select the mounted external device and choose the folder where the backup package will be stored.

Verify the source and destination carefully. Selecting the wrong external folder can place the package somewhere you do not expect or create an incomplete recovery plan.

5. Review the Optional Filters

UGOS Pro can exclude files according to size or file type. For example, you can omit temporary .tmp files or application .log files.

Use these filters cautiously. A file-size exclusion can silently omit large videos, disk images, archives, or project files that you intended to protect. If you do not have a specific reason to exclude something, leave the filter disabled.

6. Select Incremental or Mirror Backup

Choose the mode according to the behavior you need:

• Select Incremental Backup to retain the external copy when a source file is deleted.
• Select Mirror Backup to keep the destination identical to the current source.

Incremental backup is the recommended starting point for most home and small-business recovery needs.

7. Set the Backup Schedule

Choose when UGOS Pro should run the task.

A nightly schedule fits data that changes every day. A weekly schedule may be sufficient for a mostly static photo archive. Run large tasks outside active working hours so the backup does not compete with file transfers, media indexing, or other storage-intensive jobs.

A scheduled task can only run while the external drive is connected and mounted. If you normally keep the drive offline, reconnect it before the scheduled time or run the task manually.

8. Review and Create the Task

On the backup preview page:

1. Give the task a recognizable name.
2. Confirm the source folders.
3. Confirm the external-drive destination.
4. Check the selected backup mode.
5. Review the schedule and filters.
6. Select Confirm to create the task.

UGOS Pro will create the task and begin the first backup. Return to Backup & Restore to view its progress, execution history, or run it manually.

Do not assume a task succeeded merely because it started. Check its completion status and review the execution record for skipped files, permission errors, disconnections, or insufficient destination capacity. If the task repeatedly fails, work through our NAS backup failure troubleshooting guide.

How to Test and Restore the USB Backup

A completed task proves that UGOS Pro wrote data to the destination. It does not prove that you can recover the data you need.

For the first test, create a small NAS folder containing several file types, such as a photo, document, and video. Include that folder in the backup task and allow the job to finish.

Then test the restore:

1. Connect and mount the external drive.
2. Open Sync & Backup.
3. Select Backup & Restore.
4. Click Restore.
5. Choose Restore from Backup File.
6. Select Local Folder or USB.
7. Locate the .ubk backup package on the external drive.
8. Select the required backup version.
9. Choose the test folder or files to restore.
10. Start the restoration and monitor it in Task Center.

After the restoration finishes, open each test file. Confirm that photos display correctly, documents are readable, videos play, and file sizes match what you expected.

Repeat a small restore test periodically. Backups can stop working because of a full destination, an unmounted drive, changed permissions, damaged files, or a configuration change made after the original test.

Because .ubk restoration depends on UGOS Pro, your disaster-recovery plan should also answer this question:

If this NAS is no longer available, which replacement UGREEN NAS will you use to restore the package?

If you cannot answer that question, maintain an additional platform-independent copy of your most important files.

Should You Leave the External Drive Connected?

Leaving the external drive connected makes scheduled backups easy, but it does not provide the same protection as an offline copy.

A permanently connected external drive can still be deleted, corrupted, or reformatted by someone with sufficient access to the NAS. It also remains in the same physical environment as the NAS during a power event, theft, fire, or flood.

For stronger isolation, rotate two drives:

1. Connect Drive A and complete the backup.
2. Verify the task and perform a small restore test.
3. Safely eject Drive A before unplugging it.
4. Store Drive A disconnected, preferably at another secure location.
5. Connect Drive B for the next backup cycle.
6. Continue rotating the drives.

To eject a drive, open Storage Manager > External Storage Management, select the device’s menu, and choose Eject. Wait for UGOS Pro to confirm that the operation has completed before unplugging it.

Directly removing the drive while it is writing can corrupt files or lose data. This risk is greater if ext4 delayed allocation has been enabled to improve external-drive write performance.

Is the External Backup Encrypted?

Sync & Backup does not expose a package-encryption setting for this external-drive task. Treat the .ubk package as unencrypted unless you have separately verified protection for the destination.

This matters most when a drive leaves your home or office. Someone who obtains an unencrypted off-site drive may be able to access its data or backup package.

Do not move the only copy of important files into UGREEN NAS Safes as a workaround. Files inside Safes are not supported by Sync & Backup.

What an External-Drive Backup Does Not Cover

A USB backup is a strong local recovery layer, but it is not a complete backup plan by itself.

It cannot fully protect you when:

• The only external drive fails.
• The connected backup is deleted by an administrator or malicious process.
• The NAS and backup drive are stolen or damaged together.
• Mirror mode repeats an accidental deletion.
• The destination fills and later jobs cannot complete.
• Live databases or containers are copied without an application-consistent backup.
• The backup package exists but has never been tested through a restore.
• The original NAS is unavailable and no replacement UGOS Pro system is ready.

For irreplaceable files, maintain three copies on at least two storage types, with one copy stored off-site. The NAS can hold the working data, an external drive can provide the local backup, and an independent remote destination can provide disaster recovery. Our automated NAS-to-cloud backup guide covers that off-site layer.

Whichever arrangement you use, the backup is not complete until you have restored files from it successfully.