How to Replace a Failing Drive in UGREEN NAS

Do not remove a drive until you have confirmed its bay number, serial number, and storage-pool status in UGOS Pro. For this replacement procedure, shut down and unplug the NAS before removing the drive tray.

A Degraded RAID 1, RAID 5, RAID 6, or RAID 10 pool can generally be repaired with a healthy compatible replacement drive. Basic, JBOD, and RAID 0 cannot reconstruct missing data after a member fails.

Check the Storage Pool State Before Removing a Drive

Open the Storage app and check the affected drive and storage pool. 

If you have not confirmed that the drive itself is failing, follow our guide to diagnosing a UGREEN NAS drive failure before continuing.

If the pool is still readable and you do not have a current independent backup, copy the most important files before starting a repair. Rebuilding a degraded array reads heavily from the surviving drives and can expose another weak member.

Confirm Which Physical Drive Is Failing

Removing the wrong drive from a degraded pool can turn a recoverable failure into an unavailable array.

Open Storage > Hard Drive > HDD/SSD and record:

• The drive number and bay
• The drive’s model and serial number
• Its health status
• The storage pool that uses it
• Its power-on time
• Any recent disconnection or bad-sector warnings

On DXP models, open the drive’s action menu and select Locate hard drive. The indicator for the corresponding slot will turn green and blink for the selected duration.

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DH and DH Plus models do not support the same Locate function. Identify the drive manually using its drive number, physical slot order, serial number, and storage-pool information.

Stop if two drives appear missing, their positions do not match your records, or you cannot confidently identify the affected member.

Can You Hot-Swap a UGREEN NAS Drive?

UGREEN NAS supports hot-swapping of hard drives, but we recommend powering it down before swapping drives to ensure data safety.

Follow this sequence:

1. Shut down the NAS through UGOS Pro.
2. Wait until the system is fully powered off.
3. Disconnect the power cable.
4. Remove and replace the drive.
5. Reconnect power and restart the NAS.

M.2 SSDs must also be handled with the NAS powered off. If an M.2 SSD is being used as cache, remove the cache configuration in UGOS Pro before removing the device. Otherwise, cached data may be lost.

Choose a Replacement Drive the Pool Can Accept

Check the exact model number against the UGREEN NAS compatibility list. Matching the brand name or advertised capacity alone is not enough.

The replacement drive must meet these requirements:

• Its capacity must be equal to or greater than the failed member.
• It must report a healthy status.
• UGOS Pro must show it as Unused.
• Its interface and sector format must be compatible with the NAS and storage pool.
• Any existing data on the replacement must be expendable because Repair formats the drive.

A larger replacement does not immediately increase RAID capacity. For example, replacing one 8TB member with a 12TB drive still gives the array 8TB from that position. The additional 4TB remains unavailable until the remaining members are upgraded and the pool is expanded through a supported process.

A drive sold under the same nominal capacity can also expose a slightly different number of sectors. Using the same model or a confirmed compatible equal-or-larger drive reduces the risk of UGOS Pro rejecting it as too small.

For an HDD array, start with a compatible NAS-rated CMR drive. Our guide to choosing drives for a UGREEN NAS covers specific models, workload ratings, noise, warranty, and CMR versus SMR.

Test the Replacement Before Repair

The safest replacement is a compatible cold spare that has already passed a complete SMART test and full surface scan. This catches a defective new drive before the storage pool depends on it.

If the pool is already Degraded and no pretested spare is available:

1. Confirm that important data is independently backed up.
2. Install the replacement with the NAS powered off.
3. Confirm that UGOS Pro shows the drive as healthy and Unused.
4. Review its SMART information.
5. Run a rapid status test.
6. Begin the repair promptly if the test passes.

A complete pre-repair test is worthwhile when you can run it in another system or unused bay without extending the time the pool remains degraded. Making a damaged RAID 1 or RAID 5 pool wait another day for a full burn-in can create its own risk.

Keeping a tested replacement drive on hand is the better long-term solution, especially for four-, six-, or eight-bay arrays.

Replace the Drive and Repair the Storage Pool

The procedure changes slightly depending on whether the original pool is still Normal or is already Degraded.

The Pool Is Normal, but a Drive Is Failing

When the drive remains online and the pool is Normal, an unused bay provides the safest planned-replacement path.

1. Back up important data.
2. Shut down the NAS and disconnect power.
3. Install the tested replacement in an unused bay.
4. Reconnect power and start the NAS.
5. Open Storage > Hard Drive > HDD/SSD.
6. Select the new drive, which should appear as Unused.
7. Choose Use > Replace Hard Drive in the Storage Pool.
8. Select the storage pool and the member being replaced.
9. Confirm the operation and allow UGOS Pro to complete the replacement.
10. Remove the original drive only after the task finishes and the storage pool reports Normal.

This workflow requires a free drive bay.

If every bay is occupied, confirm the backup, select the failing member in Storage > Hard Drive, and use Disable before shutting down and replacing it. Disabling a member causes a redundant pool to become Degraded, so do not use this action if the pool is already Degraded or has reached its fault-tolerance limit.

The Pool Is Already Degraded

When UGOS Pro has already removed or disabled the failed member, replace it in the same bay and repair the pool.

1. Confirm that the pool is Degraded rather than Critical or Damaged.
2. Record the failed drive’s bay, model, and serial number.
3. Shut down the NAS through UGOS Pro.
4. Wait until the system is fully powered off.
5. Disconnect the power cable.
6. Unlock the affected drive tray and pull it straight out.
7. Remove the failed drive from the tray.
8. Install the compatible replacement in the same tray.
9. Reinsert and lock the tray in the original bay.
10. Reconnect power and start the NAS.
11. Open Storage > Hard Drive > HDD/SSD.
12. Confirm that the replacement appears as healthy and Unused.
13. Review its SMART information and run a rapid status test.
14. Select the replacement drive and choose Use > Repair Storage Pool.
15. Select the Degraded pool and apply the repair.
16. Confirm the warning that the replacement drive will be formatted.
17. Monitor the task until the storage pool returns to Normal.

For a 3.5-inch HDD, align the side holes with the tray’s mounting pins and lock the clamp arm in place. For a 2.5-inch drive, align the bottom mounting holes and secure the drive with the required screws.

Do not create a new storage pool on the replacement drive. That assigns the drive to separate storage instead of using it to restore the degraded array.

What Happens During RAID Repair?

UGOS Pro reconstructs the missing member by reading data and parity from the surviving drives and writing the result to the replacement. File access can remain available while the storage space is mounted, but performance will be lower.

For a drive above 10TB, reserve at least a full day. A repair can take 10 to 20 hours, and busy systems or arrays with weak surviving drives can take longer.

While repair is running:

• Do not remove or replace another drive.
• Avoid large file transfers, media indexing, virtual machines, and other heavy workloads.
• Do not run complete SMART tests on participating drives.
• Do not update UGOS Pro or restart the NAS.
• Keep the NAS connected to stable power, preferably through a communicating UPS.
• Watch drive temperatures and system notifications.
• Wait for 100% completion and a Normal pool status before considering the repair finished.

Heavy workloads compete with the repair for drive access, increase temperatures, and extend the time the pool remains degraded. On RAID 1 or RAID 5, that longer repair window leaves the array exposed to another drive failure or an unreadable sector on a surviving member.

RAID 6 retains protection against one additional failure after losing its first member. RAID 10 tolerance depends on which mirror members fail. Regardless of RAID level, another drive warning during repair requires immediate attention.

Why the Repair Option May Be Missing

Do not initialize or format drives at random when UGOS Pro does not offer the expected repair action.

A Basic, JBOD, or RAID 0 pool will not offer a redundancy-based repair after a member fails. Replace the failed hardware, recreate the storage configuration, and restore the data from an independent backup.

After the Storage Pool Returns to Normal

Confirm all three results before resuming normal workloads:

1. The replacement drive reports a Normal health status.
2. The storage pool and storage space both report Normal.
3. Important files open correctly and the independent backup is current.

Record the replacement drive’s:

• Model
• Serial number
• Bay number
• Installation date
• SMART test result

Keep this information in a NAS maintenance log or save a photo of the drive label. During a future warning, this record will show which members are relatively new and which have accumulated years of operation.

If the NAS has an unused bay, a Hot Spare can shorten the time between a future drive failure and the start of repair. UGOS Pro supports HDD hot spares for RAID 1, RAID 5, RAID 6, and RAID 10. The spare must be at least as large as the smallest pool member, its existing data will be erased, and the storage pool must be Normal when the spare is configured.