How to Expand UGREEN NAS Storage: Add or Replace Drives

When a UGREEN NAS begins running out of space, the correct expansion method depends on its current storage pool:

• Add an unused compatible drive when UGOS Pro displays the Add to Storage Pool option.
• Change RAID type when the current pool follows a supported conversion path, such as Basic to RAID 1 or RAID 1 to RAID 5.
• If every bay is occupied, expand RAID 1, RAID 5, RAID 6, or RAID 10 by replacing every member with a larger drive, one at a time.

Basic can change to RAID 1 or RAID 5 on supported UGOS Pro versions, while JBOD and RAID 0 must be backed up and recreated.

LD; DR

• NAS storage expansion depends on the current storage pool type. You can add compatible drives, change supported RAID types, or replace all RAID members with larger drives depending on your existing configuration.
• Prepare before expanding a storage pool. Confirm pool health, drive compatibility, backups, stable power, and drive-test results before adding or replacing any drives.
• RAID expansion and rebuilds require patience and caution. Keep the NAS powered on, avoid removing multiple drives, and limit heavy workloads while UGOS Pro repairs or converts the storage pool.
• Adding larger drives one by one is the method for full RAID capacity upgrades. Replace each RAID member individually, repair the pool after every replacement, and expand the volume after all drives are upgraded.
• Verify the entire storage system after expansion. Check pool status, volume capacity, drive health, shared folders, applications, and backups before returning to normal use.

Check These Requirements Before Adding or Replacing Drives

Storage pool health

Open Storage > Storage Pool & Volume and review the pool status. If the NAS reports a failed member, follow the procedure for replacing a failing UGREEN NAS drive. Capacity expansion is not a substitute for repairing a degraded pool.

Drive compatibility

For an HDD array, use compatible NAS-rated CMR drives whenever possible. Check every new HDD or SSD against the UGREEN NAS compatibility list. Match the complete model number, not only the manufacturer, capacity, or product family.

Replacement-drive capacity and sector format

A replacement drive must be at least as large as the member it replaces. Installing one larger drive does not immediately increase RAID capacity;

Also review whether the existing drives use 512e or 4Kn sectors. Mixing unsupported sector formats can prevent a replacement drive from joining the pool.

New-drive testing

Run a complete health or surface test on every new drive before placing it into a degraded array. If the NAS has an empty bay, install the unused drive and run the Status test from Storage > Hard Drive > Status test .

Existing-drive health

Review the SMART results, bad-sector history, temperature, power-on hours, and warning status of every surviving drive. A one-by-one expansion forces the remaining members to sustain repeated full-array reads.

If several drives came from the same production batch and have similar power-on hours, one failure may be the first sign of broader age-related risk.

Independent backup

RAID rebuild and conversion operations are designed to preserve data, but they are not backups. A second drive failure, unreadable sector, power interruption, or filesystem problem can still make the pool inaccessible.

Create and test an independent copy before starting. For an offline copy, follow the process to back up a UGREEN NAS to an external drive.

Stable power and scheduling

Connect the NAS to a compatible UPS if possible. Do not begin immediately before travel, electrical work, or another period when you cannot monitor the system.

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A drive larger than 10TB can take 10 to 20 hours or longer to rebuild. Replacing all four members of a four-drive array can therefore occupy three to four days.

Label each drive with its bay number before removing anything, and record the serial number and installation date of each replacement.

How to Add a Drive to an Existing UGREEN NAS Storage Pool

Use this method when the NAS has an empty bay and UGOS Pro recognizes the current storage pool as eligible for expansion.

1. Shut down the NAS and disconnect its power.
2. Install the compatible unused drive in the empty bay.
3. Reconnect power and start the NAS.
4. Open Storage > Hard Drive.
5. Find the new drive and verify that its status is Unused and its health information is normal.
6. Open the drive’s menu and select Use > Add to Storage Pool.
7. Select the eligible storage pool.
8. Review the warning that existing data on the added drive will be erased.
9. Apply the change and enter the administrator password if prompted.
10. Monitor the operation until the storage pool returns to Normal.

Do not restart or power off the NAS while the pool is expanding.

The Add to Storage Pool option appears only when UGOS Pro determines that the installed drive and current storage pool support this path. If the option is absent, do not try to force the expansion by removing another member or changing drive partitions manually. Use the decision table above to determine whether a RAID change or one-by-one replacement is required.

After the storage pool expands, review the volume capacity. The pool and volume are separate layers, so the volume may not claim the new space automatically.

To expand it:

1. Open Storage > Storage Pool & Volume.
2. Open the menu for the volume.
3. Select Storage pool expansion.
4. Set the new capacity, up to the available maximum.
5. Apply the change and wait for it to finish.

How to Change RAID Type When Adding Drives

With matched 8TB drives, Basic to RAID 1 provides 8TB of decimal usable capacity. Basic to RAID 5 or RAID 1 to RAID 5 with three total 8TB drives provides 16TB before system and filesystem overhead.

Before starting, compare the capacity, write performance, and failure tolerance in our guide to choosing RAID for a NAS. Changing a Basic pool to RAID 1 prioritizes redundancy, while changing to RAID 5 also increases usable capacity.

To use a supported conversion path:

1. Update UGOS Pro if the NAS is running an earlier version.
2. Install the required compatible unused drive or drives.
3. Open Storage > Storage Pool & Volume.
4. Open the menu for the current storage pool.
5. Select Change RAID Type.
6. Select the new RAID type.
7. Select the unused drive or drives that will join the pool.
8. Review the capacity and data-erasure warning.
9. Apply the change.
10. Keep the NAS powered on until the process finishes and the pool returns to Normal.

The added drives will be formatted. Applications using the storage pool may be temporarily unavailable, and overall performance will fall while UGOS Pro reorganizes the data.

JBOD and RAID 0 cannot be converted through this online process. RAID downgrades are also unsupported. Back up the data, create a new pool in the required mode, and restore the files.

How to Replace Every RAID Drive With Larger Drives

Use one-by-one replacement when every bay is occupied and the current pool uses RAID 1, RAID 5, RAID 6, or RAID 10.

Never remove two drives together. Complete the full disable, replacement, and repair cycle for one member before touching the next.

Replace the first drive

1. Open Storage > Hard Drive.
2. Identify the first pool member by bay number and serial number.
3. Open its menu and select Disable.
4. Review the warning and enter the administrator password if requested.
5. Wait for UGOS Pro to report that the drive is disabled.
6. Shut down the NAS.
7. Disconnect the power cable.
8. Remove the disabled drive.
9. Label it with its original bay number and set it aside.
10. Install the larger compatible drive in the same bay.
11. Reconnect power and start the NAS.

Repair the storage pool

1. Open Storage > Storage Pool & Volume.
2. Select the affected storage pool.
3. Select Repair.
4. Choose the newly installed drive.
5. Review the warning that the replacement drive will be formatted.
6. Apply the repair.
7. Monitor the progress until it reaches 100%.
8. Verify that the storage pool has returned to Normal.

Do not disable or remove the next drive while the pool is still repairing.

Repeat the cycle

Repeat the same process for every remaining member:

1. Disable one drive.
2. Shut down the NAS.
3. Replace that drive.
4. Start the NAS.
5. Repair the storage pool.
6. Wait for the pool to return to Normal.

Once every capacity-limiting member has been replaced, open Storage > Storage Pool & Volume and review the new pool capacity.

If the volume still shows its previous size, open the volume menu, select Expand, and assign the additional available capacity.

What Happens During a RAID Rebuild or Conversion?

The NAS can remain accessible during many rebuild and conversion operations, but performance will be lower. Large transfers, media indexing, backup tasks, virtual machines, containers, and other drive-heavy workloads compete with the repair process.

Pause or reduce nonessential activity until the pool returns to Normal. This shortens the degraded period and reduces stress on the surviving drives.

UGOS Pro may provide two synchronization priorities:

• RAID Sync Priority gives more storage resources to the repair or conversion.
• User Read/Write Priority preserves more performance for active users but extends the operation.

Use RAID Sync Priority when restoring redundancy quickly matters more than current file-service performance.

When Quick Repair is available, it can rebuild the portions of the pool containing data instead of processing unused capacity. This may reduce repair time and drive load, especially on a lightly used pool.

Failure tolerance also changes during the operation:

• A two-drive RAID 1 cannot tolerate another drive failure while one member is being replaced.
• RAID 5 has no tolerance for a second drive failure while the missing member is rebuilding.
• RAID 6 retains protection against one additional drive failure after one member has been removed.
• RAID 10 survival depends on whether a second failure occurs in the same mirrored pair.

A rebuilding RAID 1 or RAID 5 pool is especially vulnerable. Keep the independent backup available until the repair is complete and the restored files have been checked.

Verify the Expansion Before Resuming Normal Work

Do not treat a completed progress bar as the only test. Review the result at every layer:

1. The storage pool status is Normal.
2. Every installed drive appears in the expected bay.
3. Drive health and temperature readings are normal.
4. The storage pool reports the expected raw and usable capacity.
5. The volume has been expanded to claim the additional space.
6. Shared folders and files open correctly.
7. User and group permissions still work.
8. Containers, media applications, and virtual machines start normally.
9. Backup and synchronization tasks complete successfully.
10. A sample file can be restored from the independent backup.

Keep the removed drives untouched until the expanded pool, volume, applications, and backup jobs have all passed these checks.