RAID Explained for UGREEN NAS Users — RAID 1, 5 and 6 in Plain English

RAID on a UGREEN NAS protects your data against a hard drive failure. But only a hard drive failure. RAID 1, 5, and 6 are all about keeping your NAS running if one or two disks fail unexpectedly. They do nothing to protect against accidental deletion, ransomware, fire, theft, or the NAS itself failing. Understanding what RAID actually does. And what it doesn't. Is essential before you decide which level to use on your DH or DXP model.

RAID 1: Mirror Your Drives (2-Bay Models)

RAID 1 writes identical data to two drives simultaneously. If one drive fails, the other contains a complete, identical copy. The NAS continues operating without data loss and without interruption. You replace the failed drive, the NAS rebuilds the mirror, and everything continues as normal.

Storage efficiency: RAID 1 uses 50% of total raw capacity. Two 8TB drives in RAID 1 give you 8TB usable storage, with 8TB as the redundancy overhead.

Best for: 2-bay UGREEN models (DH2300, DXP2800) where RAID 5 and 6 are not possible. Also applicable as a 2-drive subset in larger arrays when maximum simplicity and reliability are the priority.

UGREEN models that support RAID 1: DH2300, DH4300 Plus, DXP2800, DXP4800, DXP4800 Plus, DXP480T, DXP6800 Pro, DXP8800 Plus. All UGREEN NAS models with 2 or more bays support RAID 1.

Fault tolerance: Survives one drive failure per mirrored pair. RAID 1 does not protect against simultaneous failure of both drives.

RAID 5: The Four-Bay Standard (3+ Drives Required)

RAID 5 distributes data and parity information across all drives in the array. If one drive fails, the NAS uses the parity data on the remaining drives to reconstruct everything that was on the failed disk. No data is lost, and the NAS continues operating in a degraded state until you replace the failed drive and rebuild the array.

Storage efficiency: RAID 5 reserves one drive's worth of capacity for parity. With four 8TB drives in RAID 5, you get 24TB usable storage (3/4 of the raw 32TB total). With three drives, you get 2/3 of raw capacity.

Best for: 4-bay UGREEN NAS models (DH4300 Plus, DXP4800, DXP4800 Plus) where balancing storage efficiency against fault tolerance is the priority. RAID 5 is the most common choice for home and SOHO NAS setups with 4 bays because it gives 75% of raw capacity while surviving any single drive failure.

UGREEN models that support RAID 5: DH4300 Plus, DXP4800, DXP4800 Plus, DXP480T, DXP6800 Pro, DXP8800 Plus. All 4-bay and larger UGREEN models. The DH2300 and DXP2800 (2-bay only) do not support RAID 5.

Fault tolerance: Survives one simultaneous drive failure. If a second drive fails before the array is fully rebuilt after the first failure, all data is lost. This is the key vulnerability of RAID 5. During a rebuild, the remaining drives are under heavy read load, which increases the probability of a second drive failure. For large drives (12TB+), rebuild times can stretch to 24-48 hours, which is a significant exposure window.

RAID 6: Dual Parity for Added Safety (4+ Drives Required)

RAID 6 extends RAID 5 by adding a second parity calculation, giving the array the ability to survive two simultaneous drive failures. This makes RAID 6 the recommended choice for 4-bay setups using large drives (8TB and above), where the rebuild window after a single failure creates a meaningful second-failure risk.

Storage efficiency: RAID 6 reserves two drives' worth of capacity for dual parity. With four 8TB drives in RAID 6, you get 16TB usable (2/4 of raw capacity). The same four drives in RAID 5 would give 24TB usable. The RAID 6 penalty is one full drive's capacity compared to RAID 5.

Best for: 4-bay or larger UGREEN NAS models using drives 8TB or larger, where the RAID 5 rebuild window creates unacceptable risk. Also the right choice for any setup where the data is difficult or impossible to replace. Family photo archives, critical business documents, or long-term archival storage.

UGREEN models that support RAID 6: DH4300 Plus (minimum 4 bays required), DXP4800, DXP4800 Plus, DXP480T, DXP6800 Pro, DXP8800 Plus.

Fault tolerance: Survives two simultaneous drive failures. The NAS continues operating and data remains accessible even with two degraded drives in the array. The array becomes unrecoverable only if a third drive fails before both failed drives are replaced and the array is fully rebuilt.

Which RAID Level for Which UGREEN Model?

The right RAID level depends on your bay count, drive sizes, and tolerance for risk during a rebuild. Here is a straightforward guide by model:

• DH2300 (2-bay): RAID 1 only. Use RAID 1 for fault tolerance, RAID 0 for maximum capacity without protection, or JBOD for independent volumes. RAID 5 and 6 require a minimum of 3 drives.
• DXP2800 (2-bay): Same as DH2300. RAID 1, RAID 0, or JBOD. RAID 5/6 not available with 2 bays.
• DH4300 Plus (4-bay): RAID 1 (2 drives mirrored), RAID 5 (3 or 4 drives), RAID 6 (4 drives), RAID 0, JBOD. For most 4-bay setups with large drives, RAID 5 or RAID 6 is the recommended starting point. Use RAID 6 with drives 8TB and larger.
• DXP4800 / DXP4800 Plus (4-bay): Same as DH4300 Plus. RAID 1, 5, 6, 0, JBOD. These Intel models also support RAID 10 (4 drives, 50% efficiency, mirrors two stripes). RAID 10 suits workloads that need faster write performance alongside redundancy.
• DXP6800 Pro (6-bay): RAID 1, 5, 6, 10, JBOD. With 6 bays, RAID 5 gives 5/6 capacity (83%); RAID 6 gives 4/6 (67%). For a 6-bay setup with large drives, RAID 6 provides a good balance of capacity and safety.
• DXP8800 Plus (8-bay): Full RAID support including RAID 10 across 8 drives. RAID 6 across 8 drives gives 6/8 (75%) usable capacity with 2-drive fault tolerance.

UGOS vs UGOS Pro: Any Difference for RAID?

Both UGOS (DH series) and UGOS Pro (DXP series) support RAID configuration via the Storage Manager interface. The setup process is functionally identical. Select your drives, choose a RAID level, and let the NAS initialise the array. There is no meaningful difference in RAID feature set between the two operating systems.

The DXP series (UGOS Pro) models with Intel CPUs do support RAID 10, which the DH series (ARM) models do not officially list. For home and SOHO use cases, RAID 5 or RAID 6 are far more common choices than RAID 10, which trades storage efficiency for write performance. A trade-off that matters more in enterprise than home environments.

One practical difference: Intel-based DXP models may complete RAID rebuild operations faster due to higher CPU throughput for parity calculations. In practice, drive speed is the limiting factor in most rebuilds, and the difference between ARM and Intel rebuild times on typical NAS drives is modest.

How to Set Up RAID in UGOS

RAID configuration on UGREEN NAS models is handled through Storage Manager in the UGOS or UGOS Pro interface.

1. Install drives: Ensure all drives are seated and recognised before configuring RAID. UGOS detects drives automatically on boot.
2. Open Storage Manager: Navigate to the Storage Manager application in the UGOS dashboard. Go to Storage Pools or RAID Groups depending on your UGOS version.
3. Create a new storage pool: Select the drives to include, choose your RAID type (RAID 1, RAID 5, or RAID 6), and confirm. UGOS will warn you that all data on the selected drives will be erased. This is the correct behaviour for a new array.
4. Initialisation: UGOS initialises the RAID array, which can take several hours for large drives. The NAS is usable during initialisation but performance will be reduced until complete.
5. Create a shared folder: Once the storage pool is ready, create shared folders (volumes) on it. These appear as network shares accessible via SMB/Samba, AFP, or other protocols.

For existing drives with data on them: RAID conversion (adding a drive to convert a JBOD to RAID 1, or expanding a RAID 5) is not always supported in UGOS without data loss. Check your specific UGOS version's documentation before attempting in-place RAID migration. The safest approach is always to back up all data first.

RAID Rebuild: What Happens After a Drive Failure

When a drive fails in a RAID 5 or RAID 6 array, the NAS enters a degraded state. It continues operating and data remains accessible, but the array is no longer protected against further failure. UGOS alerts you via the dashboard and (if configured) by email or push notification.

Steps after a drive failure:

1. Do not panic. The array is degraded but intact. Continued operation on a degraded array is normal while you source a replacement drive.
2. Source a replacement drive of equal or larger capacity. UGREEN NAS models accept a new drive of the same size or larger. Using a larger drive does not automatically increase array capacity. The new drive is treated as the same size as the smallest drive in the array.
3. Hot-swap the failed drive. UGOS supports hot-swap on all DH and DXP models. Remove the failed drive from its tray, insert the new drive, and UGOS detects it automatically.
4. Initiate rebuild. In Storage Manager, select the degraded array and choose to rebuild. UGOS rebuilds the array using the new drive, restoring full redundancy.
5. Wait for rebuild to complete. Rebuild time depends on drive size and array activity during the rebuild. Estimate approximately 8-12 hours per terabyte under normal conditions. Use the RAID Rebuild Estimator for a more precise estimate based on your drive specifications.

During rebuild, the NAS is more vulnerable than normal. Avoid running intensive tasks (large file copies, cloud sync jobs) during rebuild to reduce the probability of a second drive failure from the increased read load. If you have an active backup, verify it is current before starting the rebuild.

RAID and Backup: How They Work Together

RAID is a component of a complete data protection strategy. Not a substitute for backup. A UGREEN NAS with RAID 5 or RAID 6 protects against drive failure. It does not protect against:

• Accidental deletion: If you delete a file on a RAID 5 volume, it is gone from all drives simultaneously. RAID does not keep previous versions.
• Ransomware: Ransomware that encrypts your NAS volumes encrypts them across all RAID drives simultaneously. RAID provides no protection.
• Physical loss: Fire, flood, or theft destroys all drives in the NAS together.
• NAS controller failure: If the NAS itself fails (power surge, motherboard fault), your data may be inaccessible even though the drives are intact.

A complete data protection strategy for a UGREEN NAS follows the 3-2-1 rule: 3 copies of data, 2 on different media, 1 offsite. The RAID array is one copy. A second copy on an external USB drive or secondary NAS is the second. Cloud backup to Backblaze B2, Synology C2, or Wasabi is the offsite third. UGOS supports cloud backup to S3-compatible targets, making the offsite component straightforward to automate. See the Backup Calculator to estimate ongoing cloud storage costs for your library size in AUD.

Related reading: our NAS buyer's guide, our NAS RAID guide, and our UGREEN brand guide.

Use our free RAID Rebuild Risk Calculator to estimate the probability of data loss during a RAID rebuild.

Does the UGREEN DH4300 Plus support RAID 5?

Yes. The DH4300 Plus supports RAID 1 (2 drives), RAID 5 (3 or 4 drives), RAID 6 (4 drives), RAID 0, and JBOD. With 4 bays, you can configure RAID 5 using 3 or 4 drives, or RAID 6 using all 4 drives. RAID 6 is recommended if using drives 8TB or larger, because the longer rebuild window for large drives increases the risk of a second failure before rebuild completes.

What is the difference between RAID 5 and RAID 6 on a UGREEN NAS?

RAID 5 uses one drive for parity and can survive one simultaneous drive failure. RAID 6 uses two drives for parity and can survive two simultaneous drive failures. With four 8TB drives, RAID 5 gives 24TB usable (75% efficiency); RAID 6 gives 16TB usable (50% efficiency). RAID 6 is the safer choice for large drives because the rebuild window after a single failure is long enough that a second failure is a real risk. RAID 6 keeps your data safe through the entire rebuild process.

Can I convert from JBOD to RAID on a UGREEN NAS without losing data?

In most cases, no. UGOS RAID initialisation erases all data on the selected drives. The safest approach is always to back up all data before creating a RAID array. Some UGOS versions support online RAID migration (converting a single volume to RAID 1 by adding a second drive), but this feature availability depends on your UGOS version and model. Check the Storage Manager in your specific UGOS version before attempting in-place migration on drives containing important data.

How long does a RAID rebuild take on a UGREEN NAS?

RAID rebuild time depends primarily on drive size and array activity. For NAS-grade HDDs, a rough estimate is 8-12 hours per terabyte under normal operating conditions. A 4-drive RAID 5 array with 8TB drives (24TB usable) might take 18-30 hours to fully rebuild after a single drive replacement. Use the RAID Rebuild Estimator for a more precise estimate based on your specific drive speeds and array size.

Is RAID a backup?

No. RAID protects against a hard drive failure within the NAS. It keeps the NAS running and data accessible if one or two drives fail. It does not protect against accidental file deletion, ransomware, fire, flood, theft, or the NAS hardware itself failing. A complete data protection strategy requires separate backups, ideally following the 3-2-1 rule: three copies of your data, two on different storage media, one stored offsite or in the cloud. RAID is one layer of a broader strategy, not a substitute for it.

Does UGREEN DXP support RAID 10?

RAID 10 is supported on the DXP series (DXP4800, DXP4800 Plus, DXP6800 Pro, DXP8800 Plus) running UGOS Pro. RAID 10 combines mirroring and striping. It gives RAID 1's fault tolerance with faster write performance, but at 50% storage efficiency (same as RAID 1). RAID 10 requires a minimum of 4 drives. For most home and SOHO workloads, RAID 5 or RAID 6 are more practical choices; RAID 10's write performance advantage is most relevant for database or high-IOPS workloads.