Is RAID 5 or RAID 6 Best For You and Your NAS?

When setting up a NAS, one of the most important and long-lasting decisions you’ll make is choosing the right RAID level. This choice directly impacts how much protection you have against drive failures, how much usable storage space you retain, and how long rebuilds will take when things go wrong. Among the most debated options are RAID 5 and RAID 6, both of which use parity for data protection but differ in how much risk they can tolerate. RAID 5 offers single-drive failure protection with better capacity efficiency, while RAID 6 provides dual-drive fault tolerance at the cost of more storage overhead and longer rebuild times. It’s worth noting that although you can graduate a RAID 5 into a RAID 6 later if your needs change, this is a slow and resource-heavy process. On the other hand, RAID 6 cannot be reversed back into RAID 5, so it’s a decision that requires careful planning from the outset. The balance of speed, safety, capacity, and risk tolerance will determine which configuration is truly best for your setup.

IMPORTANT – It is essential to understand that RAID, whether RAID 5 or RAID 6, should never be considered a true backup solution. RAID protects against drive failures, but it cannot safeguard you from accidental deletion, malware, hardware faults beyond the disks, or disasters like fire and theft.

The TL;DR Short Answer – Over-Simplified, but….

• Under 8 Bays = RAID 5
• 8 Bays or Over = RAID 5, or RAID 6 with Bigger HDDs
• 12 Bays or Over = RAID 6

If you are looking for simplicity, RAID 5 will usually give you the best balance of speed, storage efficiency, and cost, but it comes with higher risk. RAID 6 is slower to rebuild, consumes more usable capacity, and involves heavier parity calculations, but it provides a much stronger safety net against drive failures. For smaller arrays with modest drive sizes, RAID 5 can be entirely sufficient, especially when paired with reliable backups. However, as drive capacities continue to grow and rebuild times stretch into days, RAID 6 becomes more attractive because it can withstand the failure of two drives without losing the array. In essence, RAID 5 is about maximizing space and performance with a moderate level of safety, while RAID 6 is about maximizing resilience and peace of mind at the expense of capacity and speed. Choosing between them comes down to how valuable your data is, how large your drives are, and how much risk you are willing to tolerate during rebuild windows.

For systems with fewer than 8 bays, RAID 5 will usually be sufficient unless you are running especially large-capacity drives or operating at a business scale where data loss cannot be tolerated. Once you reach 8 bays or higher, RAID 6 should be seriously considered, as the chances of a second drive failing during a rebuild increase along with the overall storage pool size and the scale of potential loss. At 12 bays and beyond, RAID 6 is effectively mandatory, as relying on RAID 5 at that scale means gambling with too many points of failure and too much at stake if something goes wrong.

RAID 5 vs RAID 6 – Build Time and RAID Recovery Time

The initial creation of a RAID array, sometimes called synchronization or initialization, is one of the first differences you’ll notice between RAID 5 and RAID 6. A RAID 5 setup generally completes its initial build faster because it only has to calculate and assign a single parity block across the drives. RAID 6, by contrast, has to generate and distribute two independent parity values on every stripe, which increases the workload on the system. This means that on a fresh setup, RAID 6 will take longer to complete the synchronization process before the array is fully operational, though this is usually a one-time inconvenience at the beginning of deployment. For home and small office setups, this extra build time might not matter too much, but in larger systems with many terabytes of data, it can mean several hours or even days of extra initialization work compared with RAID 5.

The difference becomes more significant when a drive fails and a rebuild is needed. In RAID 5, the system only needs to reconstruct the missing data using the surviving disks and a single parity calculation, which usually makes recovery noticeably faster. RAID 6, however, must perform double parity calculations and restore both sets of parity information onto the replacement drive, extending the recovery window. On large modern HDDs where rebuilds can take dozens of hours, or sometimes multiple days, this extra time becomes a major factor. The trade-off is that RAID 6 offers much stronger resilience while this rebuild is in progress, because the system can continue to operate and survive even if another disk fails during the process. In other words, RAID 5 rebuilds faster but carries more risk, while RAID 6 rebuilds slower but provides a crucial safety margin during the vulnerable degraded state.

Here is a recent video (using the UniFi server platform) that talks about RAID 5/6 vs RAID 10 build times and parity from 777 or 404:

RAID 5 vs RAID 6 – Protection and Vulnerability

The most important factor when comparing RAID 5 and RAID 6 is how well they protect data when drives fail. RAID 5 uses single parity, meaning the system can survive one drive failure without losing data. However, if a second drive fails during the rebuild, the entire array is lost. RAID 6 adds dual parity, which allows the system to tolerate the loss of two drives simultaneously. This extra layer of protection is especially valuable during rebuild windows, which can take many hours or days on modern high-capacity HDDs. In practice, RAID 6 dramatically reduces the risk of catastrophic data loss, at the expense of slower rebuilds and less usable capacity. A subtle but often overlooked vulnerability is the issue of batch manufacturing. Many users buy multiple drives at once, often from the same supplier, meaning the disks may come from the same production batch. If there was a hidden flaw introduced during manufacturing, it is possible that more than one disk could develop problems around the same time. With RAID 5, this creates a dangerous scenario: a second disk failure during a rebuild results in complete data loss. RAID 6 provides a safety margin against these correlated failures by protecting the array even if two drives fail close together in time. Another major risk comes from unrecoverable read errors (UREs) that can occur during rebuilds. Because every sector of every remaining drive must be read to restore the lost disk, the chance of encountering a read error rises significantly with larger drives. In RAID 5, a single URE during rebuild can corrupt the recovery process, whereas RAID 6 has an additional layer of parity to compensate, making it much more reliable during rebuilds. This is especially important in arrays of 8 or more drives, where the probability of encountering at least one problematic sector grows. For users with large arrays or very high-capacity drives, RAID 6’s extra fault tolerance is the difference between a successful rebuild and complete data loss.

RAID 5 vs RAID 6 – Capacity and Price per TB

One of the clearest differences between RAID 5 and RAID 6 lies in how much usable capacity you end up with. RAID 5 only sacrifices the equivalent of a single drive’s worth of storage to parity, which makes it the more space-efficient option. In a six-bay system with 10TB drives, RAID 5 would deliver 50TB of usable storage, while RAID 6 would only provide 40TB. That 10TB difference can be substantial when you are working with large libraries of data such as media collections, surveillance archives, or backups. For users trying to maximize every terabyte of their investment, RAID 5 makes the most efficient use of available space. However, RAID 6’s higher storage overhead translates directly into a higher effective cost per terabyte. Since two drives are always reserved for parity, the total usable space is reduced, and the price you pay for storage per TB goes up. For small home users, this may feel like wasted potential, but the trade-off is the additional layer of fault tolerance. In environments where the cost of downtime or data loss far outweighs the cost of an extra disk, RAID 6 provides stronger long-term value despite the higher price per terabyte. Ultimately, the decision comes down to whether you are more concerned with minimizing cost and maximizing space, or ensuring redundancy and peace of mind.

RAID 6 vs RAID 5 + Hot Spare Drive?

Some users prefer to run RAID 5 with a dedicated hot spare drive rather than choosing RAID 6 outright. In this setup, a single extra disk sits idle until one of the active drives fails, at which point the spare is automatically used for the rebuild. This reduces the amount of time the array spends in a degraded and vulnerable state, since the rebuild begins immediately without waiting for a replacement disk to be manually installed. While this approach still leaves you with only single-drive fault tolerance, it can feel like a middle ground between RAID 5 and RAID 6. In terms of capacity, RAID 5 with a hot spare sacrifices the same amount of usable space as RAID 6, but it does not provide the same dual-drive protection. For arrays of six to eight drives, this compromise can make sense if you prioritize capacity efficiency and faster automated recovery, but once you move into larger-scale storage systems, RAID 6 remains the safer and more resilient option.

RAID 5 vs RAID 6 – Conclusion and Verdict

When choosing between RAID 5 and RAID 6, the decision comes down to weighing efficiency against resilience. RAID 5 is faster to rebuild, provides more usable storage, and costs less per terabyte, which makes it well suited to smaller NAS setups or users who prioritize capacity and speed. RAID 6, on the other hand, offers stronger protection against drive failures, making it far more reliable for larger arrays and higher-capacity drives where rebuild times are long and risks multiply. The general consensus is that RAID 5 can still be a smart choice for arrays under eight bays, but RAID 6 becomes the clear recommendation for systems of eight drives or more, and an essential requirement at twelve drives and beyond. Above all else, it is critical to remember that RAID is not a backup. Neither RAID 5 nor RAID 6 will protect you against accidental deletion, ransomware, hardware faults beyond the disks, or disasters such as fire or theft. RAID is a safety net that improves availability, but it must always be paired with a proper backup strategy if your data truly matters.

 

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The UniFi UPS-Tower 600W UPS Review

UPDATE – The Desktop UPS TOWER is available HERE for $159 , and the 2U Rackmount UPS-2U is available later in Q4 2025 HERE for $279

UniFi’s entry into the uninterruptible power supply market brings two distinct solutions tailored for professional and prosumer environments: the UPS-Tower desktop model and the UPS-2U Rackmount unit. The tower configuration provides 1,000VA / 600W of backup capacity and uses a single 12V, 9Ah lead-acid battery, while the larger 2U rackmount version scales up to 1,440VA / 1,000W with dual battery modules. Both adopt a line-interactive architecture with simulated sine wave output, a 6–10 ms transfer time, and Ethernet-based network management. Integration is handled natively within UniFi Network, where users can adopt, monitor, and configure the UPS directly from the UniFi Controller interface. For non-UniFi deployments, both models retain NUT (Network UPS Tools) compatibility for safe shutdown and system monitoring. This marks a significant expansion of UniFi’s ecosystem into power management and continuity—areas traditionally dominated by brands like APC and CyberPower—positioning UniFi’s UPS line as a bridge between smart network infrastructure and automated power protection.

The UniFi UPS-Tower 1000VA / 600W Review – Quick Conclusion

The UniFi UPS-Tower and UPS-2U deliver practical and ecosystem-focused power protection for small network environments. Both models emphasize integration and manageability rather than raw performance, providing stable 120V line-interactive backup power with simulated sine wave output. The tower model offers 600W of protection in a compact desktop enclosure, while the rackmount unit increases capacity to 1,000W with dual batteries. Integration through the UniFi Network Controller is straightforward, enabling central monitoring and alerting without external software. While limitations such as the lack of USB ports, PoE passthrough, and pure sine wave output restrict versatility outside the UniFi ecosystem, both units are solid entries for users seeking consistent, centrally managed backup power within UniFi-managed infrastructures.

The UniFi UPS-Tower UPS Review – Design & Connectivity

The UniFi UPS-Tower adopts a vertically oriented, compact chassis that measures 288 x 99 x 280.5 mm and weighs just over 8 kg. Its enclosure is built from a polycarbonate and ABS blend, which offers a balance between durability and low weight, and the overall shape resembles a small desktop speaker or heater.

The unit’s IP20 rating indicates it is intended for indoor use only, with ventilation panels positioned at the top, sides, and bottom to maintain airflow. During testing, internal temperatures averaged around 45–47°C after 24 hours of continuous operation, demonstrating stable thermal management for a unit of this density. The design is understated, with no LCD screen or physical display, relying instead on LED indicators and the UniFi interface for monitoring battery level and status.

In terms of connectivity, UniFi has implemented a clear division between power protection and control interfaces. On the rear panel, the UPS-Tower provides five surge-only outlets and five battery-backed surge-protected outlets, all of which are NEMA 5-15R ports suitable for 120V environments. The input connection uses a NEMA 5-15P plug, rated for 12A maximum load, supporting both 50 and 60 Hz operation. While this configuration is typical of compact line-interactive UPS units, the number of protected outlets is unusually high for its size, making it suitable for powering multiple small network devices, NAS units, or edge appliances simultaneously. However, only the five battery-backed ports will remain operational during a power loss.

UniFi has also included Ethernet management for remote monitoring and control. The rear I/O layout features a 100/10 MbE network connection that links the UPS directly into the UniFi ecosystem, as well as two GbE ports for surge in/out, allowing for protection of wired data paths. This implementation enables the UPS to send automatic notifications and power-state updates to the UniFi controller, ensuring that connected devices can safely power down when mains supply is interrupted. While users will not find USB connectivity here—a feature absent from both models—Ethernet management ensures seamless network-level integration with UniFi OS devices and provides remote monitoring capabilities not typically available in basic desktop UPS designs.

On the visual and operational interface side, UniFi relies on a multi-stage LED system to communicate battery and status information. A ring of LEDs on the front panel indicates power state, network connectivity, and battery percentage, with specific color patterns representing states such as initialization, adoption, or firmware upgrades. For example, a steady blue LED denotes normal operation, while flashing red signals a low battery, and alternating white/blue indicates firmware updating. This LED-centric approach aligns with UniFi’s existing product language and keeps the design minimalistic while relying on software integration for detailed telemetry.

Physically, the UPS-Tower fits neatly into a small office or studio environment, blending alongside UniFi routers or switches without dominating desk space. It operates quietly, with only a faint hum from the internal fan during battery mode. The 2U rackmount model, by contrast, uses a galvanized steel enclosure with front ventilation and nearly double the weight at 14 kg, prioritizing durability for data racks and wiring cabinets.

Both maintain an IP20 protection rating, ensuring basic safety against accidental contact but not dust or moisture resistance. Overall, UniFi’s approach emphasizes modularity, network integration, and compactness over display-driven functionality, positioning these UPS units as discreet but essential components within managed network setups.

The UniFi UPS-Tower UPS Review – Internal Hardware

Internally, the UniFi UPS-Tower follows a line-interactive architecture, combining voltage regulation with battery backup to ensure smooth transitions during power interruptions. The system utilizes an automatic voltage regulation (AVR) circuit that adjusts minor fluctuations in mains voltage without switching to battery mode, minimizing wear on the internal power cells. In the event of an outage or severe voltage dip, the UPS switches to battery operation within 6 to 10 milliseconds, maintaining output stability at 120V AC with a ±10% regulation margin. The waveform produced in battery mode is a simulated sine wave, which is adequate for most networking gear and consumer electronics, though not ideal for high-sensitivity audio, medical, or laboratory equipment. Power delivery remains consistent throughout short outages, allowing network hardware, NAS units, and servers to complete safe shutdown procedures.

The UPS-Tower contains a single 12V, 9Ah sealed lead-acid battery, user-removable via a bottom access panel. This design makes future maintenance straightforward, allowing owners to replace the battery when its capacity diminishes after several years of use. At full load (600W), the runtime averages around 2 minutes, while at half load, it extends to approximately 7 minutes before automatic shutdown. Recharge time to 90% capacity is listed at 6 to 8 hours. Thermal performance under sustained use is stable, and the inclusion of passive and active ventilation ensures no overheating under normal operating conditions. The system is also protected against short circuits, overloads, and over-voltage faults, automatically tripping into fault mode if thresholds of 110% to 120% load are exceeded.

Comparatively, the UPS-2U Rackmount uses a dual-battery setup with two 12V, 9Ah lead-acid modules to achieve 1,440VA / 1,000W output capacity. It shares the same waveform and transfer time but provides slightly extended runtime—2.3 minutes at full load and 8 minutes at half load—thanks to the added battery reserve. It also benefits from a galvanized steel chassis that enhances durability and is better suited for professional rack environments. Both systems are NDAA-compliant and certified under FCC, IC, UL 1778, and CSA C22.2 No. 107.3, ensuring safety and performance standards for commercial and residential use. In both models, system management and network telemetry are handled by a dedicated network controller chip, enabling UniFi OS integration and data synchronization with other UniFi devices.

The UniFi UPS-Tower UPS Review – Functionality

The UniFi UPS series is built around simplicity and ecosystem-level integration rather than feature-heavy configuration. Both the UPS-Tower and UPS-2U connect directly to the UniFi Network controller via Ethernet, where they appear alongside other UniFi devices for adoption. Once added, users can view real-time battery percentage, load level, input/output voltage, and system temperature directly from the UniFi interface. The units are also capable of sending power event notifications when mains power fails or returns, ensuring administrators receive alerts through the existing UniFi management system without relying on third-party monitoring software. This network-level approach allows the UPS to act as both a power backup and an automated coordination point for controlled shutdowns across UniFi infrastructure, such as Dream Machines, switches, or NAS units.

Integration with non-UniFi devices is handled through Network UPS Tools (NUT) compatibility. This makes the UPS-Tower particularly flexible in mixed environments where NAS devices or servers from other vendors, such as Synology or QNAP, require graceful shutdown when the UPS switches to battery mode. Users can define credentials and associate the UPS with NUT clients on the same network to relay status and trigger automated shutdowns once the battery reaches a predefined threshold. Although the review highlighted the lack of USB connectivity, which restricts plug-and-play use with devices expecting a traditional USB UPS handshake, the Ethernet management layer compensates by offering wider network-based communication. However, features such as per-device runtime configuration or selective port control are not yet implemented, leaving shutdown scheduling dependent on firmware updates or future model revisions.

The control and monitoring interface remains minimalistic, relying heavily on UniFi’s centralized GUI rather than onboard interaction. LEDs on the chassis provide a clear visual indication of status—covering power mode, adoption state, and battery level—but all deeper telemetry must be accessed through UniFi Network. Once paired, users can also configure email or push notifications for voltage irregularities, battery health alerts, and firmware updates. It is important to note that the current firmware does not support pure sine wave operation or lithium-ion battery upgrades, though UniFi has stated that future models will expand the portfolio to include these higher-end options. In its present form, the UPS-Tower and UPS-2U focus on stability, ease of deployment, and unified management within a single software environment, making them efficient for UniFi users seeking automation without added complexity.

The UniFi UPS-Tower UPS Review – Conclusion and Verdict

The UniFi UPS-Tower and UPS-2U represent the brand’s first foray into managed backup power systems, designed primarily to extend the reliability and consistency of the broader UniFi ecosystem. Both units share the same line-interactive architecture, simulated sine wave output, and Ethernet-based monitoring, offering a predictable and easily managed experience for users already invested in UniFi infrastructure. Their minimalist design, compact footprint, and seamless adoption through the UniFi Network Controller make them suitable for environments where simplicity, remote monitoring, and integration outweigh the need for advanced runtime management or pure sine wave output. For most small network or NAS setups, either model will provide adequate protection during short outages and brownouts, while ensuring systems are safely powered down when battery capacity is depleted.

However, their appeal remains closely tied to the UniFi ecosystem. The absence of USB connectivity, PoE passthrough, and lithium-ion battery options limits their usefulness in heterogeneous or high-performance environments. Users seeking pure sine wave support, longer runtimes, or advanced per-device control will likely need to wait for the next generation of UniFi UPS models, which the company has already suggested will expand to include these options. As they stand, the UPS-Tower and UPS-2U are well-built, tightly integrated, and cost-effective for UniFi users, but less compelling for those operating outside that ecosystem. They function precisely as intended: reliable, network-aware power backups for UniFi-managed systems, providing foundational stability rather than feature innovation.

UniFi UPS-Tower PROS

UniFi UPS-Tower CONS

Seamless integration with UniFi Network Controller for centralized management Compact and minimalistic design with low noise and stable thermal performance Ethernet-based control and monitoring eliminate the need for USB connectivity NUT compatibility enables basic third-party system integration User-replaceable lead-acid battery for extended product lifespan Competitive pricing relative to similar managed UPS devices Reliable short-term backup and safe shutdown coordination for UniFi devices

No USB port for direct communication with standalone servers or NAS systems Simulated sine wave output limits use with sensitive equipment Lacks PoE passthrough and per-device power control options

 

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This description contains links to Amazon. These links will take you to some of the products mentioned in today's content. As an Amazon Associate, I earn from qualifying purchases. Visit the NASCompares Deal Finder to find the best place to buy this device in your region, based on Service, Support and Reputation - Just Search for your NAS Drive in the Box Below

Need Advice on Data Storage from an Expert?

Finally, for free advice about your setup, just leave a message in the comments below here at NASCompares.com and we will get back to you. Need Help? Where possible (and where appropriate) please provide as much information about your requirements, as then I can arrange the best answer and solution to your needs. Do not worry about your e-mail address being required, it will NOT be used in a mailing list and will NOT be used in any way other than to respond to your enquiry. [contact-form-7] TRY CHAT Terms and Conditions   Alternatively, why not ask me on the ASK NASCompares forum, by clicking the button below. This is a community hub that serves as a place that I can answer your question, chew the fat, share new release information and even get corrections posted. I will always get around to answering ALL queries, but as a one-man operation, I cannot promise speed! So by sharing your query in the ASK NASCompares section below, you can get a better range of solutions and suggestions, alongside my own.

WE LOVE COFFEE