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Repair Windows errors before they cause bigger problemsFix Now →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →A DAS enclosure can add storage to a NAS, but its drives do not automatically join the NAS’s existing storage pool or increase the free space on an existing volume. The outcome depends on the exact NAS and enclosure, their compatibility, the connection and operating mode, and the RAID layout. Track installed drive capacity, pool capacity, and volume capacity as separate figures.
Can I add a DAS enclosure to my NAS?
Often, but “DAS” describes storage connected directly to a host; it does not say how the NAS will present or manage the enclosure’s capacity. Check whether the supported result is a separate volume, an expansion of an existing pool, or another arrangement.
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For example, QNAP says its TR-004 can connect to a QNAP NAS over USB, but on the NAS it operates as an individual storage pool or volume that cannot be combined with the NAS’s pool. That is useful when you want separately managed storage, but it does not extend the existing pool. See QNAP’s TR-004 product details.
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A manufacturer’s expansion unit may offer a different, operating-system-managed path, but only for specified NAS models. Synology describes the RX418 as adding four SATA drive bays to compatible RackStation systems, with the drives managed in DSM; this support is not a general promise for generic USB enclosures or other NAS brands. See Synology’s RX418 page.
#1 Best Overall
- High-Speed Data Transmission: The D4-320 hard drive enclosure (a DAS, NOT a NAS) utilizes the USB 3.2 Gen2 protocol, achieving high-speed data transmission of up to 10Gbps. When equipped with four hard drives, the actual read/write speed can reach up to 1,016 MB/s (combined read/write with four SATA III HDDs of 8TB each). With just one SSD installed, the read speed effortlessly reaches 510 MB/s (SATA III 1TB SSD). The D4-320 supports a single HDD up to 30TB, with a total capacity of 120TB, and is compatible with various hard drives, including 3.5-inch SATA hard drives, 2.5-inch SATA hard drives, and 2.5-inch SATA SSDs
- Plug-and-Play Compatibility: The D4-320 USB storage supports 4 individual disks (NO RAID function), and is plug-and-play, eliminating the need for drivers. It is highly compatible with MAC, Windows, and Linux operating systems. The USB Type-C interface supports various computer interfaces, including USB 3.0, USB 3.1, USB 3.2, Thunderbolt 3, and Thunderbolt 4
- Hot Swappable Convenience: The D4-320 HDD enclosure supports hot swapping, allowing users to replace hard disks without powering off the device. This feature enhances convenience and efficiency in data transfer processes
- Tool-Free Hard Drive Management: Featuring a tool-free hard drive tray design, the D4-320 external HDD enclosure enables easy installation and removal of hard drives without requiring additional tools. Furthermore, the D4-320 incorporates TerraMaster's unique Push-lock design, automatically securing the hard drive tray upon insertion, preventing the hard drive from falling out or disconnecting
- Efficient Heat Dissipation and Quieter Operation: The D4-320 direct attached storage incorporates an intelligent temperature-controlled fan for optimal heat dissipation. Additionally, specialized sound-absorbing panels and vibration damping measures contribute to a quieter operation, with noise levels reduced by up to 50% compared to the previous generation. In standby mode, the noise level drops below 21 dB(A), creating a remarkably quiet user environment
Will a USB enclosure increase my NAS volume?
Only if the particular NAS, enclosure, connection, and supported expansion method allow it. A connected enclosure may instead appear as an independent pool or volume. Even when a pool gains capacity, an existing volume may need to be expanded separately.
Synology explains the distinction: volumes are allocated space from storage pools, and a volume can grow only when its associated pool has available capacity. Consequently, the NAS can detect new disks or show a new pool while the free space on the original volume stays unchanged. The general pool-and-volume explanation is in Synology’s storage expansion guide; exact options vary by model and configuration.
Why does my NAS show the enclosure, but my available capacity did not change?
Detection confirms that the NAS can see the enclosure; it does not establish that the enclosure has been added to the pool or volume you are monitoring. Check the storage manager for each layer separately:
Rank #2
- 【Reliable External Storage System for Individuals and business】The 3.5 hard drive enclosure supports 2.5/3.5 inches HDD and SSD, max capacity up to 20TB for each hard drive, it's a ideal external hard drive enclosure for personal or enterprise using.Save space on your desktop or laptop.
- 【No heat】The sata enclosure built in Aluminum-Alloy materials and 2 inch Fan.Maximize the security of your data.Fan noise is around 40-50 decibels, not recommended if you are very sensitive to noise.
- 【Up to 5Gbps】This dual bay enclosure equips with advanced chips and USB 3.0 output interface.Transfer 1G files in 3-5 seconds with USB 3.0 Ports, which is 10 times faster than USB 2.0.
- 【Hot Swappable Convenience】The HDD enclosure supports hot swapping, allowing users to replace hard drives without powering off the device. This feature enhances convenience and efficiency in data transfer processes.
- 【Tool-Free Installation】Featuring a tool-free hard drive tray design, the external hard drive enclosure enables easy installation and removal of hard drives without requiring additional tools. Plug and play! No fuss, no muss!
- Drives: Are the enclosure’s disks detected, and what nominal capacities and bay locations are reported?
- Pool or RAID: Did the NAS create or expand a pool, or does the enclosure expose its own pool or volume?
- Volume: Has capacity from the pool been allocated to the intended volume?
- Free space: Are you checking the free space for that same volume, rather than total installed capacity or a separate volume?
For a TR-004, QNAP documents individual-pool-or-volume behavior, so its capacity cannot be merged into the connected NAS pool. If the enclosure is a supported expansion unit instead, follow the model-specific instructions and confirm that the relevant pool and volume actually changed.
How much usable storage will I get after RAID?
Do not add the drives’ label capacities and treat the sum as usable space. RAID layout, protection overhead, system needs, enclosure behavior, and volume allocation affect the figures. The answer also depends on the drive sizes and the NAS’s supported configuration, so there is no reliable universal usable-capacity number for a DAS enclosure.
Keep these three measurements distinct:
- Installed drive capacity: the nominal capacities and number of disks physically installed.
- Pool or RAID capacity: the capacity available after the selected layout and applicable reservations.
- Volume capacity and free space: the amount allocated to a filesystem or volume, and what remains free for users and services.
Use the vendor’s RAID calculator or storage manager for an estimate based on the actual drives and configuration. Synology’s instructions for adding drives list RAID and drive requirements; available operations vary by model and drive compatibility. See Synology’s add-drives guidance.
Rank #3
- 【Reliable External Storage System for Individuals and Business】The 4 Bay Hard Drive Enclosure supports 2.5/3.5 inches HDD and SSD, max capacity up to 80TB( 20TB for each hard drive), it's a ideal external hard drive enclosure for personal or enterprise using.Save space on your desktop or laptop.
- 【No heat】The 4 bay hard drive reader built in Aluminum-Alloy materials and 2 inch Fan.Maximize the security of your data.NOTE：Fan noise is around 40-50 decibels, not recommended if you are very sensitive to noise.
- 【Up to 5Gbps】This 4 bay enclosure equips with advanced chip and USB 3.0 output interface, Max 5Gbps under UASP control.Transfer 1G movie in 3-5 seconds with USB 3.0 Ports, which is 10 times faster than USB 2.0.
- 【Wide Compatibility, Plug and Play】Equipped with USB A/C 3.0 Cable Cable.Compatible with Windows 7 and above, Mac 9.1 and above, Linux.Plug and play, no fuss, no muss.
- 【Stable power supply】Equipped with DC 12V power adapter to provide stability for high-speed transmission.
Can I use any USB drive enclosure with my NAS?
No. Physical connection alone does not guarantee compatibility, supported RAID management, drive-health monitoring, or the expansion behavior you want. Before buying, check the NAS maker’s compatibility information for the exact NAS and enclosure, including supported enclosure count and any operating-system or firmware requirements. QNAP provides a storage expansion compatibility list; other vendors may have their own model-specific resources.
Also confirm what the enclosure can do in the intended mode. QNAP describes the TR-004 as a four-bay USB enclosure and recommends connecting it directly to the host rather than through a USB hub or dock. Its product-specific limits include no RAID migration or capacity expansion, and QNAP identifies unsupported older NAS models. These statements apply to the TR-004, not to all enclosures; check QNAP’s TR-004U page and the applicable product documentation.
Should I create a separate pool or expand the existing one?
Choose based on how you intend to use and manage the added space. A separate volume can suit a distinct media library, backup target, or other data class when the NAS supports that use. It remains separate capacity: existing shares, applications, and services on another volume do not automatically gain room.
Rank #4
- Note: When using this product, please first confirm that the hard drive loaded into this product is normal, otherwise it will lead to not out of the drive, such as loading more than one hard drive, it will only show one, can not confirm which one is bad, please load a hard drive, power on, out of the drive a, confirm that it is normal, turn off, and then load the second, in the power on, out of the drive two, to confirm that it is normal, and so on, one by one to load, until you find the The problematic hard drive. For example, if there is a problem with one of the 8 hard drives, only one drive will come out.If you have any questions, please contact me promptly.
- 【Reliable External Storage System for Individuals】The 3.5 hard drive enclosure supports 2.5/3.5inches HDD and SSD , max capacity up to 160TB( 20TB for each hard driveit's a ideal external hard drive enclosure for personal or enterprise using.
- 【No heat】The 8 bay hard drive reader built in Aluminum-Alloy materials and two 2.9 inch Fans.Maximize the security of your data. NOTE：Fan noise is around 40-50 decibels, not recommended if you are very sensitive to noise.
- 【Up to 5Gbps】This 8 bay enclosure equips with advanced chips and USB 3.0 output interface, Max 5Gbps under UASP control.Transfer 1G movie in 3-5 seconds with USB 3.0 Ports, which is 10 times faster than USB 2.0.
- 【Stable power supply】Equipped with DC 12V20A power adapter to provide stability for high-speed transmission.
For expansion of an existing pool, use empty NAS bays or a vendor-supported expansion path only when the model, RAID type, and drive requirements permit it. Synology’s expansion instructions describe model-dependent options, and its pool and volume guide explains that available pool capacity and volume allocation are separate steps.
Before choosing, answer these questions:
- Will the enclosure create a separate pool or expand the existing one?
- Is the exact NAS model listed as compatible, and how many enclosures are supported?
- Which RAID modes, drive additions, or replacements are supported?
- Can the NAS monitor drive health in this setup?
- What happens to the volume if the enclosure or cable is unavailable?
- Will the volume stay within one enclosure?
For Synology DX517 deployments, Synology recommends keeping a volume physically within the NAS or within the expansion unit rather than spanning both, for better performance. That is a product-specific recommendation, not a universal rule for every NAS and expansion enclosure. See Synology’s DX517 page.
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- Before installation: Record the NAS model and software version, current pool capacity, volume capacity, and volume free space. Check the exact NAS–enclosure compatibility and the intended operating mode.
- Plan the layout: Record each proposed drive’s model and nominal capacity, the bay it will occupy, and the RAID or disk mode. Estimate usable capacity with the manufacturer’s tool rather than summing disk labels.
- Install and configure: Follow the exact enclosure and NAS instructions. Do not assume a detected enclosure has expanded an existing pool; verify whether the system created separate storage or changed a pool.
- Verify allocation: In the NAS storage manager, note the resulting pool or external-volume capacity, the capacity allocated to each volume, and the free space on the volume you intend to use.
- Update service locations: Record which shares, applications, backups, or media libraries are on the new volume so users know which capacity they are consuming.
Keep a simple inventory with one row per enclosure or volume. Include drive model, nominal capacity, bay, RAID or disk mode, pool or external-volume capacity, volume allocation, free space, and the data stored there. If dashboards report different free-space values, compare the volume and pool they monitor rather than treating the numbers as interchangeable.
Best Value
- 【Reliable External Storage System for Individuals and business】The 3.5 hard drive enclosure supports 2.5/3.5 inches HDD and SSD, max capacity up to 20TB for each hard drive, it's a ideal external hard drive enclosure for personal or enterprise using.Save space on your desktop or laptop.
- 【No heat】The sata enclosure built in Aluminum-Alloy materials and 2.7 inch Fan.Maximize the security of your data. NOTE：Fan noise is around 40-50 decibels, not recommended if you are very sensitive to noise.
- 【Up to 5Gbps】This 3.5 hard drive enclosure equips with advanced chips and USB 3.0 output interface.Transfer 1G files in 3-5 seconds with USB 3.0 Ports, which is 10 times faster than USB 2.0.
- 【Hot Swappable Convenience】The HDD enclosure supports hot swapping, allowing users to replace hard drives without powering off the device. This feature enhances convenience and efficiency in data transfer processes.
- 【Tool-Free Installation】Featuring a tool-free hard drive tray design, the external hard drive enclosure enables easy installation and removal of hard drives without requiring additional tools. Plug and play! No fuss, no muss!
Protect data before changing a live layout
There is no single safe procedure for every NAS, enclosure, RAID mode, and migration. Before moving disks, changing RAID settings, or disconnecting an enclosure, consult the exact model’s instructions and make sure you have a separate backup. RAID provides redundancy in some configurations; it is not a backup.
For the QNAP TR-004 specifically, QNAP says drive migration is limited to another TR-004. Drives moved to or from a NAS or another device will not have their files recognized, and individual mode does not support hot-swap. Do not apply those limits to a different model without checking its documentation; see QNAP’s TR-004 specifications and guidance.
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