USB 3.0 / eSATA Dual-Bay Trayless 3.5” SATA III Hard Drive Enclosure with UASP - 2-Bay SATA 6 Gbps Hot-Swap HDD Enclosure

Connect two hot-swappable 3.5" SATA III hard drives to your computer externally through USB 3.0 with UASP or eSATA

Product ID: S352BU33RER

3 stars (5 reviews) |
  • Supports SATA III (6 Gbps) and UASP (5 Gbps) for optimal performance
  • Hardware RAID with support for RAID0 / RAID1 / BIG / JBOD
  • Trayless removable HDD slots with drive locks
Your price
$4,148.15 MXN
VAT included in the price

The S352BU33RER 2-Bay RAID enclosure lets you build an external RAID array with two 3.5” SATA hard drives, and connect to your computer through USB 3.0 or eSATA.

For fast performance and efficient data transfers, the enclosure supports SATA III transfer speeds -- up to 6 Gbps when connected through eSATA. The versatile RAID enclosure can also be connected through USB 3.0, with support for UASP, performing up to 70% faster than conventional USB 3.0 when paired with a UASP-enabled host controller. See our UASP testing results below for further details.

The external RAID enclosure features a hardware RAID controller, supporting JBOD, Spanning, RAID 0, and RAID 1 -- to achieve greater drive capacity, or secure data redundancy. The RAID controller is also front mounted for ease of access when changing your RAID mode.

For fast and easy drive installation and removal, the dual drive enclosure features a convenient trayless system that eliminates having to mount and fasten your drives, saving time and hassle.

To ensure compatibility with your computer system, the S352BU33RER supports all of the leading operating systems, including: Microsoft Windows® (8/7/Vista/XP/Server 2008/Server 2003), Apple® OSX (10.9/10.8/10.7/10.6), Linux, and Google Chrome OS™.

The S352BU33RER is backed by a 2-year warranty and free lifetime technical support.

Improved Performance with UASP

UASP is supported in Windows 8, Mac OSX (10.8 or above), and Linux. In testing, UASP performs with a 70% faster read speed and 40% faster write speed over traditional USB 3.0 at peak performance.

UASP Speed Diagram

At the same peak in testing UASP also shows an 80% reduction in required processor resources.

UASP Speed Diagram

Testing results were obtained using an Intel® Ivy Bridge system, a UASP-enabled Enclosure, and a SATA III solid state drive.


  • Build an external RAID 1 array for data redundancy, to protect against drive failure when working with important data
  • Externally work with very large files securely in video editing or photography applications
  • Quickly transfer large data files from your computer to a secure external RAID enclosure

The Advantage

  • Versatile connectivity options, through either USB or eSATA
  • Maximize performance, with file transfer speeds up to 6Gbps using eSATA
  • Achieve greater drive capacity or secure data redundancy with a built-in hardware RAID controller

Partner Numbers

  • Ingram Mexico A84011X
  • UPC 065030858175


  • OS Independent logo
OS independent; No software or drivers required


Warranty Information Warranty 2 Years
Connector(s) 2 - Drive Connectors SATA Data & Power Combo (7+15 pin)
1 - Host Connectors USB Type-B (9 pin) USB 3.0
eSATA (7 pin, Data)
Environmental Operating Temperature 5°C to 35°C (41°F to 95°F)
Storage Temperature -20°C to 50°C (-4°F to 122°F)
Humidity 20%RH~80%RH
Hardware Interface USB 3.0 & eSATA
Bus Type USB 3.0
Front Door Key Lock Yes
Number of Drives 2
Drive Size 3.5in
Compatible Drive Types SATA
Drive Installation Removable
Number of internal 3.5 inch bays 2
Fan(s) Yes
1 - Fans 70 mm
Fan Bearing Type Sleeve Bearing
Chipset ID JMicron - JMS562
Indicators 1 - LED Indicators HDD 1 Activity
HDD 2 Activity
Packaging Information Package Height 7,4 in [18,7 cm]
Package Length 11,9 in [30,1 cm]
Package Width 8,2 in [20,8 cm]
Shipping (Package) Weight 6,3 lb [2,9 kg]
Performance Maximum Data Transfer Rate 6 Gbps
Type and Rate USB 3.0 - 5 Gbit/s
UASP Support Yes
4Kn Support No
Type and Rate SATA III (6 Gbps)
Port Multiplier Yes
Hardware Raid Supported Yes
Supported RAID Modes BIG (Spanning or Concatenation)
JBOD - (Just a Bunch of Disks)
RAID 0 (Striped Disks)
RAID 1 (Mirrored Disks)
Max Drive Capacity Currently tested with up to 4TB 7200 RPM 3.5" hard drives per bay (8TB total) and 2TB 5900 RPM 2.5" hard drives (2TB total)
Hot Swap Capability Yes
Air Flow Rate 12.72 CFM
Noise Level 26.24 dBa
Physical Characteristics Color Black
Product Length 8,5 in [21,5 cm]
Product Width 5,1 in [13 cm]
Product Height 4,6 in [11,8 cm]
Weight of Product 4,1 lb [1,8 kg]
Power Power Source AC Adapter Included
Input Voltage 100 - 240 AC
Output Voltage 12V DC
Output Current 3 A
Power Consumption (In Watts) 36
Software OS Compatibility OS independent; No software or drivers required
What's in the Box 1 - Included in Package USB 3.0/eSATA Dual 3.5" SATA HDD Trayless Enclosure
eSATA Cable
USB 3.0 Cable
Universal Power Adapter (NA/UK/EU)
Instruction manual
2 - Included in Package Drive Bay Keys


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We are always ready to assist you with any questions you may have.

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Frequently Asked Questions


SATA hard drive controllers require a feature called port multiplier to read more than one hard drive per SATA or eSATA port. The port multiplier feature is not standard on many SATA hard drive controllers.

If your computer is only recognizing one of your hard drives, you need to plug the eSATA cable into a SATA controller that includes the port multiplier feature. If none of your current hard drive controllers include this feature, you can add a hard drive controller that does support port multiplier in any available expansion slot (for example, PCI, PCI-Express, PCMCIA, CardBus, or ExpressCard). has hard drive controllers available that support the port multiplier feature. To view the hard drive controllers, click here:

If you have a hard drive controller card that does support the port multiplier feature but it is only reading one hard drive at a time, update the drivers of the hard drive controller. To find the most current drivers, click here:

When you troubleshoot issues with a hard drive enclosure, there are some quick tests that you can complete to rule out potential problems. You can test to make sure that the following components are working correctly and are not the source of the issue:

  • Cables
  • Hard drives
  • Hard drive enclosure

To test your setup components, try the following:

  • Use the cables, hard drives, and hard drive enclosure in another setup to see if the problem is with the components or the setup.
  • Use a different cable, hard drive, and hard drive enclosure in your setup to see if the problem persists. Ideally, you should test a component that you know works in another setup.

When you test the hard drive and hard drive enclosure, it is recommended that you do the following:

  • To check Disk Management, press the Windows key + R, type diskmgmt.msc, and press Enter. Check to see if your hard drive is listed.
  • If the hard drive is listed with unallocated space, the hard drive needs to be reformatted. Right-click unallocated and click New Simple Volume. Follow the on-screen instructions to complete the reformatting.​

Note: Formatting a hard drive erases all of the data on it. Make sure that you back up all of your data before you reformat the hard drive.​

  • If the hard drive is listed as healthy but does not have a drive letter, for example, C:, right-click healthy and click Change Drive Letter and Paths. Click Add, assign a drive letter, and click OK.

Note: A formatted hard drive will not show up in Computer or My Computer until it has a drive letter assigned to it.

In order to rebuild a RAID array, you need to replace a physical drive with an identical drive on the same RAID controller. Although standard RAID levels are generally agreed upon throughout the industry, the implementation varies between manufacturers. RAID arrays are typically not accessible when they are moved to another controller, and data may be unrecoverable if the drives are out of order or have been formatted or accessed by another RAID controller.

If a RAID controller has failed, you should get the exact same model of RAID controller.  

Note: If a drive or drives were damaged, it is possible that the RAID array may be permanently unrecoverable.

RAID should not be considered a replacement for backing up your data. If critical data is going onto a RAID array, you should back up the data on another physical drive or logical set of drives.

Rebuild a RAID array

With the following RAID modes, recovery is possible using the same product. Refer to the following table for the appropriate method to use to recover your RAID array.

RAID mode Max # of failed drives Procedure
RAID 1 Only one drive is needed for recovery.
  1. Determine which drive is operational by using the RAID management utility (if available) or test each drive individually on a different hard drive controller (for example, a hard drive docking station or SATA controller).

  2. Replace the failed drive with an identical hard drive.

The array will rebuild and is accessible during the rebuilding process.

RAID 3 Single drive failure will rebuild.
  1. Determine which drive is defective by using the RAID management utility (if available) or with diagnosis LEDs on the controller or enclosure.

  2. Replace with an identical hard drive.

Note: Do not change the order of the drives.

  1. The array may be accessible during the rebuild, but you should let the controller rebuild without interruption so that performance is not compromised.

RAID 5 Single drive failure will rebuild.
  1. Determine which drive is defective by using the RAID management utility (if available) or with diagnosis LEDs on the controller or enclosure.

  2. Replace with an identical hard drive.

Note: Do not change the order of the drives.

  1. The array may be accessible during the rebuild, but you should let the controller rebuild without interruption so that performance is not compromised.

RAID 10 Only one drive in a mirrored set can fail.
  1. Determine which drive is defective by using the RAID management utility (if available) or with diagnosis LEDs on the controller or enclosure.

  2. Replace with an identical hard drive.

Note: Do not change the order of the drives.

  1. The array may be accessible during the rebuild, but you should let the controller rebuild without interruption so that performance is not compromised.


How To

To confirm that the Mac OS detects your USB device, complete the following:

  1. Click the Apple icon.
  2. Click About This Mac.
  3. Click More Info or System Report.
  4. Under the appropriate heading, confirm that your USB device is listed and that there isn't an error. For example, a network card would be under Ethernet Cards.

You may need to refresh the System Information page after you plug in your device.  To do so, press Command R with the System Information page open.

Your USB device is listed according to the name of the chipset. To determine the name of the chipset of your USB device, navigate to and look on the Technical Specifications tab for your product.

Before You Buy

To determine if your hard drive will work in this enclosure, on the product page, click the Technical Specifications tab, and do the following:

  • Make sure that the enclosure supports the storage size of your hard drive. If the storage size of your hard drive is larger than what the enclosure was tested with, the hard drive will likely still work with the enclosure.
  • Confirm that your hard drive uses the same interface type as the enclosure. For example, IDE, SATA, or M.2.
  • Make sure that the enclosure supports the physical size of your hard drive, such as 2.5 inches or 3.5 inches.
  • Make sure that the enclosure supports the height of your hard drive. For example, 9 mm or 15 mm.
  • Verify that the power consumption of your hard drive doesn’t exceed the power output of the enclosure. If you’re using multiple hard drives, make sure that the combined power consumption of all of the hard drives doesn’t exceed the power output of the enclosure.

Note: Not all devices support each of the RAID modes described below. For more information on the RAID modes that your device supports, refer to the manual or the product page.

Redundant Array of Independent Disks (RAID) is a virtual disk technology that combines multiple physical drives into one unit. RAID can create redundancy, improve performance, or do both.

RAID should not be considered a replacement for backing up your data. If critical data is going onto a RAID array, it should be backed up to another physical drive or logical set of drives.

The following are terms that are normally used in connection with RAID:

  • Striping: data is split between multiple disks.
  • Mirroring: data is mirrored between multiple disks.
  • Parity: also referred to as a checksum. Parity is a calculated value used to mathematically rebuild data.

Different RAID levels exist for different application requirements.

Refer to the following table for the list of RAID modes offered by some products:

RAID mode Description Operation Advantages Disadvantages Recovery
RAID 0 Striped disks Data is split evenly between two or more disks. Large size and the fastest speed. No redundancy. If one or more drives fails, this results in array failure.
RAID 1 Mirrored disks Two or more drives have identical data on them. A single drive failure will not result in data loss. Speed and size is limited by the slowest and smallest disk. Only one drive is needed for recovery.
RAID 3 Striped set with dedicated parity Data is split evenly between two or more disks, plus a dedicated drive for parity storage. High speeds for sequential read/write operations. Poor performance for multiple simultaneous instructions. A single drive failure will rebuild.
RAID 5 Striped disks with distributed parity Data is split evenly between three or more disks. Parity is split between disks. Large size, fast speed, and redundancy. The total array size is reduced by parity. A single drive failure will rebuild.
RAID 10 1+0; Striped set of Mirrored Subset Four or more drives are made into two mirrors that are striped. Larger size and higher speed than RAID-1, and more redundancy than RAID-0. No parity. Only one drive in a mirrored set can fail.
JBOD Just a Bunch Of Disks Any number of drives are accessed independently by the operating system. Software RAID modes can be used. Hardware RAID may have better performance. N/A
Big Spanning or Concatenation Data is written on one drive until it is full, and then the next drive(s) until it or they are full. Creates a very large and simple array.

No redundancy.

Clone RAID 1 + Spare

Two drives have identical data, plus one drive is used for rebuilding in case of a primary array failure.

Seamless operation when one drive fails in a RAID-1 array. Spare drive is not accessible to the user. Only one drive is needed for recovery.


Hard Drives

Windows 10 

Before you can access a new or formatted drive in your operating system, you need to initialize it first and then create a partition on the drive. A partition defines an area of the drive to use for storing data. The partition uses a file system (for example, ex-FAT, NTFS, and so on).

Initialize a drive

Note: You typically only need to initialize a drive if the drive is new. If you cannot find an uninitialized drive in Disk Management, skip the following steps and try to partition your device.

  1. Press the Windows key + R, type compmgmt.msc, and click Run to open Computer Management.

  2. Navigate to Disk Management.

  3. When prompted to, initialize your disk(s). If you are running Windows® 7 or later and are using a drive larger than 2TB, initialize the disk(s) with GPT. If you are running an earlier version of Windows, initialize the disk(s) with MBR. For more information, visit the following FAQ:

  4. Click OK.

Create a partition in a drive

Note: The following steps create an NTFS partition that uses the entire drive space. To use a different file system, select a different option in step 6.

  1. Right-click Unallocated or RAW volume, and select New Simple Volume.

  2. In the New Partition Wizard, click Next.

  3. Select Primary partition.

  4. Leave the partition size set to default, and click Next.

  5. Assign a drive letter or leave it set to the default, and click Next.

  6. Enter the following settings to format the partition:

  • In the File System field, enter NTFS.
  • Set the Allocation unit size to Default.
  • In the Volume label field, enter <your name/reference>.
  • Select the Perform a quick format check box.
  • Clear the Enable file and folder compression check box.
  1. Click Next > Finish.

The new drive should appear in Windows Explorer.

Mac OS

Before you can access a new or formatted drive in your operating system, you need to initialize it first and then create a partition on the drive. A partition defines an area of the drive to use for storing data. The partition uses a file system (for example, HFS+, ex-FAT, NTFS, and so on).

Initialize a drive

Mac OSX detects a drive that needs to be initialized and automatically prompts you to initialize the drive. If you are prompted to initialize the drive, click Initialize. If you are not prompted to initialize the drive and you cannot find the drive in Finder, you will need to create a partition on the drive.

Create a partition on a drive

Note: The following steps create an HFS+ (Mac OS Extended (Journaled)) partition that uses the entire drive space.

To create a partition on a new drive, complete the following:

  1. Open Finder.

  2. Navigate to Applications and click Utilities.

  3. Open Disk Utility.

  4. Select the new drive and click the Partition tab.

  5. Click Options and verify that it is set to GUID Partition Table.

  6. Enter a name for the partition.

  7. Click Partition.

The drive should now be accessible in Finder.

For products related to this article, click here.

Compliance and safety

Compliance letters

Safety Measures

  • If product has an exposed circuit board, do not touch the product under power.
  • If Class 1 Laser Product. Laser radiation is present when the system is open.
  • Wiring terminations should not be made with the product and/or electric lines under power.
  • Product installation and/or mounting should be completed by a certified professional as per the local safety and building code guidelines.
  • Cables (including power and charging cables) should be placed and routed to avoid creating electric, tripping or safety hazards.
*Product appearance and specifications are subject to change without notice.

Customer Reviews

(5 reviews)
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1 - 5 of 5 Reviews
(4 Stars)

Works good with some tweaking.

By: Locotin - 02/01/2017
I had it for 4 months. I wanted a Raid0 for my games. Tried the 3.0. USB cable and it initialized great but I lost my raid after a couple of days. Also, I had to connect and disconnect everytime my laptop when to sleep or idle for too long. I tried disabling all USB sleep times and nothing. I kept losing my Raid0 after a while. Then I got a brainstorm and decided to use the eSATA to USB that I bought with it which I did not think I need it. I connected the eSATA side to the enclosure and the USB directly to the laptop bypassing all HUBS. WORKED GREAT. It has been three months now and my Raid0 is intact half way full with games and works super fast and my games have no lag whatsoever. the only thing I dont like is this humming sound it makes when it turning on or off. It makes me feel like is about to fail. Is not my drives is the enclosure making that weird, old sound humming. Other that that, it has been working great with the eSATA to USB cable.
| Helpful?
(2 Stars)

rigid case but has areas for improvement

By: doomi - 12/27/2018
after around a year or two of constant work as a server raid datastorage the fan stopped working. Replacing it is possible but plug is a bit hard to reach. The documentation, especially for the LED signals should be dramatically improved - some forums are better information sources than the official manual. Something I am currently struggling with and I can't find any info about, is if this enclosure is compatible with 4Kn drives - I have put two 6TB 4Kn (HGST) drives in now and did some tries but do not have the feeling it works (attached via eSATA or USB to a Ryzen 7 system on win10). One LED is constant blue, one LED is constant purple (=red) for over half an hour now and the PC doesn't detect anything. At some point the discs also slow down. Same situation with only 1 drive plugged in. The HDDs themselves are new and both ok and detected fine when directly attached to the internal SATA ports of the PC. The controller is a JMicron - JMS562 which (bad) documentation is also not mentioning 4Kn support, only Win8 compatibility is assured which would speak pro 4Kn, but I fear this is not the case. The enclosure itself is rigid and easy to use. the eSATA cable could be fixed a bit better, but it's ok. the probably missing 4Kn support and the bad LED documentation as well as the broken fan however make me rate it with 2-3 stars max. Oh, and I also lost the raid 1 one or two times with the old disks and was glad I had some backups...
| Helpful?
Brian, Customer Support on 1/2/2019 1:02:57 PM
Thanks for sharing your feedback. We really apologize for the confusion about the LEDs and 4Kn drive support. We'd be happy to replace the fan if the product is within the 2 year warranty period. Regarding the LED behavior, during normal operation each drive LED will be solid blue. When there is drive activity a red LED will also flash making it appear purple. When the Rebuild light is on the array has encountered an error. The rebuild light will flash while the array is rebuilding. During the rebuild process both drive activity lights will flicker frequently appearing purple. We'll update our online manual to include this information. Unfortunately this model does not function with 4Kn drives. We recommend our S352BU313R if you require a 2 bay enclosure with RAID functionality and the ability to use 4Kn drives.
(3 Stars)

Awesome Minus Cheap Fan

By: CPUaffinity - 01/03/2020
This enclosure has been solid for quite some time. Probably just outside of the warranty period. Everything was great until the fan started making noise randomly. It is not easy to replace unless you have tiny hands.
| Helpful?
Matt, Customer Support on 1/31/2020 2:46:54 PM
We're sorry to hear about the issues that you're experiencing with the fan on our S352BU33RER. We would like to speak with you about this problem as the fan should not be making any random noises. Please feel free to contact us at and reference this review so that we can help fix this for you. Our Technical Advisors are available 24 hours a day, 5 days a week to provide assistance.
(5 Stars)

Works with 16TB!!!! Yay!

By: Gordward - 05/17/2021
I had 2 spare 16TB Iron Wolf Drives and needed a RAID 1 enclosure. This one did not advertise a 16TB compatibility. But, after hooking directly to the USB 3.0 Port (no hub) and letting the RAID Mode finish it's config, the Device showed up and away I went into Backup Heaven!
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(1 Stars)

Promising but a failure.

By: Quin - 06/10/2021
I bought this to use for backup of my PC. First oddity I noticed is that if you turn it on and the USB cable isn't plugged into a computer, the unit will shut off within a couple seconds. This seems rough on the hard drives. I tried "stripping" mode to combine two disks so I could get more storage space. Within a day, the "rebuild" LED turned on (even after redoing the setup process a few times) and the volume was inaccessible. This was unreliable so I decided to use the device differently. I decided to use it to copy some important data off of a couple drives at the same time (in "standard" mode). These were different drives (6 TB and 2 TB) that I had for a couple years to store important data. I copied from these drives off and on over a few days; it worked well. Then, Windows 10 decided to reboot for an update (I thought I disabled this!). When it came back on, 6 TB total of data was lost. "The file system is corrupt". This was my first and last experience with StarTech. What a depressing failure. 8 TB of data, GONE! Thanks.
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