Sabrent Rocket XTRM-Q USB / Thunderbolt 3 Dual Mode External SSD Review: Yin and Yang

The external storage market has shown renewed vigor in recent years, thanks in part to growth fueled by bus-powered flash-based storage solutions. The introduction of 3D NAND, coupled with the increasing confidence of manufacturers in QLC (4-bits per cell) has brought down the cost of these drives to the point where even a reasonably spacious external SSD can be had for an equally reasonable price. And though this means that NAND manufacturers like Western Digital, Samsung, and Crucial/Micron have an inherent advantage in terms of vertical integration, the availability of cheap flash in the open market has also enabled other vendors to come up with innovative solutions.

Today, we're looking at a unique product in the external SSD market – the Sabrent Rocket XTRM-Q. A true dual-mode Thunderbolt 3/USB drive, the Rocket XTRM-Q can be natively used with both Thunderbolt 3 and USB hosts. This means that it can deliver speeds over 2GBps on a Thunderbolt 3 connection, or fall back to USB mode and still deliver 1GBps or more with a USB 3.2 Gen 2 connection. Compared to most external SSDs on the market, which are virtually always USB-only or Thunderbolt-only, this allows Sabrent's drive to offer USB-style universal compatibility while still making the most of the host it's connected to, using USB when it's available, or upgrading to Thunderbolt as appropriate to let the drive run as fast as it can.

Meanwhile, not unlike their efforts with internal (M.2) products, Sabrent is also at the leading-edge of storage capacity with the Rocket XTRM-Q, offering versions of the drive with up to 8TB of storage. Overall, the Rocket XTRM-Q is available in capacities ranging from 500GB up to 8TB, with Sabrent using QLC NAND across the family to hit their price and capacity goals.

For this review we're looking at two of the mid-tier Rocket XTRM-Q models – the 2TB and 4TB models – in order to size up the performance of the drives and see how they stack up against the other products in the market.

Introduction and Platform Analysis

External bus-powered storage devices have grown both in storage capacity as well as speeds over the last decade. Thanks to rapid advancements in flash technology (including the advent of 3D NAND and NVMe) as well as faster host interfaces (such as Thunderbolt 3 and USB 3.2 Gen 2x2), we now have palm-sized flash-based storage devices capable of delivering 2GBps+ speeds. Depending on the performance profile and the components used, these flash drives fall into one of six categories:

• 2.5GBps+ class: Thunderbolt SSDs with PCIe 3.0 x4 NVMe drives
• 2GBps+ class: USB 3.2 Gen 2x2 SSDs with PCIe 3.0 x4 NVMe drives
• 1GBps+ class: USB 3.2 Gen 2 SSDs with PCIe 3.0 (x4 or x2) NVMe drives
• 500MBps+ class: USB 3.2 Gen 2 SSDs with SATA drives
• 400MBps+ class: USB 3.2 Gen 1 SSDs with SATA drives
• Sub-400MBps+ class: USB 3.2 Gen 1 flash drives with direct flash-to-USB controllers

Almost all external SSDs currently in the market can slot into one of the above categories. However, the Sabrent XTRM-Q we are looking at today is unique in falling into two categories in the above list. It is both a Thunderbolt 3 SSD and a USB 3.2 Gen 2 SSD.

The XTRM-Q uses the Intel JHL7440 (Titan Ridge) Thunderbolt 3 controller to interface with the host system. Similar to the JHL6xxx Alpine Ridge host controllers, Titan Ridge also has a built-in xHCI controller that enables it to act as a USB 3.2 Gen 2 host. When used in a device configuration (i.e, in docks or peripherals), Titan Ridge has an extra feature not available in Alpine Ridge - a USB 3.2 Gen 2 downstream interface. Sabrent has taken advantage of this with a nifty tweak in the standard Thunderbolt 3 SSD reference design. The USB 3.2 Gen 2 downstream port is connected to the upstream interface of a USB to NVMe bridge chip (a Realtek 9210PD in all likelihood, though Tom's Hardware reports it as Realtek 9108B). Depending on the host to which the drive is connected (reported by the JHL7440), the PCIe 3.0 x4 lanes of the NVMe SSD are connected to either the JHL7440's downstream PCIe 3.0 x4 lanes or the Realtek bridge chip's PCIe 3.0 x4 lanes.

The Sabrent Rocket XTRM-Q's compatibility with both Thunderbolt 3 and USB ports while providing different performance profiles made for an interesting evaluation exercise. The SSD also happens to be the first we have evaluated with Intel's Titan Ridge controller. Based on these aspects, we evaluated the XTRM-Q models as well as a host of other SSDs with the following host controllers:

• Thunderbolt 3 : Intel Alpine Ridge (JHL6540)
• Thunderbolt 3 : Intel Titan Ridge (JHL 7540)
• USB 3.2 Gen 2 : ASMedia ASM2142

Additional details are available further down in the sub-section dealing with our testbed setup and evaluation methodology.

The various graphs in this piece compare and contrast the performance of different external SSDs when used with different host ports. The complete list is provided below, with the host specified in brackets. Some entries do not have a host entry - the numbers presented for those are from its evaluation with our standard testbed using the Alpine Ridge (JHL6540) host.

• Sabrent Rocket XTRM-Q 4TB [JHL6540]
• Sabrent Rocket XTRM-Q 4TB [ASM2142]
• Crucial Portable SSD X8 2TB
• DIY TB3 SSD [TEKQ Rapide - WD Black SN750] [JHL6540]
• DIY TB3 SSD [TEKQ Rapide - WD Black SN750] [JHL7540]
• OWC Envoy Pro EX TB3 2TB [JHL6540]
• OWC Envoy Pro EX USB-C 2TB
• Plugable TBT3-NVME2TB 2TB [JHL6540]
• Sabrent Rocket Nano Rugged 2TB
• Sabrent Rocket XTRM-Q 2TB [ASM2142]
• Sabrent Rocket XTRM-Q 2TB [JHL6540]
• Sabrent Rocket XTRM-Q 2TB [JHL7540]
• Sabrent Rocket XTRM-Q 4TB [JHL7540]
• SanDisk Extreme PRO Portable SSD v2 2TB [ASM3242]
• SanDisk Extreme PRO Portable SSD v2 2TB [JHL6540]

A quick overview of the internal capabilities of the storage devices is given by CrystalDiskInfo.

Drive Information

Sabrent Rocket XTRM-Q 4TB [JHL6540]Sabrent Rocket XTRM-Q 4TB [ASM2142]Crucial Portable SSD X8 2TBDIY TB3 SSD [TEKQ Rapide - WD Black SN750] [JHL6540]DIY TB3 SSD [TEKQ Rapide - WD Black SN750] [JHL7540]OWC Envoy Pro EX TB3 2TB [JHL6540]OWC Envoy Pro EX USB-C 2TBPlugable TBT3-NVME2TB 2TB [JHL6540]Sabrent Rocket Nano Rugged 2TBSabrent Rocket XTRM-Q 2TB [ASM2142]Sabrent Rocket XTRM-Q 2TB [JHL6540]Sabrent Rocket XTRM-Q 2TB [JHL7540]Sabrent Rocket XTRM-Q 4TB [JHL7540]SanDisk Extreme PRO Portable SSD v2 2TB [ASM3242]SanDisk Extreme PRO Portable SSD v2 2TB [JHL6540]Expand All

The Sabrent Rocket XTRM-Q uses standard PCIe 3.0 x4 NVMe drives internally. The bridge chip configuration allows for S.M.A.R.T passthrough and the SSDs support TRIM to maintain  optimal performance. The internal SSD is actually the Sabrent Rocket Q that was reviewed earlier this month.

Testbed Setup and Testing Methodology

Evaluation of DAS units on Windows is done with a Hades Canyon NUC configured as outlined below. We use one of the rear USB Type-C ports enabled by the Alpine Ridge controller for both Thunderbolt 3 and USB devices. However, to force the usage of the USB 3.2 Gen 2 interface in the Rocket XTRM-Q, the SSD was connected to the front USB Type-C port enabled by the ASMedia ASM2142 controller.

We also evaluated the performance of some of the Thunderbolt 3 SSDs with a Titan Ridge host - the Ghost Canyon NUC. These SSDs carry a JHL7540 tag in their graph entries. The configuration of the Ghost Canyon NUC used for benchmarking purposes is specified below.

Our evaluation methodology for direct-attached storage devices adopts a judicious mix of synthetic and real-world workloads. While most DAS units targeting a particular market segment advertise similar performance numbers and also meet them for common workloads, the real differentiation is brought out on the technical side by the performance consistency metric and the effectiveness of the thermal solution. Industrial design and value-added features may also be important for certain users. The remaining sections in this review tackle all of these aspects after analyzing the features of the drives in detail.