Portable flash-based storage solutions are one of the growing segments in the direct-attached storage market. The emergence of 3D NAND with TLC and QLC has brought down the cost of such drives. NAND manufacturers like Western Digital, Samsung, and Crucial/Micron who also market portable SSDs have an inherent advantage in terms of vertical integration. However, the current pace of progress in flash memory has led to competitively priced offerings even from vendors who need to buy flash in the open market. ADATA and HP (Multipointe / Biwin) are two such vendors in this space. Today’s review takes a look at six different portable SSDs – three each from ADATA and HP – forming the bulk of their 2020 portfolio of external flash storage solutions.
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.x), we now have palm-sized flash-based storage devices capable of delivering 2GBps+ speeds. While those speeds can be achieved with Thunderbolt 3, mass-market devices have to rely on USB. Entry-level USB drives utilize a flash controller with a direct USB interface, while the mid-range and high-end ones use flash packages behind either a SATA or NVMe SSD controller in conjunction with a SATA/NVMe-USB bridge. Depending on the target market, vendors use bridges with either a USB 3.2 Gen 1 or USB 3.2 Gen 2 host interface. Recently, we have seen a few devices come with USB 3.2 Gen 2×2 interfaces also.
HP Portable SSDs (from L to R: P500, P700, P600)
ADATA External SSDs (from L to R: SC680, SE800, SE760)
From a performance viewpoint, the devices being considered today fall under two categories that are referred to here on as 1GBps-class and 500MBps-class. The former ones use NVMe SSDs behind a USB 3.2 Gen 2 bridge, while SATA SSDs (or even direct flash packages) behind a USB 3.2 Gen 1 or Gen 2 bridge make up the latter typically. We updated our benchmark programs set for direct-attached storage devices earlier this year, and subjected the following new devices to our refreshed evaluation scheme:
- ADATA SE800 1TB
- HP P700 1TB
- ADATA SE760 1TB
- ADATA SC680 960GB
- HP P600 500GB
- HP P500 500GB
While the 500MBps-class drives are only compared against each other, the 1GBps-class ones are pitted against the following external SSDs that were reviewed earlier:
- Crucial Portable SSD X8 1TB
- Lexar SL100 Pro 1TB
- Samsung Portable SSD T7 Touch 1TB
- SanDisk Extreme Pro Portable SSD 1TB (2019)
A quick overview of the internal capabilities of the 1GBps-class drives is given by CrystalDiskInfo.
|1GBps-Class Drives Information|
The ADATA SE800 and HP P700 are both revealed to be NVMe drives behind a UASP-supporting USB bridge, which is along expected lines. The ADATA SE760 screenshot shows that the device internally uses an ADATA SX6000LNP SSD, which happens to be the ADATA XPG SX6000 Lite PCIe 3.0 x4 M.2 NVMe SSD. Other than that, we have the customary S.M.A.R.T passthrough confirmation.
CrystalDiskInfo statistics are available only for the ADATA SC680 and HP P600 in the 500MBps-class set – these are the ones using a SATA SSD behind a USB bridge. The HP P500, as we shall see in the teardown later, uses a USB flash controller and doesn’t report any information that can be parsed by the tool.
|500MBps-Class Drives Information|
Both the ADATA SC680 and HP P600 have S.M.A.R.T information being passed on from the SATA SSD side through the USB bridge. The ADATA SSD seems to have better support for monitoring compared to the P600’s multiple vendor-specific fields. However, both drives supported TRIM when tested in practice.
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.
|AnandTech DAS Testbed Configuration|
|CPU||Intel Core i7-8809G
Kaby Lake, 4C/8T, 3.1GHz (up to 4.2GHz), 14nm+, 8MB L2
|Memory||Crucial Technology Ballistix DDR4-2400 SODIMM
2 x 16GB @ 16-16-16-39
|OS Drive||Intel Optane SSD 800p SSDPEK1W120GA
(118 GB; M.2 Type 2280 PCIe 3.0 x2 NVMe; Optane)
|SATA Devices||Intel SSD 545s SSDSCKKW512G8
(512 GB; M.2 Type 2280 SATA III; Intel 64L 3D TLC)
|Chassis||Hades Canyon NUC|
|PSU||Lite-On 230W External Power Brick|
|OS||Windows 10 Enterprise x64 (v1909)|
|Thanks to Intel for the build components|
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.
Prior to looking at the usage characteristics of the various drives, it is helpful to compare their specifications and also take a look at the internals. All the 1GBps-class drives discussed in this review adopt the strategy of placing a NVMe SSD controller behind a USB 3.2 Gen 2 bridge chip.
|1GBps-Class Direct-Attached Storage Characteristics|
|Upstream Port||USB 3.2 Gen 2 Type-C||USB 3.2 Gen 2 Type-C|
|Bridge / Controller||ASMedia ASM2362 + Innogrit IG5208||JMicron JMS583 + HP H8098 (Silicon Motion SM2263EN)|
|Flash||Micron 64L 3D TLC||Micron 64L 3D TLC|
|Power||Bus Powered||Bus Powered|
|Physical Dimensions||72.7 mm x 44 mm x 12.2 mm||65 mm x 92 mm x 9.2 mm|
|Weight||40 grams (without cable)||58 grams (without cable)|
|Cable||20 cm USB 3.2 Gen 2 Type-C to Type-C
20 cm USB 3.2 Gen 2 Type-C to Type-A
|20 cm USB 3.2 Gen 2 Type-C to Type-A
Type-A to Type-C Adaptor
The ADATA SE800 is the lightest of the lot, coming in at 40g, compared to the 95g of the SE760 model (which integrates a separate M.2 SSD). The HP P700 is similar to the ADATA SE800, Lexar SL100 Pro, and the Samsung T7 Touch in integrating the flash, SSD controller, and the USB bridge on the same board. This enables the HP P700 to come in at 58g, similar to that of the Samsung T7 Touch. The ADATA SE800 uses an InnoGrit IG5208 SSD controller behind the ASMedia ASM2362 bridge. The HP P700 and ADATA SE760 both use the JMicron JM583 bridge, though the controllers are different – a rebranded Silicon Motion SM2263EN for the former and the Realtek RTS5763DL for the latter. The cable lengths for all the new SSDs being covered today are the same – 20cm. Interestingly, HP provides a Type-C to Type-A cable, and a Type-C to Type-A adaptor, while the usual trend is to pack a single Type-C to Type-C cable and a Type-C to Type-A adaptor. The ADATA SE800 stands out for its ruggedness with an IP68 rating. Other than the SanDisk Extreme Pro with its IP55 rating, none of the other SSDs in the above list claim any sort of ingress protection.
Two of the 500MBps-class devices being considered today use the JMicro JMS580 bridge and a Silicon Motion SM2259XT (DRAM-less) SSD controller for the SATA side of things. The HP P600 uses a rebranded version of the controller. All three use Micron’s 64L 3D TLC flash. The HP P500 uses a USB flash controller (again, a Silicon Motion die in a rebranded package).
|500MBps-Class Direct-Attached Storage Characteristics|
|Upstream Port||USB 3.2 Gen 1 Type-C||USB 3.2 Gen 1 Type-C|
|Bridge / Controller||JMicron JMS580 + Silicon Motion SM2259XT||JMicron JMS580 + HP H6158 (Silicon Motion SM2259XT?)|
|Flash||Micron 64L 3D TLC||Micron 64L 3D TLC|
|Power||Bus Powered||Bus Powered|
|Physical Dimensions||86.7 mm x 61 mm x 10 mm||65 mm x 92 mm x 9.2 mm|
|Weight||35 grams (without cable)||58 grams (without cable)|
|Cable||20 cm USB 3.2 Gen 2 Type-C to Type-C
20 cm USB 3.2 Gen 2 Type-C to Type-A
|20 cm USB 3.2 Gen 2 Type-C to Type-A
Type-A to Type-C Adaptor
The ADATA SC680 is the lightest, coming in at 25g. The HP P500 and P600 both have a more sturdy look and feel. The cables are similar to the ones supplied with the vendor’s 1GBps-class drives. The key aspect in the above table is the absence of S.M.A.R.T passthrough, TRIM support, and UASP support in the USB flash controller-based HP Portable SSD P500.
Additional details for each of the devices above, along with teardown photographs, are available in the sub-sections below.
The differentiating aspect of the ADATA SE800 is its IP68 rating and MIL-STD-810G – 516.6 shock-proofing certification. ADATA has reused the case design from the SE730 (2016 family) for the SE800. The gallery below presents some of the teardown pictures of the SE800.
There are four flash packages (two on either side) on the board. The InnoGrit 5208 (Shasta) is a PCIe 3.0 x2 DRAM-less SSD controller, and it interfaces with the flash packages on one side and an ASMedia ASM2362 USB 3.1 Gen 2 bridge on the other side. ADATA claims speeds of up to 1000 MBps for the SE800.
The internals also show two haphazardly placed thermal pads – one atop the ASMedia bridge, and another on one side of one of the ADATA flash packages. As we shall see further down, the thermal behavior of the internal board leaves a lot to be desired.
ADATA introduced the SE760 a few months after the launch of the SE800. It is a run of the mill USB 3.2 Gen 2 NVMe SSD, using separate boards for the bridge chip and the SSD, with the latter being a standard M.2 2280 NVMe SSD. The XPG SX6000 Lite used in the SE760 is a DRAM-less entry-level SSD. Unlike the SE800, the SE760 doesn’t have any ingress protection, but the industrial design is sleek and attractive. The gallery below presents some of the teardown pictures of the SE760.
There are four Micron flash packages on the SX6000 Lite along with the Realtek RTS5763DL SSD controller. board. The controller is a mainstream DRAM-less offering from Realtek. The SSD interfaces with a JMicron JMS583 bridge on the main board. ADATA claims speeds of up to 1000 MBps for the SE760.
The internals show a single thermal pad on the main board. Interestingly, the only pad interfaces with empty areas of the PCB on both the main as well as the SSD gum-stick. It is evident that the thermal solution is at the wrong place, and as we shall see further down, the temperature of the board components are not pleasant when the device is subject to stressful traffic.
The SC680 is ADATA’s entry level offering in the external SSD market. The slimness and lightweight nature are touted by ADATA as selling points for the drive. It integrates a SATA SSD and a USB bridge on a single PCB. The gallery below presents some of the teardown pictures of the SC680.
There are four flash packages (two on each side of the board). The controller used is the DRAM-less Silicon Motion SM2259XT, with the JMicron JMS580 doing the bridge duties. ADATA claims speeds of up to 530 MBps for the SC680.
There is no thermal solution to speak of, and the performance profile of the device leads us to believe that one might not be strictly necessary. The plastic casing ensures that any generated heat doesn’t really surprise the user while handling the device.
The P700 is HP’s flagship offering in the USB external storage space. The uniqueness of the P700 (as well as the P600 discussed below) lies in its cable management design. A magnetic casing (with dimensions similar to that of the main drive) is supplied to store the cable and adaptor along with the drive itself. It is strong enough for carrying around both the drive and the cable casing together, while also being easy enough to separate for actual usage. The other interesting aspect is the adaptor – while vendors have typically provided Type-C to Type-C cables, along with a Type-C to Type-A adaptor (most Type-C to Type-A adaptors are not legitimate as per USB-IF specifications), HP supplies a Type-C to Type-A cable, along with a Type-A to Type-C adaptor. The P700 integrates a NVMe SSD and a USB bridge on a single PCB. The gallery below presents some of the teardown pictures of the P700.
There are two flash packages, Micron-branded DRAM, and a HP H8098 (re-branded Silicon Motion controller) on one side of the board. The other side is practically empty (with the blank flash package slots potentially being used in higher-capacity versions).The JMicron JMS583 performs the bridging duties. HP claims speeds of up to 1000 MBps for the P700.
A thermal pad is affixed to the inner side of the metal casing and interfaces with the flash packages as well as the SSD controller. Based on this thermal solution, we do not expect any surprises in our thermal stress tests described further down.
The P600 targets the same market segment as that of the ADATA SC680. Similar to the SC680, it also adopts a single-PCB design for a DRAM-less SATA SSD behind a USB bridge. In terms of external appearance, it is quite similar to the P700 as can be seen from the teardown pictures below.
There are four flash packages on one side of the board. The controller used is the DRAM-less HP H6158 (re-branded Silicon Motion SM2259XT, in all likelihood), with the JMicron JMS580 doing the bridge duties. HP claims speeds of up to 560 MBps for the P600.
There are two strategically placed thermal pads attempting to cover all flash packages as well as the SSD controller. At first glance, considering the performance profile of the device, this looks acceptable. Nevertheless, the real-world performance of this thermal solution is worthy of the additional investigation reported in a later section.
The P500 is an entry-level portable SSD with an industrial design reminiscent of the Samsung T1 from 2015. It doesn’t come with magnetic cable-holder, but the cable/adaptor combination supplied alongwith is the same as the ones for the P600 and P700. The internal reveal a single-PCB design with a USB flash controller and a separate and a Type-C switch. The gallery below presents some of the teardown pictures for the P500.
There are four flash packages on one side of the board. The controller used is the HP H3808 (re-branded Silicon Motion SM3280), with the EtronTech EJ179V for implementing the Type-C support. HP claims speeds of up to 370 MBps for the P500.
There is no thermal solution necessary for this performance profile. The usage of a USB flash controller also precludes the collection of interesting device characteristics during the course of usage. It is interesting to see HP utilize a USB flash drive controller in a device marketed as a portable SSD.
Most USB 3.1 Gen 2 drives with NVMe SSDs claim speeds of around 1000 MBps, and these are backed up by the ATTO benchmarks provided below. Unfortunately, these access traces are not very common in real-life scenarios.
|1GBps-Class Drives Performance Benchmarks – ATTO|
The reads for the ADATA SE800 and SE760, as well as the HP P700 come in at around 985 MBps, while the writes for the P700 win out at 955 MBps. The SE800 tops out at around 885 MBps, while the SE760 can reach only 780 MBps.
CrystalDiskMark, despite being a canned benchmark, provides a better estimate of the performance range with a selected set of numbers. As evident from the screenshot below, the performance can dip to as low as 14MBps for random 4K reads.
|1GBps-Class Drives Performance Benchmarks – CrystalDiskMark|
The HP P700 again comes out on top with a good balance of read and write speeds for the sequential access case that forms the bulk of typical DAS usage – 1030 MBps / 977 MBps, compared to the ADATA SE800’s 1027 / 916 MBps and SE760’s 1026 / 822 MBps.
SATA SSDs behind a USB 3.1 Gen 2 bridge claim speeds of around 550 MBps, while traditional USB flash controllers top out around 350 MBps. The ATTO benchmarks for the ADATA SC680, HP P600, and HP P500 provided below back up those claims.
|500MBps-Class Drives Performance Benchmarks – ATTO|
The HP P600 comes out on top by a fine margin in the ATTO numbers – 530 / 482 MBps, compared to the ADATA SC680’s 512 / 472 MBps. The P500’s 344 / 203 MBps numbers are not surprising given the USB flash controller in the device.
|500MBps-Class Drives Performance Benchmarks – CrystalDiskMark|
CrystalDiskMark provides a better estimate of the performance range with a selected set of numbers. As evident from the screenshots above, the performance can dip to as low as 7 MBps for random writes in the HP P500. The HP P600 provides better peak numbers (554 / 491 MBps) compared to the ADATA SC680 (532 / 487 MBps). The HP P500 clocks in at 350 / 217 MBps for sequential reads and writes.
Our testing methodology for DAS units takes into consideration the usual use-case for such devices. The most common usage scenario is transfer of large amounts of photos and videos to and from the unit. Other usage scenarios include the use of the DAS as a download or install location for games and importing files directly off the DAS into a multimedia editing program such as Adobe Photoshop. Some users may even opt to boot an OS off an external storage device.
The AnandTech DAS Suite tackles the first use-case. The evaluation involves processing three different workloads:
- Photos: 15.6 GB collection of 4320 photos (RAW as well as JPEGs) in 61 sub-folders
- Videos: 16.1 GB collection of 244 videos (MP4 as well as MOVs) in 6 sub-folders
- BR: 10.7 GB Blu-ray folder structure of the IDT Benchmark Blu-ray
Each workload’s data set is first placed in a 25GB RAM drive, and a robocopy command is issued to transfer it to the DAS under test (formatted in NTFS). Upon completion of the transfer (write test), the contents from the DAS are read back into the RAM drive (read test). This process is repeated three times for each workload. Read and write speeds, as well as the time taken to complete each pass are recorded. Bandwidth for each data set is computed as the average of all three passes.
The first set of graphs is for the 1GBps-class drives. The Crucial X8 wins out on the read benchmarks, but the HP P700 comes out on top in quite a few of the tests. The ADATA SE800 and SE760 come in the middle of the pack.
Moving on to the 500MBps-class drives, we see the ADATA SC680 and HP P600 deliver almost similar numbers across the board. The HP P500 lags well behind, but that is only to be expected.
It can be seen that there is no significant gulf in the numbers between the different units in each performance class. Ideally, the HP P500 should be in its own sub-400 MBps class. For all practical purposes, the casual user will notice no difference between the drives in each set in the course of normal usage.However, power users may want to dig deeper to understand the limits of each device. To address this concern, we also instrumented our evaluation scheme for determining performance consistency.
Aspects influencing the performance consistency include SLC caching and thermal throttling / firmware caps on access rates to avoid overheating. This is important for power users, as the last thing that they want to see when copying over 100s of GB of data is the transfer rate going down to USB 2.0 speeds.
In addition to tracking the instantaneous read and write speeds of the DAS when processing the AnandTech DAS Suite, the temperature of the drive was also recorded at the beginning and end of the processing. In earlier reviews, we used to track the temperature all through. However, we have observed that SMART read-outs for the temperature in NVMe SSDs using USB 3.2 Gen 2 bridge chips end up negatively affecting the actual transfer rates. To avoid this problem, we have restricted ourselves to recording the temperature at either end of the actual workloads set. The graphs below present the recorded data for the 1GBps-class drives.
|1GBps-Class Drives Performance Consistency and Thermal Characteristics|
The first three sets of writes and reads correspond to the photos suite. A small gap (for the transfer of the video suite from the internal SSD to the RAM drive) is followed by three sets for the video suite. Another small RAM-drive transfer gap is followed by three sets for the Blu-ray folder. An important point to note here is that each of the first three blue and green areas correspond to 15.6 GB of writes and reads respectively. The ADATA SE800 and SE760 both take 600s+ finish processing the suite, and end up at temperatures of 73C and 64C respectively. On the other hand, the HP P700 stays cool to finish processing the suite in around 570s without breaking a sweat (starting at 35C and ending at 36C). The irregularities in the write speeds of the ADATA SE800 and SE760 for the video and Blu-ray folder components point to thermal throttling at play.
On the 500MBps-class drives front, we see the ADATA SC680 and HP P600 both take 850s+ to finish processing the suite. The write speeds for different components are consistent, though the absolute temperatures are worse for the ADATA SC680 due to its plastic enclosure.
|500MBps-Class Performance Consistency and Thermal Characteristics|
The HP P500 is again a mis-fit here. The reads are very consistent across all components, but the writes average only around 120 MBps with swings between 10 and 190 MBps. This is likely due to the behavior of the USB flash controller rather than any thermal aspect. The lack of S.M.A.R.T in the HP P500 meant that we could not record any internal temperature measurements for the drive.
There are a number of storage benchmarks that can subject a device to artificial access traces by varying the mix of reads and writes, the access block sizes, and the queue depth / number of outstanding data requests. We saw results from two popular ones – ATTO, and CrystalDiskMark – in a previous section. More serious benchmarks, however, actually replicate access traces from real-world workloads to determine the suitability of a particular device for a particular workload. Real-world access traces may be used for simulating the behavior of computing activities that are limited by storage performance. Examples include booting an operating system or loading a particular game from the disk.
PCMark 10’s storage bench (introduced in v2.1.2153) includes four storage benchmarks that use relevant real-world traces from popular applications and common tasks to fully test the performance of the latest modern drives:
- The Full System Drive Benchmark uses a wide-ranging set of real-world traces from popular applications and common tasks to fully test the performance of the fastest modern drives. It involves a total of 204 GB of write traffic.
- The Quick System Drive Benchmark is a shorter test with a smaller set of less demanding real-world traces. It subjects the device to 23 GB of writes.
- The Data Drive Benchmark is designed to test drives that are used for storing files rather than applications. These typically include NAS drives, USB sticks, memory cards, and other external storage devices. The device is subjected to 15 GB of writes.
- The Drive Performance Consistency Test is a long-running and extremely demanding test with a heavy, continuous load for expert users. In-depth reporting shows how the performance of the drive varies under different conditions. This writes more than 23 TB of data to the drive.
Despite the data drive benchmark appearing most suitable for testing direct-attached storage, we opted to run the full system drive benchmark as part of our evaluation flow. Many of us use portable flash drives as boot drives and storage for Steam games. These types of use-cases are addressed only in the full system drive benchmark.
The Full System Drive Benchmark comprises of 23 different traces. For the purpose of presenting results, we classify them under five different categories:
- Boot: Replay of storage access trace recorded while booting Windows 10
- Creative: Replay of storage access traces recorded during the start up and usage of Adobe applications such as Acrobat, After Effects, Illustrator, Premiere Pro, Lightroom, and Photoshop.
- Office: Replay of storage access traces recorded during the usage of Microsoft Office applications such as Excel and Powerpoint.
- Gaming: Replay of storage access traces recorded during the start up of games such as Battlefield V, Call of Duty Black Ops 4, and Overwatch.
- File Transfers: Replay of storage access traces (Write-Only, Read-Write, and Read-Only) recorded during the transfer of data such as ISOs and photographs.
PCMark 10 also generates an overall score, bandwidth, and average latency number for quick comparison of different drives. The sub-sections in the rest of the page refrence the access traces specified in the PCMark 10 Technical Guide.
Booting Windows 10
The read-write bandwidth recorded for each 1GBps-class drive in the boo access trace is presented below.
The HP P700 overtages the X8 by 2MBps, while the other drives including the two new ADATA ones are clustered between 104 MBps and 112 MBps. Given the amount of data traffic involved, the gulf is unlikely to result in a major difference in the boot times with various drives. The equivalent graph for the 500MBps-class drives is shown below.
The HP P600 comes out miles ahead of the SC680, while the P500 cuts a sorry figure.
The read-write bandwidth recorded for each 1GBps-class drive in the sacr, saft, sill, spre, slig, sps, aft, exc, ill, ind, psh, and psl access traces are presented below.
The HP Portable SSD P700 emerges as a top performer (sometimes by a significant margin) in almost all of the creative workloads. The case for the HP P600 is similar in the 500MBps-class drives set below.
The read-write bandwidth recorded for each 1GBps-class drive in the exc and pow access traces are presented below.
The HP P700 performs well in the office workloads too, though the lead is not quite as significant as what was seen in the previous workloads set. The HP P600 does perform signficantly better than the ADATA SC680 in the 500MBps-class, though.
The read-write bandwidth recorded for each 1GBps-class drive in the bf, cod, and ow access traces are presented below.
The Crucial X8 and HP P700 are neck-and-neck in the gaming workloads above, but the HP P600 emerges as the clear winner in the 500MBps-class.
Files Transfer Workloads
The read-write bandwidth recorded for each 1GBps-drive in the cp1, cp2, cp3, cps1, cps2, and cps3 access traces are presented below.
For pure reads or writes, the HP P700 performs well as seen in previous sections. However, once mixed traffic starts coming in, both the HP P700 and ADATA SE800 suffer, with the former being affected more. The ADATA SE760 performs much better with mixed traffic compared to the other two drives.
On the 500MBps-class front, we see that the ADATA SC680 putting up a much better challenge, and even performing better than the HP P600 in a few cases.
PCMark 10 reports an overall score based on the observed bandwidth and access times for the full workload set. The score, bandwidth, and average access latency for each of the 1GBps-class drives are presented below.
The Crucial X8 and the HP Portable SSD P700 perform quite similarly as far as the practical PCMark 10 workload traces are concerned.
The HP Portable SSD P600 emerges as the best of the lot in the 500MBps-class set by a huge margin.
The performance of the drives in various real-world access traces as well as synthetic workloads was brought out in the preceding sections. We also looked at the performance consistency for these cases. Power users may also be interested in performance consistency under worst-case conditions, as well as drive power consumption. The latter is also important when used with battery powered devices such as notebooks and smartphones. Pricing is also an important aspect. We analyze each of these in detail below.
Worst-Case Performance Consistency
Flash-based storage devices tend to slow down in unpredictable ways when subject to a large number of small-sized random writes. Many benchmarks use that scheme to pre-condition devices prior to the actual testing in order to get a worst-case representative number. Fortunately, such workloads are uncommon for direct-attached storage devices, where workloads are largely sequential in nature. Use of SLC caching as well as firmware caps to prevent overheating may cause drop in write speeds when a flash-based DAS device is subject to sustained sequential writes.
Our Sequential Writes Performance Consistency Test configures the device as a raw physical disk (after deleting configured volumes). A fio workload is set up to write sequential data to the raw drive with a block size of 128K and iodepth of 32 to cover 90% of the drive capacity. The internal temperature is recorded at either end of the workload, while the instantaneous write data rate and cumulative total write data amount are recorded at 1-second intervals.
|1GBps-Class Drives: Sequential Write to 90% of Disk Capacity – Performance Consistency|
The ADATA SE800 starts off at around 800 MBps, but only for a very short time of less than 10s. However, it stays around 700 MBps for close to 3 minutes. The SLC cache size seems to be around 128GB, but the firmware behavior is not typical of a SLC-to-direct TLC write transition – rather, thermal throttling is likely at play here. The HP P700, on the other hand, sustains 850 MBps for 3 minutes – pointing to a SLC cache of around 150GB, before going down to 600 MBps. While the SE800 sustains around 600 MBps for the full test (despite the internal SSD reaching 96C, after starting at 53C), the P700 drops down to around 380 MBps after filling up more than half of the disk. The P700 temperature rise is more reasonable, thanks to the effective thermal solution – 33C to 45C. The ADATA SE760 exhibits significant thermal throttling – after staying at 760 MBps for around 8 minutes (starting at 44C) and writing around 365 GB, the speed drops down to the 25 – 300 MBps range. The drive ended up at 95C towards the end of the process. The thermal solution in both the SE800 and SE760 are responsible for the drives’ sorry performance in the performance consistency test.
|500MBps-Class Drives: Sequential Write to 90% of Disk Capacity – Performance Consistency|
The HP P600 exhibits better performance consistency in terms of delaying the SLC-to-TLC cliff compared to the ADATA SC680. The latter drops down to the 40 MBps range (from 400 MBps) after around 150GB of writes (compared to the P600’s drop from 430 MBps to 175 MBps after 120GB of writes). The P600 has another fall to 100 MBps further down, but is never as bad as the SC680. The P500’s behavior is dictated by the USB flash controller, and its low performance from the start of the test ensures that it doesn’t exhibit drastic performance issues in the consistency test.
Bus-powered devices can configure themselves to operate within the power delivery constraints of the host port. While Thunderbolt 3 ports are guaranteed to supply up to 15W for client devices, USB 2.0 ports are guaranteed to deliver only 4.5W (900mA @ 5V). In this context, it is interesting to have a fine-grained look at the power consumption profile of the various drives. Using the Plugable USBC-TKEY, the bus power consumption of the drives was tracked while processing the CrystalDiskMark workloads (separated by 30s intervals). The graphs below plot the instantaneous bus power consumption against time, while singling out the maximum and minimum power consumption numbers.
|1GBps-Class Drives: Power Consumption – CrystalDiskMark Workloads|
The ADATA SE800 has a 1W idling mode, making it suitable for use with battery-powered devices. On the other hand, the HP P700 and ADATA SE760 idle at around 1.5W and 2W respectively.
|Drive Power Consumption – CrystalDiskMark Workloads|
The ADATA SC680 and the HP P600 both operate in the 1W-2.8W interval, while the HP P500 idles at around 0.7W.
The price of flash-based storage devices tend to fluctuate quite a bit over time. However, the relative difference between different models usually doesn’t change. The table below summarizes the product links and pricing for the various units discussed in the review.
|External Flash Storage Devices (1GBps-Class) – Pricing|
|Product||Model Number||Capacity (GB)||Street Price (USD)||Price per GB (USD/GB)|
|ADATA SE800 1TB||ASE800-1TU32G2-CBK||1000||$130||0.13|
|ADATA SE760 1TB||ASE760-1TU32G2-CTI||1000||$150||0.15|
|Crucial Portable SSD X8 1TB||CT1000X8SSD9||1000||$150||0.15|
|HP P700 1TB||5MS30AA#ABC||1000||$175||0.175|
|Lexar SL100 Pro 1TB||LSL100P-1TBRBNA||1000||$190||0.19|
|Samsung Portable SSD T7 Touch 1TB||MU-PC1T0S/WW||1000||$190||0.19|
|SanDisk Extreme Pro Portable SSD 1TB||SDSSDE80-1T00-A25||1000||$190||0.19|
As the adage goes, one gets what one pays for – power users focused on performance need to look at the bottom half of the above table. That said, the current $130 pricing for the ADATA SE800 is somewhat of a steal, considering its IP68 rating. The performance might not satisfy the enthusiasts, but casual users should be more than happy with the value delivered for the money – this is despite the flawed thermal solution.
|External Flash Storage Devices (500MBps-Class) – Pricing|
|Product||Model Number||Capacity (GB)||Street Price (USD)||Price per GB (USD/GB)|
|ADATA SC680 960GB||ASC680-960GU32G2-CBK||960||$125||0.13|
|HP P500 500GB||7NL53AA#ABC||500||$75||0.15|
|HP P600 500GB||3XJ07AA#ABC||500||$80||0.16|
The current pricing of the ADATA SE800 renders the ADATA SC680 unattractive for purchase. Ideally speaking, the 500MBps-class drives need to carry a significant discount over the 1GBps-class ones (given that the latter can operate quite well even with legacy ports). We do not see that with the pricing on the P500 and P600 either.
After careful analysis of various aspects (including benchmark numbers, temperatures, power consumption, and pricing), it is clear that there is no single external SSD unit that wins on all metrics.
Casual users looking for a cheap deal could go in for the ADATA SE800 – it is the cheapest by a significant margin. However, power users would do well to stay away from it because the performance of the unit is abysmal after the SLC cache runs out, and the thermal solution is flawed. The ADATA SE760, unfortunately, doesn’t merit recommendation – it doesn’t stand out in any of the departments. The ADATA SE800 and SC680, along with the HP Portable SSD P600 and P500 are suitable for use with mobile devices, as they are quite power efficient. The SE800 wins out on the performance side among these four models. Based on the pricing aspect, the 500MBps-class devices should probably be avoided.
From the viewpoint of raw performance for power users with reasonable traffic requirements, the HP Portable SSD P700 is perfect. In fact, our only complaint against it is the lack of performance consistency for sustained sequential writes that span almost the entire disk. For extreme use-cases such as those, our recommendation continues to be with the SanDisk Extreme Pro Portable SSD (2019 model) despite its pricing premium over the six new external SSDs considered in this review.