ADATA SE730, SV620 and SC660 External SSDs Review

Performance Evaluation

Our performance evaluation scheme for direct-attached storage devices first takes a look at some synthetic benchmarks, followed by real-world use-cases. Prior to getting into the details of the benchmarks, we take a look at the testbed used to evaluate the external SSDs.

Testbed Setup and Testing Methodology

Evaluation of DAS units on Windows is done with the testbed outlined in the table below. For devices with a USB 3.1 Gen 2 (via a Type-C interface) connections (such as the ADATA SE730 250GB that we are considering today), we utilize the USB 3.1 Type-C port enabled by the Intel Alpine Ridge controller. It connects to the Z170 PCH via a PCIe 3.0 x4 link. For devices with a Type-A interface (via the supplied cable - such as the SC660 and SV620 presented in this review), we utilize a Type-C male to Type-A female converter cable rated for operation at USB 3.1 Gen 2 speeds.

The full details of the reasoning behind choosing the above build components can be found here. The list of DAS units used for comparison purposes is provided below.

• ADATA SE730 250GB
• ADATA SV620 480GB
• ADATA SC660 240GB
• Netac Z5 512GB
• Samsung Portable SSD T3 2TB
• SanDisk Extreme 500 240GB
• SanDisk Extreme 510 480GB
• SanDisk Extreme 900 1.92TB

Synthetic Benchmarks - Crystal DiskMark

ADATA claims read and write speeds of 550 MBps and 450 MBps respectively for the SE730. The corresponding numbers for the SC660 an SV620 are 420 MBps / 440 MBps. The access traces that can back up those numbers are unfortunately not very common in real-life scenarios.

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 20 MBps for 4K random reads in the SE730.

ADATA SE730 250GBADATA SV620 480GBADATA SC660 240GBNetac Z5 512GBSamsung Portable SSD T3 2TBSanDisk Extreme 500 240GB - USB 3.1SanDisk Extreme 510 480GBSanDisk Extreme 900 1.92TB

A comparison of the 4K random access numbers at low and high queue depths can also reveal UASP (USB-attached SCSI protocol) support. If the high queue depth numbers are significantly higher than the single outstanding transaction version, it implies that the DAS device supports native command queueing (NCQ) that is possible only if the bridge chip supports UASP. From the above numbers, it is clear that the SE730 supports UASP, while the SV620 and SC660 do not support the feature.

Benchmarks - robocopy and PCMark 8 Storage Bench

Our testing methodology for DAS units also 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. The minor usage scenario is importing files directly off the DAS into a multimedia editing program such as Adobe Photoshop.

In order to tackle the first use-case, we created three test folders with the following characteristics:

• 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 (the same that we use in our robocopy tests for NAS systems)

For the second use-case, we take advantage of PC Mark 8's storage bench. The storage workload involves games as well as multimedia editing applications. The command line version allows us to cherry-pick storage traces to run on a target drive. We chose the following traces.

• Adobe Photoshop (Light)
• Adobe Photoshop (Heavy)
• Adobe After Effects
• Adobe Illustrator

Usually, PC Mark 8 reports time to complete the trace, but the detailed log report has the read and write bandwidth figures which we present in our performance graphs. Note that the bandwidth number reported in the results don't involve idle time compression. Results might appear low, but that is part of the workload characteristic. Note that the same testbed is being used for all DAS units. Therefore, comparing the numbers for each trace should be possible across different DAS units.

The above benchmark numbers confirm our suspicions - the SV620 and SC660 perform very similar to each other and have significant penalty in scenarios involving sustained writes. The SE730 performs very nicely - comparable to other devices with a single SATA SSD inside them. The use of a USB 3.1 Gen 2 bridge chip enables it to come out with slightly better performance than most of the other USB 3.0-based external SSDs. Devices with RAID 0 SATA drives (such as the Netac Z5 and the SanDisk Extreme 900) perform better in most DAS workloads, but, that is expected.