OWC Envoy Pro EX SSD: Speed vs Transfer Size

OWC Envoy Pro EX Thunderbolt 3
OWC Envoy Pro EX USB-C

MPG tested the 4TB OWC Envoy Pro EX Thunderbolt 3 and the 4TB OWC Envoy Pro EX USB-C. Capacities available from 240GB to 4TB for both models.

This page evaluates speed for various I/O transfer sizes of the OWC Envoy Pro EX Thunderbolt 3 vs the USB-C model, both 4TB capacity.

Test results: speed vs capacity

Test mule was the 2019 iMac 5K. The run-sequential-suite command of diglloydTools Disktester was used.

disktester run-sequential-suite -i 5 --test-size 4GB

Speed always varies with transfer size, whether on hard drives or SSDs. There is always overhead e.g., writing 1MB as thirty-two 32K transfers is far less efficient than writing 1MB as a single transfer). With RAID-0 and RAID-5, the striping aspect means that the transfer is split into blocks across drives, the “stripe size” being the determinant of how the transfer is split up.

As with the fill-volume results, the OWC Envoy Pro EX Thunderbolt 3 model easily outperforms the USB-C model for reads, doubling or tripling its performance for very small transfers (32/64/128/256K). Since small transfers (1MB and less) are by far the most common I/O sizes, this is highly significant for general purpose use.

For large transfers, the Thunderbolt 3 model is about 2.5X faster for reads, and about 44% faster for writes.

Assuming a Thunderbolt 3 port is available, it is a no-brainer in favor of the Thunderbolt 3 model unless minimizing size/weight is a primary consideration. The USB-C model is still worthy of praise—it achieves about a gigabyte per second in about 2/3 the size and weight, blazingly fast by most measures.

Vertical scale is MB/sec. Horizontal scale shows I/O transfer size.

OWC Envoy Pro EX Thunderbolt 3 and USB-C versions: speed vs transfer size