Outrageous Speed with 8 SSDs in Dual Thunderbay 4 Minis: Speed vs Transfer Size

OWC Thunderbay Mini

Dual OWC Thunderbay 4 Mini units each with four OWC 960 GB Mercury Electra 6G SSDs were used for these tests.

Each Thunderbay 4 Mini was connected to a separate bus on the Mac Pro, thus allowing full performance to be delivered to each Thunderbay 4 Mini.

Speed vs transfer size

disktester run-sequential-suite
--iterations 5 --test-size 4GB --fill 0 --caching false --test-area 0% --xfer-steps 1 --starting-xfer 32K --ending-xfer 512MB

Transfer size has a huge influence on throughput, as shown.

• Small transfers gain little or no benefit from RAID, and might actually be slower than a single SSD.
• Somewhere around 256K transfers, a bump up in performance is seen.

Practical note: Photoshop still uses decades-old code oblivious to currrent technology, and limits transfers to ~1MB, so users will never see it go faster than the 1MB transfer speeds shown here (600MB/sec is the typical short-lived and erratic maximum).

High hardware performance requires highly tuned software to reap benefits.

Speed MB/sec vs transfer size with 8 SSDs in dual Thunderbay 4 Minis on 2013 Mac Pro