Thunderbolt on Windows with Asus, Intel and Promise

With up to a theoretical peak bandwidth of 1.25GB/s (10 Gbps) per Thunderbolt port, there’s no way four standard hard drives are going to tax the Thunderbolt connection, but we did some testing with the R4 running in RAID 5 and RAID 0 modes anyway.

RAID 5 DAS Performance with Thunderbolt Measuring bandwidth and throughput of Thunderbolt external storage

And just for good measure, we’ve got some comparison numbers from a OCZ Vertex 3 SSD connected to our test machine using an external USB 3.0 enclosure.

 

Promise Pegasus R4 RAID 5 (4x1TB)	Promise Pegasus R4 RAID 0 (4x1TB)	USB 3.0 SSD
Promise Pegasus R4 RAID 5 (4x1TB)	Promise Pegasus R4 RAID 0 (4x1TB)	USB 3.0 SSD

We only provide the USB 3.0 SSD data here as a point of reference, to show you what kind of performance can be expected from a basic USB 3.0 enclosure with a fast SSD installed, in our case a 480MB OCZ Vertex 3. Max theoretical throughput for this SSD is around 550MB/sec for reads and 525MB/sec for writes, so its close to the theoretical bandwidth of the USB 3.0 interface (625MB/s), which is typically never achieved but in practice performs closer to 400MB/s or around 3.2Gbit/s.

As you can see, although the Promise Pegasus R4 external RAID setup doesn't come close to approaching the theoretical peak of the Thunderbolt port, the array does perform very well. In RAID 5 mode, we saw transfer speeds in CrystalDiskMark approach 380MB/s. That number increased to 512MB/s with the four drives configured in RAID 0.

The ATTO Disk benchmark, showed a best case scenario transfer speed of over 900MB/s, but we only tested a small portion of the multi-terabyte volume. The CrystalDiskMark numbers are more indicative of real world sequential and random read/write performance.