I just bought my 4th external USB3 SSD for my MacBookPro. I obviously don’t use all of them together, I just was just constructing my latest external Sockle storage bay. This time it’s a 1TB SSD and it’s a generation T5. So this was a good moment to compare it to my previous T1 and T3 SSD drives. I use the Blackmagic Disk Speed Test app to get realistic read and write data transfer rates. I will round them off to the nearest multiple of 10MB/s.

Benchmark: internal 500GB SSD

We will compare all the disks with the performance of the internal SSD disk, which has a SATA-III connection (not the slower USB 3 connection): 560 MB/s write – 720 MB/s read speed.

EXTERNAL SAMSUNG SSD: T1/T3/T5

The T1 generation of SSD (in my case a 500GB) is the slowest: 260 MB/s write and 360 MB/s
  The T3 generation of SSD (I have 2 x 500GB ones) is a bit faster: 360 MB/s write and 400 MB/s read speed.
The last T5 generation of SSD (in my case a 1TB one) is the fastest: 420 MB/s write and 420 MB/s read speed. This is about 66% or 2/3 of the theoretical maximum transfer speed of USB3: 5Gbps or 625 MB/s

EXTERNAL HD: Lacie Porsche 1TB 2.5″ ‘classic’ hard drive

Just to get a feel of just how much better that is than the old ‘rotating magnetic’ disks: the speed of a brand new 2.5″ 1TB Lacie Porsche disk: 130 MB/s read and write speed. That is 1/3 of the speed of the Samsung T5 SSD, at about 1/4 of the cost (1TB: 100 euro vs 420 euro – Nov 2017).

ALL IN ONE TABLE

DISK WRITE SPEED READ SPEED
INTERNAL SSD (500GB) 560MB/s 710MB/s
EXTERNAL SSD (500GB T1) 260MB/s 360MB/s
EXTERNAL SSD (500GB T3) 360MB/s 400MB/s
EXTERNAL SSD (1000GB T5) 420MB/s 420MB/s
EXTERNAL HD (2TB Lacie Porsche) 130MB/s 130MB/s