Hi all, Context I recently bought an iMac 27' with 512 GB SSD internal drive. Mainly to be used for photography workflows (Lightroom & Photoshop). I am now looking for an external storage solution to manage the photo library, and let the internal SSD take care of catalogs and applications. I also keep in mind that the chosen storage solution will impact the backup strategy (to set up). A capacity of 4 TB storage will cover my needs. As you may know, the late 2015 iMac includes (2X) Thunderbolt 2 ports and (4X) USB 3.0 ports The first choice goes to external spinning hard drive(s) as no high speed transfer is required in my case (no work on video files expected), and for price reason. I have seen lot of interesting threads and articles, however the question remain the same to me: The question? if I plug an external spinning drive, as a standard of 64MB cache, 7200RPM, no RAID..., what is the real difference to use the Thunderbolt port against USB 3.0 port ? Why this question? - The transfert rates for ports : USB 3.0 = 5GB/s, Thunderbolt = 10GB/S, Thunderbolt 2 = 20GB/S - The transfert rates for external spinning drives are around 160-240 MB/s. As for example G-Drive with Thunderbolt 4TB is 245 MB/s and G-Drive G1 4 TB USB 3.0 is the same 245 MB/s (6 TO disk). What does it mean? - Using an external HDD, Thunderbolt would have no added value to go for, as the spinning drive will be the bottleneck of the chain, bringing 245MB/s max of transfer rate versus 10GB/s proposed by this port... - Thunderbolt ports could be used with SSD external drive to allow better read/write rate. For instance, I see SSD performs around 450 MB/s (no raid)...Which is still below the 10-20 GB/s proposed by TB. Need your help Am I correct to benchmark ports against drives transfer rates? Please let me know which storage solution you would recommend to me. What would be your advice for an associated backup strategy? Is there any difference between TB and USB 3.0 in real world, using external HDD or external SSD? Many thanks beforehand!