As mentioned, with drives,
- Some old external drives may give you the choice of whether to connect via Thunderbolt or USB.
- In other cases, it may be possible to take drives out of Thunderbolt 1/2 enclosures and put them into new ones. This assumes that you have the skills to do this without causing static damage to the drives – and might not be an option with RAIDs where the RAID enclosure may have formatted drives in some funny, unique-to-it way.
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If you need to make a Thunderbolt connection to old Thunderbolt 1/2 devices, I believe there are only two options:
- The Apple Thunderbolt 3-to-2 adapter. It costs $50 and only translates Thunderbolt. It does not know how to make its TB2 side act as a plain Mini DisplayPort, and it does not carry significant amounts of power (and thus wouldn't let you connect a bus-powered TB3 SSD directly to a TB1/2-equipped Mac).
- The StarTech adapter. It costs $100 and appears to have all of the same limitations as the Apple adapter – plus an additional one: it is unidirectional. (Given this, I'm not sure why you would want to buy it.)
Nobody makes Thunderbolt 1 & 2 hubs any more. If you have Thunderbolt 1 & 2 gear that has Thunderbolt daisy-chaining ports, you could set up your equipment like
Mac --- TB3-to-2 adapter --- OldTBDevice1 --- OldTBDevice2 --- ...
to minimize the number of adapters you have to buy. But you're not going to find an adapter that has a TB3 input on one side and multiple TB1/2 ports on the other.