FireWire support on MacBook Pro M1 with OWC Thunderbolt 3 Dock

ProfessorVideo wrote:

I am using an OWC Thunderbolt 3 Dock to successfully connect a RAID array box to my M1 MBP via FireWire. I read that the new MacOS has dropped FireWire support, but does my Dock need it?

Your Dock already has it. FW800 support is built into the Dock.

I think you are asking if Tahoe doesn't support FW but your Dock does, will FW drives still work with the Dock. The answer is probably yes. The Firewire PHY is in the Dock. The Dock is connected to your Mac via Thunderbolt 3, so your Mac only "sees" the Thunderbolt connection to the Dock. All the outbound connections from the Dock (USB 3.1, FW, S/PDIF, MDP) are handled by the Dock.

That said, only time will tell ...

HWTech wrote:

I seriously doubt you will be able to access the Firewire drive unless your dock is more than just a simple dock and is translating the Firewire data stream to something else (what would that be though? Very doubtful ... wishing/hoping for it won't make it so).

The OP's Dock (OWC Thunderbolt 3 dock) has an upstream Thunderbolt 3 port and a downstream FW800 port. That means the dock itself has an integrated Thunderbolt-to-Firewire adapter (called the PHY) .. much like the Apple Thunderbolt 2 to Firewire adapter ... except in this case Thunderbolt 3 to Firewire.

Short of actual connection & trial I see no reason the Dock shouldn't continue to provide access to FW800 drives when the Dock is connected to a Mac running Tahoe.

But if the OP's RAID Enclosure supports USB 3.0 or later I would strongly advocate using USB 3.x instead of Firewire.

ProfessorVideo wrote:

As I said - I am connecting a RAID array box to the Dock via FireWire (800). I have a horrible suspicion that only I will know if it works with Tahoe! There cannot be many others trying to do the same thing.

If I try it - how easy is it to reverse back to Sequoia?

I seriously doubt you will be able to access the Firewire drive unless your dock is more than just a simple dock and is translating the Firewire data stream to something else (what would that be though? Very doubtful ... wishing/hoping for it won't make it so).

As others have mentioned, many Firewire drives tended to have a USB port along with a Firewire port to make it more versatile. Maybe you will be lucky and it is a USB3 port instead of a USB2 port. Either way, most Firewire drives will most likely be very slow, so why not just purchase a new USB3 drive & transfer the files on the Firewire drive to the new drive? It will be faster and you will be getting rid of a drive that is most likely wearing out anyway.

Trying to downgrade the OS will be a major pain if you install Tahoe over top of Sequoia. Focus on the correct problem......getting rid of the Firewire drive if it does not have a USB3 interface.

https://xyproblem.info/

However, if you insist on doing things the hard way....here is a slightly easier method of testing....

If you have at least 90GB+ of Free storage space on your boot drive (you may need even a bit more since the Tahoe installer is almost 17GB in size), then you can create a new APFS volume & install Tahoe into it to see what happens. It is just as easy to delete that new APFS volume once testing is complete. Just make sure you have at least 20GB or better yet 20%+ of Free storage space at all times (even that amount can disappear quickly even under simple basic workloads).

Unfortunately the only places within macOS where you can actually see the Free storage space value is in Disk Utility or the Apple System Profiler. Unfortunately the "Available" storage value shown everywhere within macOS is very misleading and in macOS "Available" is not synonymous with Free.

Or you can install Tahoe to an external USB3 SSD, but keep in mind the hidden early boot files on the internal SSD will be updated to Tahoe versions regardless of where you install Tahoe (part of how an M-series Mac works). Keep in mind there are numerous reports of people having issues installing Tahoe (mostly on M3 Macs, but not always)....some of the solutions involve completely wiping the internal SSD with a DFU Firmware Restore which requires access to another Mac running macOS Tahoe (or possibly Sequoia).

What is the make/model of your RAID Array enclosure, and does it have any connections other than FW800?

I have an OWC Mercury Rack Pro with FW800 that I used that way for many years, but it also has a USB 3.0 connection (5Gbps) and it's actually faster than FW800. I have switched to using the USB connection.

What brand and model is your RAID array box..?

Many of those RAID boxes have both FireWire 800 and a USB 3.0 connection.

If it has a USB 3.0 connection..?

1) USB 3.0 is faster than the FireWire 800

2) USB 3.0 will not become incompatible like FireWire

Are you using a Firewire device, or a Firewire port/cable/adapter for anything? If not, then you are not using Firewire. If you are using Firewire, then do not upgrade past macOS 15.x Sequoia since macOS 26 Tahoe no longer supports Firewire.

Just because a device has a Firewire port does not mean anything if nothing is connected to the Firewire port or connector.

Thanks @MartinR.