thunder bay 4 displayed Mac OS can't repair the disk.

Get Disk Warrior now.

It is the best chance at fixing the directory on this volume. All you do is run it on this volume to rebuild the directory.

Note: on the last step, you get an option to "replace" or Preview.

Use Preview. It mounts a pseudo volume on your desktop. Make sure all your files are there before you click the replace button, as you cannot undo this. Open a couple sample files, make sure nothing critical is missing, etc.

only then click replace.

I'm getting this error as well, but I have a M1 Mac and Diskwarrior has yet to be updated to work with it. Any suggestions?

If the volume mounts read only, then backup/restore. if it does not mount, then find an older computer to repair it with Disk Warrior. I do not know of any other tools that can rebuild damaged HFS directories.

If you have TechTool Pro, it is possible their new directory repair feature may work, but I have not had a damaged HFS directory in house recently to test this with.

@softraid-support I found an older Mac mini to try adn repair it. But I figured I needed to install Softraid, and I'm getting the softraid has suffered an interal error message and deleting the plist file, rebooting, re-installing, etc hasn't solved that issue.

@cmo

The driver we use to bundle with macOS would be enough for you to repair the volume if you run Disk Warrior the main difference is it cannot rebuild/report errors and writes are much slower. But the driver can mount your volume just fine.

Give Disk warrior a try. Then we do not have to worry about this issue.

I managed to get SoftRaid 5 XT running on it, and after ordering an older thunderbolt cable to run through the 2 to 3 adapter, I managed to get it to mount, and the rebuild appears to be working. 

Thanks.