Not all third party devices are compatible with M-series Macs and/or macOS. I'm not familiar with that brand so I cannot say whether it is compatible with Macs.
I have seen recent reports on this forum where one user mentioned they had issues with external drives unless those external drives were connected to a USB hub....that user happened to be using an unpowered hub, but it allowed their external drive to work. I'm guessing that the hub was acting like a filter/buffer which prevented the failure when connecting the drives directly to the Mac. I had a similar experience with a 2014 Mac Mini when using USB3 external drives.....if I didn't use a hub, then the USB ports on my Mini would become temporarily disabled until the computer was rebooted.
Your issue could also be caused by the cable being used. Have you tried using a high quality cable from a known & reputable brand?
It does concern me about the enclosure since the USB-C port is only marked as "Type-C" instead of being marked the appropriate symbol of the type of data transfer protocol it actually supports. It is ridiculous to mark it "Type-C" as it is evident by the connector itself. That port should either have a lightning bolt icon to indicate support for the Thunderbolt protocol, or it should have a trident symbol along with the USB version (3.x Gen y, or USB 4) and the speed it supports. Because of this, I would question the quality of this device and its compatibility.
Vernon Alexander wrote:
Is there a limit to how many drives can be accessed all at once?
macOS doesn't have a limitation that will affect you here.
Within that four bay enclosure when configured as JBOD? I don't know as it may depend on the device. What does their documentation say?
Why do I have to unplug the four enclosure drive in order to get the Mac to boot?
Apple computers scan all connected devices. Something with that scan is causing a problem.
Make sure you have the default Startup Disk in System Settings configured to be the internal macOS boot volume. If there is no default macOS Startup Disk, then the computer will scan everything for bootable volumes and make a choice on which one to select.
Could it be that these very old hard drives are having issues to lock up the system on startup?
Always a possibility. Another possibility is that one of the drives....especially an SSD could have compatibility issues with the enclosure. Not all SSDs are compatible with all devices.
Could it be this inexpensive USB C four drive enclosure from China?
Highly likely. You get what you pay for and most items from China are just cheap junk (cheap in both price & quality). Very few manufacturers actually provide quality products these days because they have to cheapen their quality products to compete with all the low cost junk everybody buys. Even traditionally good brands have cheapened their products in order to compete.
A two drive enclosure Thunderbolt 2 (3T and 1TSSD)
Sometimes multiple external devices even if connected to different physical ports on the computer can still cause compatibility issues between themselves. If you are daisy chaining them, then that possibility increases greatly.
Daisy chained to the Thunderbolt drive is a HDMI adapter that goes to a second monitor.
That could also potentially be causing a problem especially with a cheap Chinese product. Even a quality product may still have issues since there are various HDMI standards & protocols and lots of variations in monitors. I have found a lot of monitors these days don't even function well when connected directly to the computer without any other external devices connected. Unfortunately many products today are poorly designed and manufactured...even ones from name brands. Even Apple suffers from this disease these days.
The best way to troubleshoot a problem is by disconnecting all external devices except for those which are strictly necessary such as the Display and Keyboard & Mouse....plus the device you are testing. Even cables are extremely important.
Does this enclosure support Thunderbolt 3/4? If so, then you need to connect it to the rear USB-C ports on the Mini since they are the only USB-C ports which support the Thunderbolt protocol.
If the enclosure only supports the USB4 protocol, then the rear ports must be used as well.
If the enclosure only supports USB 3.x, then can be connected to the front USB-C ports. I have seen some people report issues when connecting USB drives to the rear ports on some of these M-series Desktop Macs.
