Loaders on External Drives not found when connected via hub

[Nap]

Just an issue of convenience, but I've found that 99% of the time, rEFInd is not able to find boot loaders and kernels on drives connected via a USB3 hub I have. I have tried using the scan_delay option, and though the pause message shows on screen, the loaders are not added to the list.

For example, I have a WD Elements 3TB disk plugged into my hub, and I discovered yesterday that it has a boot loader on it called tmbootpicker.efi.
Another example is the HD-U1604 drive I mentioned in an earlier question. When it's plugged in via the hub, it does not show in the boot menu, but when I plug it into my Mac directly, it is detected each time.

Do you think this is a Mac, hub, or maybe rEFInd issue? I personally suspect it's a Mac issue as I have essentially the same problem when I use the Option key while booting my Mac.

I'm just wondering if there is a way to overcome the problem.

[Roderick W. Smith]

rEFInd uses EFI system calls to detect disks and partitions, so the most likely reason for rEFInd to be missing the device is if the EFI in the computer hasn't detected it. If that detection is sporadic, the most likely explanation is that it's a hardware fault. This is more likely to be a flaky hub or cable than the computer itself, although I can't rule out a defective Mac (or a Mac design flaw). An EFI bug is also a possibility, but a fairly remote one.

The cheapest thing to try is to plug your existing hub into another port on the computer. If the problem clears up, then you can be pretty sure you've got a defective USB port -- maybe a bad trace, a loose connector, etc. If the USB hub has a fully-detachable cable, you could try swapping it out, too. Beyond that, I recommend you try another USB hub -- ideally a different brand. Make it a trusted brand name, too, not a generic eBay special.