Failing Thunderbay 4?

[MrCheeto]

Been transferring about 20TB onto this thunderbolt 2 Thunderbay 4 (not mini) for about three weeks and right as I finished, last night it seems it disconnected for a moment. I woke up to find the disconnect error on the Mac but everything was mounted and working. I did some rsyncs and verified some things here and there and suddenly in the middle of an rsync I kept getting random disconnects.

Shut everything down, restart, about twenty-minutes later it starts random disconnects. Now I have a "MacOS can't rebuild" error. So I move from the Mac mini to the MacBook Pro. Exact same symptoms.

I tried multiple versions of SoftRAID (5, 6, 7) yet in every case, SoftRAID will say "multiple disks missing. Out of Sync. Rebuild required" and when I click rebuild in every version, literally NOTHING happens. 2 disks (raid 1+0) are good and mount and all the data is there. 2 others are the same but show out of sync.

Sometimes the disks won't even mount and I have to shut the bay down and try again.

Now here's the kicker. In SoftRAID you can send a command to light up the activity LED on the bay for each drive but it doesn't respond!

I have a feeling the proper amount of power isn't getting to the drives and could be a failing supply or something else. Normally when starting up you hear each drive spin-up and seek one after the other but now it sounds like they're all starting up simultaneously!

Power supply? No errors reported on any drives.

 

[MrCheeto]

Breakthrough.

For the past month or so, I've noticed that turning on the light in the room made the screen that my Mac mini is plugged into flick off then back on quickly. Usually just about a full second of black before it was back on. Now that I have unplugged and removed the Thunderbay from the circuit, this seems to have stopped!

I really hope this is something as simple as a diode or cap causing a ground issue.

 

[MrCheeto]

I uh...removed the power supply and used an external one. Everything worked but the symptoms are EXACTLY the same. It works for two minutes then just randomly disconnects here and there. I think I have safely ruled out power supply issues or ground related stuff.

Also, just to see if this is any issue with the power draw on the hard drives, I replaced them with SSD's. What I also notice is that ALL drives disconnect at the exact same time so it's not like a jolt on one or another drive, it's something shared by all four SATA ports.

Any clue what sort of tests I can do with an oscilloscope and a standard DMM?