Drives don't connect when plugging in the T4 cables

We have not seen any issues like this since Thunderbolt 2 days. Must be a cable that is not tight, or something. Thunderbolt 4 is generally pretty solid. Do you have any docks in your connections? How many enclosures/devices are in the chain?

Posted by: @softraid-support

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We have not seen any issues like this since Thunderbolt 2 days. Must be a cable that is not tight, or something. Thunderbolt 4 is generally pretty solid. Do you have any docks in your connections? How many enclosures/devices are in the chain?

Yes. I have your OWC Dock in the chain and two OWC enclosures. See description details.

I had done troubleshooting and the errors are repeatable in the past reports as to some portion of the RAID failing and also some portion of the RAID not logging on when plugged in while computer is booted. The only consistent fix is a full Restart. That resolves the issues.

Expect to be able to plug in a single T4 connection to a laptop computer and have everything show up, don't you think this a reasonable expectation? That hasn't happened in years - on two different computer (both MBP, the latest the newest MBP2024 M4 MAX). Why not?

@henry-in-florida 

Absolutely. If you have a T4 dock, it should be able to handle mounting all attached devices. What ever is going on is hardware caused. Let me ask around for any insight I may not have.

@henry-in-florida 
What is the model number of your dock?

@henry-in-florida 

One advice says take half the units and connect them to the other side of the laptop and try that for stability. See if you get reliability that way. It will give some info.

Posted by: @softraid-support

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@henry-in-florida 
What is the model number of your dock?

@SoftRAID Support I misspoke it is a Hub (OWC T4 Hub, OWCTB4HUB5P), the drive enclosures of the SATA SSD's are two Thunderbay 4 Mini.

Posted by: @softraid-support

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@henry-in-florida 

One advice says take half the units and connect them to the other side of the laptop and try that for stability. See if you get reliability that way. It will give some info.

Will try to dig up another longer cable to test with the split instead of daisy-chain. BTW, I've long complained about SAT RAID speed, but that is another issue, maybe not - a part of the same?

Posted by: @softraid-support

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@henry-in-florida 

One advice says take half the units and connect them to the other side of the laptop and try that for stability. See if you get reliability that way. It will give some info.

@softraid support

So, I split the two enclosures with separate cables, one through the OWC (normal connection) Hub, the other straight to an open port on the MBP. Success! Tried to unmount drives>disconnect both cables>reattach both cables. The sequence does not fail as previously. So is it the jumper cable or the secondary port on one or the other enclosure? I suspect the latter but cannot prove which jumper port (or cable) it might be. ANY IDEAS?

As to the secondary issue of speed of the RAID 4 (SATA) array... That sadly, was still disappointing. Attaching some screen shots. AJA displays error rate issues and severe slowdowns after 2min of running at any settings in AJA Speed Test. This might be unrelated to the first problem and one of long standing. 

Your hardware folks at OWC say that there may be a "timing issue"with drives in a RAID array housed in two separated enclosures, daisy chained together. I don't see how this is possible when they work just fine when hooked up with separate cables and same config... Do you?

@henry-in-florida 

First, with AJA, you must make these settings:
Set resolution to 8K video, Codec to 16bitRGBA, and filesize to 64GB.
Next, in settings, check "Dual DMA engine".

You can make it continuous. If you get some slowdown here, then yes there is an issue.

There could be a hardware issue (bad port/cable, etc), but there is no "interference" that would cause what you are seeing!

Posted by: @henry-in-florida

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Posted by: @softraid-support

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@henry-in-florida 

One advice says take half the units and connect them to the other side of the laptop and try that for stability. See if you get reliability that way. It will give some info.

@softraid support

So, I split the two enclosures with separate cables, one through the OWC (normal connection) Hub, the other straight to an open port on the MBP. Success! Tried to unmount drives>disconnect both cables>reattach both cables. The sequence does not fail as previously. So is it the jumper cable or the secondary port on one or the other enclosure? I suspect the latter but cannot prove which jumper port (or cable) it might be. ANY IDEAS?

Attachment : Screenshot 2025-09-17 at 09.35.42.png

 

So I'm at a a loss right now, to diagnose this connectivity issue any further and do suspect rather strongly that it's likewise tied into a performance issue, too. I have swapped out cables and connectors on the back of these two 5YO enclosure and from wha they tell me in the HDW area of OWC, the drive is now considered obsolete and no one has ever complained about this as a problem (huh? I've been complaining about it as a SFW issues on these pages for years!). Nobody here has set me straight that it might be HDW. 

I'd like OWC to upgrade my HDW in the case of some rumored "timing problems" affecting these OWC products so the problem goes away. Otherwise I'm inclined to ditch this whole exercise for something that give both better connectivity (no dropped RAID drives) and proper performance in terms described - repeated runs slowing down to a crawl in write performance. This is not good and rapidly becoming unaffordable to continue the nightmare. 

@henry-in-florida 

I only see an older support file from you. I can try to reproduce your hardware, just so you have a sanity check. I do not forsee any issues, though.

You have the 4M2, then 2 Thunderbay 4 drive (SSD) enclosures, right?

I can try to play around and see if I get anything like what you are, but I don't think I will.

Did you try both ports on the last device in the chain?

Posted by: @softraid-support

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@henry-in-florida 

I only see an older support file from you. I can try to reproduce your hardware, just so you have a sanity check. I do not forsee any issues, though.

You have the 4M2, then 2 Thunderbay 4 drive (SSD) enclosures, right?

I can try to play around and see if I get anything like what you are, but I don't think I will.

Did you try both ports on the last device in the chain?

 

@SoftRAID Support,

It seems to me that your OWC departments do not communicate well. I sent OWC Support my support file assuming a HDW fault. They did not recognize any previous cases at your forums and have no apparent interest in helping me there on the old no longer supported hardware. I enclose the same file sent to them and would appreciate any new findings at your end. referrals to you that they attempted to you (Rufus) failed and he never called me back. 

To your questions, yes I tried both ports and swapped cables around in order to try replicating the issue proving one or the other drive bay as a culprit for the daisy-chain effect. Both do the same effect at the end of the chain - fail to recognize parts of the RAID Array when plugged in to my Mac cold. And then when a separate cable set up is used either enclosure on the separate cable by itself with other devices on the existing set up work properly, logging on ALL RAID drives fully at the outset (some do take a bit more time to show up than others though, but when they do there is no problem with "missing drives" in the array. 

Your further questions about my Mac Hardware are posted in my signature line below which I keep updated with current software in my profile. It's at the end of every post I send you! 

The questions I'm trying to find answers to with my two enclosure set up (all 8 with populated SATA SSD mostly Samsung, one WD, 500GB RAID plus several independent volumes) is:

1. Why missing drives errors in several RAID and Standalone volumes when plugged into when daisy-chained to a single Mac Port? 
2. Why it works perfectly, repeatably with two cables plugged in simulataneously instead of a short daisy-cord between the enclosures (vs. a single cable)? 
3. Why the Speed Test slowdowns after two+ minutes specifically on Write Performance (800MBs ->80MBs or less)?
4. Why error rates come and go as shown on my screenshots? 
5. Can you recreate my finding there in a similar way? NB, the same problem has tormented me on my previous MBP 2021 M1 with the same complement of externals. 

For your reference the case at "OWC Support Team" is 02868643. If you would like a copy of their emails about the issue, I can send off line. Contact me by email. A disappointing experience, many I say. Feel free to edit this, but color me disappointed!