Heat In Target Disk Mode

[kylepro88]

I have a 2017 iMac and 2017 MacBook Pro. Because I want to be on the go when I need to and immediately come home and hop to what I was doing on the iMac... without worrying about an external I lug/plug everywhere every time... without using a sync app like Dropbox... Target Disk Mode seemed like a solid option through the TB3 cable.

It's working great, but I'm noticing the laptop is fairly hot while being used in this way, and the fans even kick up and run at a modest but noticeable speed. Why would that be? I'm on my iMac right now with the MBP plugged in and connected and it's doing this, yet I'm not currently doing anything that's using the drive at all. The area above the 1-4 keys (typically very hot during a render) is very warm. It's not HOT but it's definitely heating up significantly.

Thunderbolt Bridge had similar speeds, so I might just try that for a few days and see if something similar happens. Any thoughts on the reason for heat? (the laptop is open fyi)

 

[chabig]

Computers use power (electricity) to do work. The byproduct of work is heat. Consider your car engine as an analogy. It gets warm even at idle, right? That's why the engineers built a cooling system into it. Your computer has one too. But even with the cooling system you'll feel heat. It's all normal.

 

[kylepro88]

LOL I realize it generates heat and why. I can't believe you just responded with all that. Come on man.

I'm simply saying I know my machine, I know when/why and in what circumstance it generates the kind of heat it does in normal use, but the heat it's generating while in Target Disk Mode is far too hot. I'm simply asking if anyone has an explanation as to why that might be the case. I currently have it on normally with TB Bridge utilized and not only is it quiet, it's cool.

Target Disk Mode offers it's own benefits, like being able to delete files without the "delete immediately" warning you get while connecting to another computer as a server vs. an HD like target disk mode, so I'de prefer to use Target Disk Mode ongoing, but the heat/noise concerns me a bit.

 

[iMacDragon]

Target disk mode seems to have always been implemented in an unefficient way somehow, I recall it getting hot even back in firewire days. I don't think the CPU properly idles whilst in TDM or something.

 

[chabig]

I'm simply saying I know my machine, I know when/why and in what circumstance it generates the kind of heat it does in normal use, but the heat it's generating while in Target Disk Mode is far too hot. I'm simply asking if anyone has an explanation as to why that might be the case.

I get a kick out of people who think they know better that Apple’s engineers how the machines should work. The machine isn’t running a full OS when it’s in target disk mode. I have to assume there is a reduced level of control/optimization, so it’s not surprising that it might not manage temperature the same way it does when running a full OS. But because it’s designed, built, and delivered with that feature you have to know it’s safe and working as it should.

 

[kylepro88]

I get a kick out of people who think they know better that Apple’s engineers how the machines should work. The machine isn’t running a full OS when it’s in target disk mode. I have to assume there is a reduced level of control/optimization, so it’s not surprising that it might not manage temperature the same way it does when running a full OS. But because it’s designed, built, and delivered with that feature you have to know it’s safe and working as it should.

I didn't say I knew better than anybody, I simply know what the machine normally does when on normally. It runs hotter in TDM than normal idle so you're probably right re: the optimization. Maybe they have no choice but to set a fan speed (or a tight range) and just keep it on... due to lack of software running.

That's honestly all I was asking. I hadn't thought of the lack of control available as a reason, I just found the heat to be pretty substantial, especially with the HD connected but not "busy" with anything at the time.

I've had it in TB Bridge mode since last evening and it runs much cooler/quieter so I guess utilizing TDM is a no-no going forward... at least for what I'm doing.

 

[Fishrrman]

My opinion only, and you didn't really ask, but...

It's not worth it to try and keep one's laptop "exactly like" one's desktop.

I let my desktop(s) be desktop(s).
I let my MacBook Pro(s) be... MacBook Pro(s).

That is to say, each one has "its own stuff" on it.
Each one has a different purpose, and I don't try to make them "all alike".

When traveling, take along a USB flashdrive or hard drive with the "desktop stuff" you might need to access.

Again, my opinion only.

 

[Lennyvalentin]

I guess utilizing TDM is a no-no going forward... at least for what I'm doing.

I would speculate and say that target disk mode is intended to get stuff off or onto the mac at one specific instance, and not to have it work passively as an external drive all the time because it would never be power efficient in that role anyway compared to an actual external drive. There's just way too much electronics with way too much performance. An external drive can typically run off of a USB port; a macbook won't, even if you enable all the power saving features in the world.

If you find that you often need to access your macbook's drive from another computer, consider networking them and copying the files that way instead.

 

[linzburke13]

Did you ever find a solution to this? I'm also running in Target Disk Mode, and notice my laptop will start blasting the fan. This thread was awhile ago, but figured worth a shot. Thanks!