Mac Studio Keeps Rebooting Itself

[Loren Risker]

Do have it set to “start up automatically after a power failure” in System Preferences / Energy Saver?

Perhaps shutting off the external drive trips that.

[Mads Nybo jørgensen]

I had similar issues with my Mac Mini, both where it would go to sleep when I didn’t wanted it to, and at other times starting up although having told it to go to sleep, and observed it doing so.

On the first issue, after ZERO help from Apple support and several calls later, I found that there in the settings was two different settings that contradicted one another. Guess that it is the same issue when it randomly boots itself up – can only suggest complete shut-down, and then switch off at the wall or pull the power lead out…

Atb
Mads

[Ken Bennett]

I discovered what was causing my Mac Studio to re-start itself after shut has been completed. I have 4 external Seagate storage drives connected. If I take any of these offline (storage drives donʻt need to be spinning all day when they arenʻt being accessed) and shut down, the Mac Studio will reboot itself and give me a notice about a shut down issue. If I leave them running, no problem. The Mac will shut down.

So, is there a way to tell Mac if I take any external drive offline to shut down when I ask it to?

[Mads Nybo jørgensen]

Hey Ken,

It sounds crazy that a Mac Studio that has been powered down, powers up to tell you what you already know.
Not least as my normal sequence, would always be to shut down the computer first to keep the integrity of the any database/software accessing those external drives. And, then power off the drives.
Times might have moved on, but surely there can be no good reason for a Mac Studio to, on its own, power itself up?
I would look in settings, maybe even the drive settings, to see if you can stop it from happening.

Atb
Mads

[Thomas Howard]

Possibly this rebooting is related to stripe unit size. Highlight all the disks you want in the RAID, then right click to select new volume, you’ll give it a name, format, and then continue, the next menu will ask for the stripe unit size. For the M1 Macs choose 64k instead of the default 16k.

[Joe Marler]

I have observed this problem when certain Thunderbolt arrays are plugged in, I begin a normal MacOS normal shutdown, then it reboots. Upon reboot it displays a kernel panic error log which sometimes refers to a shutdown I/O stall or (more recently) “Halt/Restart Timed Out @IOPlatformExpert.cpp:883”.

Unlike user-mode code where exceptions can crash that app, the involved code here is kernel mode, so it will crash the entire OS. Of course it’s in the process of shutting down anyway, but it might cause an ungraceful shutdown — I don’t know where in the overall shutdown sequence it happens.

Fortunately this source code is open source and examination of it indicates that within IOPlatformExpert.cpp it was attempting to get the machine name from the device tree using the key value gIODTModelKey. For some reason that returned a NULL value, it dereferenced that variable which caused a crash. I don’t know the underlying cause; maybe it’s interrogating all I/O devices as part of sending dismount or shutdown commands and some Thunderbolt I/O devices do not respond within the expected period. It would seem a bug in the MacOS code because IMO it should continue the MacOS shutdown and log an error, not crash.

I have several RAID arrays and it only happens on one of them, an OWC Thunderbay 4 Mini which contains 4 x 4TB Samsung EVO 870 SATA III SSDs. It is using regular AppleRAID not SoftRAID.

This is on an M1 Ultra Mac Studio running MacOS Monterey 12.6.2, but it also happened on my iMac Pro on several prior versions of MacOS. My workaround is manually dismount and unplug that Thunderbolt array before I shut down or reboot the machine.