Long Boot from external; internal boot is fast?

[kent5]

Hello all,
I've got a 2018 Mac mini (i5/32GB/256GB) with a curious thing happening at boot time.

My question stems from the boot process duration:
-When I boot from the internal drive, boot time is consistently around 20 seconds.
-When I boot from the external drive (2TB NVME, USB-C connected), the boot time is around 2 mins 20 seconds.
-During external boot, the progress thermometer gets to about the 25% mark, and seems to hang there for a long time.

I've tried booting from other external NVME drives, also USB-C connected, with similar results.
All drives are running new installs of Sonoma 14.3 and formatted APFS.
When the externals are used for large file transfers (multiple GB in size), it seems like the transfer speeds are pretty fast.
Once the Mac has completed booting from the external, it *seems* to operate about as fast as when booted from the internal.

Any guesses as to why the great discrepancy in boot times?

 

[waw74]

get black magic disk speed test, it's in the app store
compare the read/write speeds between the internal and external.

 

[kent5]

Thanks waw74 -- using that app was very enlightening.
Internal 1300r/2300w
External: 950r/950w

Do you think that it is that the externals are just limited to the speed of the Mac Mini 2018 lightning ports or is it my USB3 drive cables/mounts that are limiting it?

 

[Fishrrman]

I have a 2018 Mini that has Mojave on the internal SSD.

However, I have a copy of Sonoma on an external 2.5" SATA SSD in a USB3.1 gen2 enclosure.

I've noticed that booting from the external DOES take somewhat longer, specifically with Sonoma.
If you watch the "progress bar" at the bottom of the boot screen, it seems to "lag" for a while, then gets to around "the 50%" point, then speeds up to finish.

So... you're not the only one seeing longer boot times.
The slower speed of the external SSD vs the internal SSD probably has some impact.
But it seems like there are "other factors" with the boot process that -- at least with Apple's latest OS releases -- causes them to boot more slowly from an external drive.

 

[kent5]

@Fishrrman I was thinking the same thing. Yes, the external is slower, but it doesn't seem like that it would be sufficiently slower to extend boot times by a factor of 10.