M4 mini with external boot drive?

[toke lahti]

I've been waiting for the release of M5 mini and then upgrade from my mini2018.

But now I'm reconsidering.
Because I want run macOS from external drive, so I can buy the cheapest version.
At least Apps and homedir should be in external. Or at least most of them.

Does anybody run their mini like that?

I've just probably toasted my second external ssd with mini2018.
I suspect the lack of TRIM over usb-c.

I'm moving to use TB-NVME now, but I don't know if TRIM will work even with that?
Does it? Can it?

I finally took the bite and tried sudo trimforce enable.
It immediately corrupted the internal ssd.
Now I'm trying to re-install "emergency user" installation to that internal ssd.
I use 24/7 that external installation, I would have needed internal installation just to check that external ssd's health.
Since Apple does not offer way to read SMART data and you can't use SATSMART when booting from external.

If the macOS life from external boot will be as miserable with M4/5 mini than it is with mini2018, I think I will pass.
Key issues:

1. TRIM
2. SMART
3. Those with ThunderBolt drive

and those issues with:
A) mini M4
B) mini 2018

 

[Fishrrman]

Years ago -- during the days of platter-based and fusion drives -- I was an advocate of booting/running from an external SSD.

In fact, I ran my 2012 Mini that way, from the day I took it out of the box until I retired it.

But... no more.
It no longer makes sense.

These days, with the internal SSD "integrated" with the CPU and RAM "all together", you simply can't get the performance from an external drive that you can get from the internal one.

If you're waiting for the m5 Mini, get one that's adequately-equipped from the start.
That means plenty of RAM (32gb at least) and a good sized internal SSD (1tb or more).
Then you've got something that will run great today, and KEEP running great into the future.

But again, it just no longer makes sense to boot from an external drive.
I'm wondering if at some point, in a future OS upgrade, Apple might remove the ability to do this completely...

 

[turbineseaplane]

These days, with the internal SSD "integrated" with the CPU and RAM "all together", you simply can't get the performance from an external drive that you can get from the internal one.

This is simply not true.

In fact, the base Mini M4 (256) can actually run slightly faster off a Thunderbolt NVMe enclosure/dock when equipped with a good quality Gen4+ drive.

How do I know?
I was running mine this way and the external SSD was slightly faster than the internal base SSD.

 

[Corefile]

Your data is more important than the boot drive so recovering your data is the primary constraint. I would use the internal drive as just the boot drive and keep valuable data elsewhere.

 

[Ben J.]

My main concern with an external boot drive would be the fragile Thunderbolt connection. I agree with Corefile; keep the internal as bootdisk, and use external(s) as bulk file storage.

 

[LeVan]

I've been waiting for the release of M5 mini and then upgrade from my mini2018.

But now I'm reconsidering.
Because I want run macOS from external drive, so I can buy the cheapest version.
At least Apps and homedir should be in external. Or at least most of them.

Does anybody run their mini like that?

I've just probably toasted my second external ssd with mini2018.
I suspect the lack of TRIM over usb-c.

I'm moving to use TB-NVME now, but I don't know if TRIM will work even with that?
Does it? Can it?

I finally took the bite and tried sudo trimforce enable.
It immediately corrupted the internal ssd.
Now I'm trying to re-install "emergency user" installation to that internal ssd.
I use 24/7 that external installation, I would have needed internal installation just to check that external ssd's health.
Since Apple does not offer way to read SMART data and you can't use SATSMART when booting from external.

If the macOS life from external boot will be as miserable with M4/5 mini than it is with mini2018, I think I will pass.
Key issues:

1. TRIM
2. SMART
3. Those with ThunderBolt drive

and those issues with:
A) mini M4
B) mini 2018

There are 2 issues here; 1. using an external SSD to boot from, and 2. Getting Trim to work on an external disk.
As for 1. It is possible using a Thunderbolt drive connected to a Mac Mini M4 or M5 when they come out. And I have done it using the case and drive combination below, but I can't recommend it as it tends to corrupt the OS on the internal drive. 2. Trim will be enabled by default on a Thunderbolt drive running Sequoia or Tahoe.
I have been using 2 external Orico 2,5" drive cases with Crucial MX500 SSDs in them, connected to a MBA M2 and Trim is enabled with that combination. For a link to that drive case, do a Google search for Orico clear plastic 2,5" SSD case. USB devices will normally not have TRIM enabled, as it is only supported on a drive connected to a Thunderbolt port or an internal drive. However, if the UASP protocol is supported on the USB device, TRIM will work. The Crucial MX500 series has this UASP protocol enabled.
To check if UASP is enabled on a currently connected USB 3.1 device, use the following command using the Terminal;
Code:
log show --debug --last boot --predicate "processID == 0" | grep trim <--- can take a while, be patient.
To enable Trim:
Code:
sudo trimforce enable

 

[toke lahti]

My main concern with an external boot drive would be the fragile Thunderbolt connection. I agree with Corefile; keep the internal as bootdisk, and use external(s) as bulk file storage.

How can you control what is in internal?
Apps are easily over 100GB. So is Library.

 

[toke lahti]

Years ago -- during the days of platter-based and fusion drives -- I was an advocate of booting/running from an external SSD.

In fact, I ran my 2012 Mini that way, from the day I took it out of the box until I retired it.

But... no more.
It no longer makes sense.

These days, with the internal SSD "integrated" with the CPU and RAM "all together", you simply can't get the performance from an external drive that you can get from the internal one.

If you're waiting for the m5 Mini, get one that's adequately-equipped from the start.
That means plenty of RAM (32gb at least) and a good sized internal SSD (1tb or more).
Then you've got something that will run great today, and KEEP running great into the future.

But again, it just no longer makes sense to boot from an external drive.
I'm wondering if at some point, in a future OS upgrade, Apple might remove the ability to do this completely...

I can't fit ALL in 2TB internal and over that it just does no economical sense. Period.
If external has 80/120Gbit/s connection, I see no bottleneck in any kind of way.

Only problem is how well OS handles these things and well, Apple wants you to pay apple tax for the storage...

 

[toke lahti]

There are 2 issues here; 1. using an external SSD to boot from, and 2. Getting Trim to work on an external disk.
As for 1. It is possible using a Thunderbolt drive connected to a Mac Mini M4 or M5 when they come out. And I have done it using the case and drive combination below, but I can't recommend it as it tends to corrupt the OS on the internal drive. 2. Trim will be enabled by default on a Thunderbolt drive running Sequoia or Tahoe.
I have been using 2 external Orico 2,5" drive cases with Crucial MX500 SSDs in them, connected to a MBA M2 and Trim is enabled with that combination. For a link to that drive case, do a Google search for Orico clear plastic 2,5" SSD case. USB devices will normally not have TRIM enabled, as it is only supported on a drive connected to a Thunderbolt port or an internal drive. However, if the UASP protocol is supported on the USB device, TRIM will work. The Crucial MX500 series has this UASP protocol enabled.
To check if UASP is enabled on a currently connected USB 3.1 device, use the following command using the Terminal;
Code:
log show --debug --last boot --predicate "processID == 0" | grep trim <--- can take a while, be patient.
To enable Trim:
Code:
sudo trimforce enable

My StarTech's sata adapter has UASP. Doesn't help.
I also have Orico cases that they say that have UASP, but doesn't work with mini2018.
So, it is probably also about the mac. Macs have always been very picky about different usb controllers.

Amazing thing happened. I did run EtreCheck with my old install. It complained about system disk (evo 860) writing speed: 30MB/s!
Since I can't check SMART health with macOS when booted from external (thanks Apple!), I connected it to old windows laptop and checked the health with CrystalDiskInfo.
Then back to mac.
I hade to re-install internal ssd's OS, because trimforce enable corrupted it.
Write speed was doubled to 60MB/s!
But the OS was not run from it then.
I then booted back to my normal external install and, lo and behold, the write speed was over 400 MB/s.
At the same time free space went from previous 100GB to 192GB!

So I guess connecting it to Windows triggered TRIM!
Or maybe trimforce really worked?

Running that command gave me:

TokesMini2018:~ ext-toke$ log show --debug --last boot --predicate "processID == 0" | grep trim

2026-05-03 19:28:48.199190+0300 0x24b Default 0x0 0 0 kernel: (apfs) spaceman_scan_free_blocks:3374: disk3 scan took 0.314771 s (no trims)

2026-05-03 19:31:19.844457+0300 0x760 Default 0x0 0 0 kernel: (apfs) spaceman_scan_free_blocks:3374: disk1 scan took 0.004799 s (no trims)

2026-05-03 19:31:19.878848+0300 0x760 Default 0x0 0 0 kernel: (apfs) spaceman_scan_free_blocks:3356: disk1 scan took 0.034380 s, trims took 0.025537 s

2026-05-03 19:31:19.878858+0300 0x760 Default 0x0 0 0 kernel: (apfs) spaceman_scan_free_blocks:3366: disk1 7521434 blocks trimmed in 8579 extents (2 us/trim, 335943 trims/s)

2026-05-03 19:31:19.878863+0300 0x760 Default 0x0 0 0 kernel: (apfs) spaceman_scan_free_blocks:3369: disk1 trim distribution 1:1573 2+:1122 4+:4443 16+:802 64+:601 256+:38

2026-05-03 19:31:19.924378+0300 0x448 Default 0x0 0 0 kernel: (corecapture) 000155.677589 wlan0.A[158] [ik] IssueFwCap@6295: Unsupported bit flag[ 57], cap[ 'bcntrim' ] - EBT

2026-05-03 19:40:51.668527+0300 0x303 Default 0x0 0 0 kernel: (apfs) spaceman_scan_free_blocks:3356: disk3 scan took 724.308162 s, trims took 723.280380 s

2026-05-03 19:40:51.668624+0300 0x303 Default 0x0 0 0 kernel: (apfs) spaceman_scan_free_blocks:3366: disk3 45596417 blocks trimmed in 1198235 extents (603 us/trim, 1656 trims/s)

2026-05-03 19:40:51.668650+0300 0x303 Default 0x0 0 0 kernel: (apfs) spaceman_scan_free_blocks:3369: disk3 trim distribution 1:316791 2+:199049 4+:275959 16+:220544 64+:141981 256+:43911

2026-05-04 00:56:35.027636+0300 0x31a05 Default 0x0 0 0 kernel: (apfs) spaceman_scan_free_blocks:3374: disk5 scan took 0.052553 s (no trims)

2026-05-04 00:57:09.101163+0300 0x31a05 Default 0x0 0 0 kernel: (apfs) spaceman_scan_free_blocks:3356: disk5 scan took 34.073495 s, trims took 34.059448 s

2026-05-04 00:57:09.101195+0300 0x31a05 Default 0x0 0 0 kernel: (apfs) spaceman_scan_free_blocks:3366: disk5 481547372 blocks trimmed in 10345 extents (3292 us/trim, 303 trims/s)

2026-05-04 00:57:09.101198+0300 0x31a05 Default 0x0 0 0 kernel: (apfs) spaceman_scan_free_blocks:3369: disk5 trim distribution 1:3995 2+:2556 4+:3259 16+:163 64+:184 256+:188

My usb boot disk is disk2 and it's container is disk3.
My soon to be boot disk (tb-enclosure + nvme) is disk4+5.
Usb stick that I installed Sequoia to nvme is disk6.
Internal is disk0+1.

Thanx, thanx, thanx for the advice!

 

[gilby101]

My StarTech's sata adapter has UASP. Doesn't help.
I also have Orico cases that they say that have UASP, but doesn't work with mini2018.
So, it is probably also about the mac. Macs have always been very picky about different usb controllers.

macOS does not support/enable TRIM for USB 3.x without a driver from the vendor. E.g. Samsung provide a driver (kext) for Samsung USB3.x drives. I have TRIM for my Samsung T7 and T5. Note that it is the communication protocol (what the enclosure provides) plus macOS support which determines TRIM, not the drive type (nvme, SATA)

Out of the box, macOS only supports TRIM for Thunderbolt drives.

I hade to re-install internal ssd's OS, because trimforce enable corrupted it.

As you have discovered, don't use trimforce. It is at best a waste of effort.

log show --debug --last boot --predicate "processID == 0" | grep trim

I use this for the grep part: grep -e "blocks free in" -e "blocks trimmed". macOS does TRIM after startup. In my case, TRIMming of Samsung USB 3.x drives is 20 times slower than internal drive. But it makes a significant change to performance.

I am a bit surprised that your TB connected drive is so slow (303 trims/s) - something odd there.. My Samsung T7 is about the same speed as your external door disk (1656 trims/s). And my internal (in 2019 iMac) is so much faster though not a fast as yours.

My usb boot disk is disk2 and its container is disk3.

TRIMming takes place at the container (partition) level, not physical drive.

My usb boot disk is disk2 and it's container is disk3.

What is the enclosure for disk2+3? And is it USB 3.x? I don't think Windows could enable TRIM on macOS. Do you now have any 3rd party drivers installed which might account for the TRIM? Look with kextstat | grep -v apple

 

[gilby101]

Because I want run macOS from external drive, so I can buy the cheapest version.

I think that is a mistake if by that you mean 256 GB - you should get a 512 internal and use that for macOS and your home folder - move large folders to external and symlink from your user folder.

If you want a new Mini, Apple has forced your hand - the 256GB is discontinued.

 

[apostolosdt]

I can't see why you cannot; I've been doing that with all my Macs. Why? "Because I can!"

But I always watch some simple rules, like I run OS on ext SSD I trust, mostly T7. And the internal disk keeps the highest OS possible---just in case; also never keep my precious data on disk, only in the cloud.

Regarding your question about the Mini M4 in particular, that scheme has worked perfectly for me. So, do not hesitate to do the same. But... hurry up, for T7 prices have been going up pretty fast now.

 

[toke lahti]

macOS does not support/enable TRIM for USB 3.x without a driver from the vendor. E.g. Samsung provide a driver (kext) for Samsung USB3.x drives. I have TRIM for my Samsung T7 and T5. Note that it is the communication protocol (what the enclosure provides) plus macOS support which determines TRIM, not the drive type (nvme, SATA)

Can you point me the kext for my evo 860?
Google can't find it.

As you have discovered, don't use trimforce. It is at best a waste of effort.

Well, my macOS didn't TRIM my samsung boot drive. Now it does.
There's 2 possible explanations: either connecting to Windows triggered TRIM or using trimforce command.
Are you sure it was the former?

I am a bit surprised that your TB connected drive is so slow (303 trims/s) - something odd there.. My Samsung T7 is about the same speed as your external door disk (1656 trims/s). And my internal (in 2019 iMac) is so much faster though not a fast as yours.

My nvme (Mushkin) has not been used anything more than one install of OS.
Could it be that it is slow to trim, because there is so little to trim?

How trim speed is relevant to boot disk's ”snappiness" as running OS?

What is the enclosure for disk2+3? And is it USB 3.x? I don't think Windows could enable TRIM on macOS. Do you now have any 3rd party drivers installed which might account for the TRIM? Look with kextstat | grep -v apple

There is no enclosure. Adapter is this: https://www.amazon.de/dp/B0133F30R8/ref=pe_27091401_487027711_TE_SCE_dp_i1.

I seem to have an old lacie mvumi kext, but I guess it has nothing to do with why suddenly NOW my boot drive gets trimmed?

 

[throAU]

Years ago -- during the days of platter-based and fusion drives -- I was an advocate of booting/running from an external SSD.

In fact, I ran my 2012 Mini that way, from the day I took it out of the box until I retired it.

But... no more.
It no longer makes sense.

These days, with the internal SSD "integrated" with the CPU and RAM "all together", you simply can't get the performance from an external drive that you can get from the internal one.

If you're waiting for the m5 Mini, get one that's adequately-equipped from the start.
That means plenty of RAM (32gb at least) and a good sized internal SSD (1tb or more).
Then you've got something that will run great today, and KEEP running great into the future.

But again, it just no longer makes sense to boot from an external drive.
I'm wondering if at some point, in a future OS upgrade, Apple might remove the ability to do this completely...

This.

Stop being QUITE so tight fisted and avoid making dumb decisions from before purchasing the thing.

 

[toke lahti]

I think that is a mistake if by that you mean 256 GB - you should get a 512 internal and use that for macOS and your home folder - move large folders to external and symlink from your user folder.

If you want a new Mini, Apple has forced your hand - the 256GB is discontinued.

I don't mind paying for 512GB.
But my home folder is 2TB.
I can of course move music and photos away, but there is still Apps and Library.
That would get tight very soon.
I have been forced to do that jiggle for some yers now, but I think computers should do that automatically.
Some developers at Apple thought so too and invented Fusion Drive. Best thing since Time Machine.
And of course they had to axe it. To get more apple tax.

I have no issues of little slower OS, if Apple just made the OS work well from external.
Or invent the wheel once more: desktop computer that has easily swappable internal storage.
Would be so easy to shring classic Mp to size of studio+mini. With 4 blade slots or even more.

Also because we have these ultra fast interconnecions like tb5, why not to take maximal benefit from them?
Only reason seem to be apple tax.

 

[throAU]

Set yourself up to work from internal storage for active projects, and a NAS or iCloud of archive of completed work.

Security is a concern, the internal storage is much more difficult to mess with as an attacker.

 

[toke lahti]

This.

Stop being QUITE so tight fisted and avoid making dumb decisions from before purchasing the thing.

When storage prices are now many times higher than last year, the sane choise would of course be Fusion drive: small fast ssd + big cheap slow ssd. Or even spinning platter.

 

[throAU]

When storage prices are now many times higher than last year, the sane choise would of course be Fusion drive: small fast ssd + big cheap slow ssd. Or even spinning platter.

uh... fusion drives/other hybrid SSD/hard drive solutions were crap

hard drive prices have exploded in the past few months too anyway. to get 4x 8TB 3.5" drives for my NAS I'm looking at $2k AUD... ridiculous.

 

[toke lahti]

Set yourself up to work from internal storage for active projects, and a NAS or iCloud of archive of completed work.

My folders now:
/Apps 123GB
/System 19GB
/Lib 21GB
~/Lib 247GB
~/Doc 90GB

On the other disk:
Pics 494GB
Music 309GB
Movies 556Gb.
~20TB stuff elsewhere.

And I don't really do any work with my mac.
I did quite a bit video editin back in time, things would be very different if I still woul do it with my next mini.

So no, this is not about "projects". This is my personal digital footprint.
In Finnish language "computing" was called in history as ATK, meaning "automatic data handling".
That's what I would like to have with the most advanced OS in the world without breaking the bank.
Yes, I'm quite poor.

 

[toke lahti]

uh... fusion drives/other hybrid SSD/hard drive solutions were crap

hard drive prices have exploded in the past few months too anyway. to get 4x 8TB 3.5" drives for my NAS I'm looking at $2k AUD... ridiculous.

They were not crap.
If ssd would break, it would do it in Fusin drive as well as standalone.

I have had more broken ssd's than hdd's, when balanced with terabytes and years.

 

[toke lahti]

My main concern with an external boot drive would be the fragile Thunderbolt connection. I agree with Corefile; keep the internal as bootdisk, and use external(s) as bulk file storage.

This is about desktop enviroment.
I have tripped on two cables in my lifetime at home.
My av receiver has a flimsy hdmi connector because of that.
Tb cables are so short that I won’t trip on them.

 

[toke lahti]

macOS does not support/enable TRIM for USB 3.x without a driver from the vendor. E.g. Samsung provide a driver (kext) for Samsung USB3.x drives. I have TRIM for my Samsung T7 and T5. Note that it is the communication protocol (what the enclosure provides) plus macOS support which determines TRIM, not the drive type (nvme, SATA)

I was stupid enough to install that Samsung Magician. Same thing than with SATSMART driver: endless bootloops and finally OS banns all 3rd party kexts. Wasted another hour. Bootloop is not even automatic, you have to push mini on from power switch every time.
EDIT: This time this is worse. Still booting here.
Deleting both Samsung kexts didn't help. It has broken off something else on the way. Nice.

For the last decade, in macOS, you can’t use storage related kexts when booting from external.

Out of the box, macOS only supports TRIM for Thunderbolt drives.

Hopefully this will work with new installation.
I’ll wait for few days if more info appears on MA and then proceed…

 

[LeVan]

macOS does not support/enable TRIM for USB 3.x without a driver from the vendor. E.g. Samsung provide a driver (kext) for Samsung USB3.x drives. (and in the post above🙂 "Out of the box, macOS only supports TRIM for Thunderbolt drives."

I do not think this is correct. I have tested an Orico 2.5" USB 3.1 enclosure with a Crucial MX500 SSD inside, and Trim is enabled and works after running the "sudo trimforce enable" Terminal command.
I have read (on MacRumors) that even without installing any vendor-based driver, if the UASP protocol is supported on the USB device, TRIM will work. As mentioned, Trim is conducted on a reboot.
The Crucial MX500 series has this UASP protocol enabled. In the past, I used an Silicon Power SSD in the same Orico enclosure, and it became unusable after a very short time, even with the Trimforce command enabled. Obviously that device didn't support the UASP protocol. Not sure about other SP devices, but that one did not support Trim, at least using it with the hardware I have, macOS on a MBA M2. Thus, from my experience, whether or not Trim will work depends on the hardware device. Some devices like the Samsung drives seem to need a driver installed, (gilby101's experience) but SSD drives in the Crucial MX500 series at least do not need a driver. I have used the two Crucial drives I have for at least 2, and maybe 3 years now, and there has been only a minimum of speed reduction over that time period (maybe 3-5%?). The one SP SSD I tried went from over 400Mbs to 60-70Mbs (not sure about that unit, may be mbs) in a relatively short time period.

 

[throAU]

They were not crap.
If ssd would break, it would do it in Fusin drive as well as standalone.

I have had more broken ssd's than hdd's, when balanced with terabytes and years.

I never said anything about them breaking.

 

[gilby101]

Can you point me the kext for my evo 860

It depends on the enclosure/adapter which is what does the USB connection.

My folders now:
/Apps 123GB
/System 19GB
/Lib 21GB
~/Lib 247GB
~/Doc 90GB

The 90GB should be easy to move and add symlink in ~/

The 247GB needs some analysis. DaisyDisk is best. I am sure that some of it could be deleted (e.g. caches) or move to another disk (e.g. folders within ~/Library/Application Support)

I have read (on MacRumors) that even without installing any vendor-based driver, if the UASP protocol is supported on the USB device, TRIM will work.

Do you have a link for this?