Boot from external TB3 SSD on 2018 Mini?

weezin

macrumors regular
Original poster
Jul 20, 2012
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I have a chance to buy a used 2018 Mac Mini at an astonishingly good price, but the catch is that it only has the 128gb hard drive (I need at least 500).

That got me thinking - should I get the Mini, but some TB3 estrnal SSD and boot off of that?

Is that a terrible idea (will I sacrifice a lot of speed, etc)? If so, why? If not, which drives should I be looking at?
 

Ledgem

macrumors 68000
Jan 18, 2008
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Hawaii, USA
Yes, you can do it, and no, it's not a terrible idea. I don't have the 2018 mini and thus I'm not sure how its SSD compares, but compared with systems even from 2017, add-in SSDs through Thunderbolt 3 offered superior performance to Apple's built-in SSDs. The technology has come a long way and evidently Apple isn't doing its best to keep up.

The popular model at the moment is the Samsung X5, which comes in a variety of storage capacities, all of which are cheaper than what you can get through Apple. However, you could theoretically get any NVMe-type SSD and a NVMe-Thunderbolt 3 enclosure, and then work with that.
 

weezin

macrumors regular
Original poster
Jul 20, 2012
168
44
Yes, you can do it, and no, it's not a terrible idea. I don't have the 2018 mini and thus I'm not sure how its SSD compares, but compared with systems even from 2017, add-in SSDs through Thunderbolt 3 offered superior performance to Apple's built-in SSDs. The technology has come a long way and evidently Apple isn't doing its best to keep up.

The popular model at the moment is the Samsung X5, which comes in a variety of storage capacities, all of which are cheaper than what you can get through Apple. However, you could theoretically get any NVMe-type SSD and a NVMe-Thunderbolt 3 enclosure, and then work with that.
Thanks!

Reading now about USB 3 Gen 2 and Thunderbolt 3 differences. the USB versions are obviously cheaper and I'm wondering if that might be an okay route to go (for now).

Was considering the Pluggable enclosure with a 500GB Crucial P1. That would save me about $100 over a Samsung X5. Would love the faster speeds (I think? Would I even notice?) but not sure the price differential makes sense for me right now.

I'm upgrading from a 2011 iMac with an SSD, so I think either option probably blows that one out of the water!
 

Fishrrman

macrumors P6
Feb 20, 2009
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5,554
I agree with what Stephen R wrote above.
128gb will do fine ... IF you relegate it to holding only:
- OS
- applications
- "basic" home folders.
Leave "the rest of the space" empty, for swap and temp files, etc. Keep it "lean and clean".

You can get an external USB3 SSD for storage of the "large libraries" that might otherwise reside in your home folder, such as:
- Pictures (Photos library, or libraries for other editing apps)
- Music (iTunes music folder, and other music)
- Movies (Projects for iMovie, Final Cut, ect.)

That's one way to do it.

Another way:
Get a Samsung X5 thunderbolt3 drive (as distinguished from the t5 USB3 drive).
It will run as fast as the Mini's internal SSD.
But... relatively expensive, vis-a-vis the "first option" above.
 
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weezin

macrumors regular
Original poster
Jul 20, 2012
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44
Thanks guys! Since posting, I figured my plan was to put the "home" folders on the external and leave the OS and applications on the internal. I also ordered a pluggable USB M.2 enclosure and a Crucial P1 NVMe 500gb.

Do I set that up using THIS method? Ideally, I'd love to it to "look" like the entire home folder is on the same drive, even if parts of it are on an external. It seems like this method will do that.
 

Fishrrman

macrumors P6
Feb 20, 2009
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weezin wrote:
"Since posting, I figured my plan was to put the "home" folders on the external and leave the OS and applications on the internal."

NO!
Don't attempt to do this unless you are absolutely sure you know what you're doing!
It can cause all kinds of problems.
 

Stephen.R

macrumors 65816
Nov 2, 2018
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Thailand
I agree with @Fishrrman on that. Unless you specifically need your home folder to be elsewhere (ie you have a lot of iCloud Drive data and don’t want to use “optimise storage”) just put data you use on the external. iTunes and Photos “library” content can all be located elsewhere outside your home folder.

My understanding is that it’s (relocating your home folder) a lot less fraught with peril than it used to be but I’d still opt for other solutions first.
 

weezin

macrumors regular
Original poster
Jul 20, 2012
168
44
weezin wrote:
"Since posting, I figured my plan was to put the "home" folders on the external and leave the OS and applications on the internal."

NO!
Don't attempt to do this unless you are absolutely sure you know what you're doing!
It can cause all kinds of problems.
I agree with @Fishrrman on that. Unless you specifically need your home folder to be elsewhere (ie you have a lot of iCloud Drive data and don’t want to use “optimise storage”) just put data you use on the external. iTunes and Photos “library” content can all be located elsewhere outside your home folder.

My understanding is that it’s (relocating your home folder) a lot less fraught with peril than it used to be but I’d still opt for other solutions first.
Okay, I've seen that methodology recommended on other threads in MR. What kinds of problems might you run into with this?

The problem is that I am moving to a 128gb drive from a 500gb one, where I am currently taking up 455gb.

Oddly, my home folder shows 381gb of space taken, but when I add up the sizes of all of the folders in it, I only get 183gb...

Ideally, I'd either boot from another drive entirely, or boot from the internal drive and have most of my data on an external drive. In my mind, that would be things like Music, Photos, Movies, Dropbox, Downloads, Box, etc. Applications would stay in the internal drive.

Would that work or are there problems with that?
 

Beliblis

macrumors regular
Dec 31, 2011
188
5
I'm thinking about doing the same: purchase 128gb SSD MacMini from Apple, and attach external 500gb or 1TB X5 SSD. One reason is price, the other is: wearing out the internal drive. (I tend to use my computers for many years – current system is MacMini 2012).

I'd definitely use the external SSD as the main System drive with all home folders.

Question is: what to use the internal SSD for. Maybe as a swap drive for Photoshop? Or would that wear out the drive too quickly? (I know I may be over-cautious here, but SSDs do wear out, and I'll probably work with this machine for 5-7 years).

The fact that the SSD is soldered on really annoys me. I mean – what happens when the internal SSD dies? Can the MacMini still be booted from the external SSD? Or would the power-up process somehow recognise that something's broken?
 

handheldgames

macrumors 68000
Apr 4, 2009
1,697
915
Pacific NW, USA
Okay, I've seen that methodology recommended on other threads in MR. What kinds of problems might you run into with this?

The problem is that I am moving to a 128gb drive from a 500gb one, where I am currently taking up 455gb.

Oddly, my home folder shows 381gb of space taken, but when I add up the sizes of all of the folders in it, I only get 183gb...

Ideally, I'd either boot from another drive entirely, or boot from the internal drive and have most of my data on an external drive. In my mind, that would be things like Music, Photos, Movies, Dropbox, Downloads, Box, etc. Applications would stay in the internal drive.

Would that work or are there problems with that?
Running macOS from a 128GB SSD is challenging to say the least. When in this situation, my user folder resided on the boot drive and was managed by the OS, folders to documents, downloads, music, photos, etc were all symbolic links to other data drives. I also symbolically linked and relocated some of the apple developer folders that quickly bloated the os. This approach works well with time machine as long as all the drives are backed up. The only elements on the SSD were basically what the OS needed to run. User data and content was stored elsewhere.

So yes, it can be done. There are safe ways to approach it. Always have a backup in case something goes wrong.

The 2nd biggest downside of the 128GB drive is it's performance. The 1st being having to work around the limited size.
 

EightyTwenty

macrumors 6502a
Mar 11, 2015
766
1,552
I'm thinking about doing the same: purchase 128gb SSD MacMini from Apple, and attach external 500gb or 1TB X5 SSD. One reason is price, the other is: wearing out the internal drive. (I tend to use my computers for many years – current system is MacMini 2012).

I'd definitely use the external SSD as the main System drive with all home folders.

Question is: what to use the internal SSD for. Maybe as a swap drive for Photoshop? Or would that wear out the drive too quickly? (I know I may be over-cautious here, but SSDs do wear out, and I'll probably work with this machine for 5-7 years).

The fact that the SSD is soldered on really annoys me. I mean – what happens when the internal SSD dies? Can the MacMini still be booted from the external SSD? Or would the power-up process somehow recognise that something's broken?
You will not wear out the internal drive.
 

Fishrrman

macrumors P6
Feb 20, 2009
17,209
5,554
handheld wrote:
"Running macOS from a 128GB SSD is challenging to say the least"

No.
It's not.
I boot and run a copy of Mojave from a 128gb SSD with absolutely NO problems at all.

WHY?
Because I don't have a lot of junk in my home folder.
Just checked and that drive has 63+gb of space used, the rest is still free.
 

handheldgames

macrumors 68000
Apr 4, 2009
1,697
915
Pacific NW, USA
handheld wrote:
"Running macOS from a 128GB SSD is challenging to say the least"

No.
It's not.
I boot and run a copy of Mojave from a 128gb SSD with absolutely NO problems at all.

WHY?
Because I don't have a lot of junk in my home folder.
Just checked and that drive has 63+gb of space used, the rest is still free.
GREAT!! Nice to hear it works in your situation. Storage utilization depends on ones data set, workflow and diligent file management practices . I was merely offering a way for users to offload specific folders without the need to worry about using up the remaining +/-50GB of storage.

When using a PCIe 128GB SSD boot disk back in 2013, because it was the only drive publicly available, I ended up using GrandPerspective on a regular basis to identify the buildup of unnecessary crud that would end up clogging the OS. It's one of the few tools that provides a great visual interface for finding left over digital cruft that's no longer needed.

FWIW... From what I went through back then, I would never consider purchasing any type of Mac with a 128GB SSD today. Compared to a 512GB or 1TB SSD, they are just too slow and too small.
 
Last edited:

michaelb5000

macrumors regular
Sep 23, 2015
107
55
I am not sure of what problems I should be worried about, but I have a 128 mini and have all of my home folders on an external drive. It works fine and I like it better that way. I have also in the past done it the other way. But I like backing up my entire user files in one shot, including onto old drives that I keep at work once or twice a year. Harder to do if your home directories are scattered.
 

smetvid

macrumors 6502
Nov 1, 2009
412
155
I bought a 128GB Mac Mini as well and with all my apps installed I am using about 70GB of it. I keep all my content like iTunes, photos, books, documents and projects on an external drive. 128GB is plenty of space as long as you keep content on an external drive. If you think about it music, PDF documents, books and jpeg images are pretty darn small and really don't even come close to needing the speed of even a basic SSD. Raw photos can see a small advantage to faster storage but even those don't really need it. I edit professional 4k video from a Panasonic GH4 off of a desktop 7200 RPM HDD. I also develop mobile apps, edit raw photos and create various graphic, web, UX and print design projects with that same drive and it really doesn't hold me back much. Even moving to a 500 MB/s SSD would likely give me all the benefits I would ever see from that content. Moving to m2 storage via USB3.1 at up to 1,200 Mb/s would definitely provide all the benefits faster speed could ever provide with that content. We are talking a couple of milliseconds difference with smaller files if any difference at all.

A boot drive makes sense to be as fast as possible because applications are made up of hundreds or thousands of tiny files. The boot drive is also constantly accessed as you do things in those applications. Once a project is open it doesn't touch the storage again until you save. In the case of FCPX it constantly saves to the storage so thats a unique case but a FCPX project is also a small text file. The boot drive can also use a swap file when you run out of Ram. Having 3,000 MB/s flash storage vs a 160 MB HDD will make a massive impact on the speed of that swap file. Even compared to a 500 MB/s SSD drive thats a 6x speed increase as a virtual form of Ram which helps a ton.

Other reason I did this is I have multiple Macs and I wanted to be able to bring my library of content with me no matter where I go.

I stopped buying large drives in my Macs once I realized I was never using more than 80GB in each of them. This is due to keep all content on an external drive to move between Macs. That extra internal storage now just sits there unused.
 

1080p

macrumors 68030
Mar 17, 2010
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Planet Earth
I was thinking of doing this exact same thing on a newly acquired 2018 Mac Mini. Would there be any issue using all of the 128GB internal drive for Bootcamp while keeping MacOS on a TB external drive?
 

Ledgem

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Jan 18, 2008
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Hawaii, USA
A boot drive makes sense to be as fast as possible because applications are made up of hundreds or thousands of tiny files. The boot drive is also constantly accessed as you do things in those applications. Once a project is open it doesn't touch the storage again until you save. In the case of FCPX it constantly saves to the storage so thats a unique case but a FCPX project is also a small text file. The boot drive can also use a swap file when you run out of Ram. Having 3,000 MB/s flash storage vs a 160 MB HDD will make a massive impact on the speed of that swap file. Even compared to a 500 MB/s SSD drive thats a 6x speed increase as a virtual form of Ram which helps a ton.

...

I stopped buying large drives in my Macs once I realized I was never using more than 80GB in each of them. This is due to keep all content on an external drive to move between Macs. That extra internal storage now just sits there unused.
If the goal is speed, then a larger SSD still makes sense. I can't find data on the latest SSDs, but it used to be that larger SSDs could perform twice as many read/write operations as smaller SSDs. Raw transfer speeds aren't quite as dramatic but larger drives still have the edge.

SSDs are still much faster than standard HDDs, but if you're sticking with 128 GB SSDs, you're getting the slowest of the SSD performance.
 

nicho

macrumors 68030
Feb 15, 2008
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If the goal is speed, then a larger SSD still makes sense. I can't find data on the latest SSDs, but it used to be that larger SSDs could perform twice as many read/write operations as smaller SSDs. Raw transfer speeds aren't quite as dramatic but larger drives still have the edge.

SSDs are still much faster than standard HDDs, but if you're sticking with 128 GB SSDs, you're getting the slowest of the SSD performance.
here are a couple of tests i just did:

2018 mac mini (256GB SSD)
Internal.png

Samsung X5 (500GB) over thunderbolt 3, connected to same mac mini
SamsungX5.png
 

Fishrrman

macrumors P6
Feb 20, 2009
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Interesting numbers in #19 above.

The read speeds are all-but equal.

But the X5 has write speeds that are about 50% faster than the internal Apple SSD.
 

Stephen.R

macrumors 65816
Nov 2, 2018
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From memory the speeds (read, specifically I think?) of internal SSD on a 2018 Mac mini, from 128 > 256 > 512 roughly double at each step, but after 512 the increase with capacity drops off. I may be remembering the amount of increase incorrectly (it may not be double) but 512 was definitely where you face rapidly diminishing returns in terms of speed (this is the exact reason I ordered by Mini with 512GB)
 

smetvid

macrumors 6502
Nov 1, 2009
412
155
If the goal is speed, then a larger SSD still makes sense. I can't find data on the latest SSDs, but it used to be that larger SSDs could perform twice as many read/write operations as smaller SSDs. Raw transfer speeds aren't quite as dramatic but larger drives still have the edge.

SSDs are still much faster than standard HDDs, but if you're sticking with 128 GB SSDs, you're getting the slowest of the SSD performance.
That may be true but even the 128GB is still faster than a SATA SSD drive or one connected via USB3. It is typically the write speed that suffers more than the read speed and most people tend to read files vs write them. For example video editing typically involves 100% read activity until one is ready to hit render. Same is true for editing raw photos that are already on the drive. Editing a photo involves reading that data and manipulating that data on the fly. Write only happens once finished and hitting save or export.

But I do agree with you that if one absolutely must have 3,000 Mb/s write speed and feels as though their computer sucks without having that then they should go with a 512GB drive. 512GB is also a good size for those that do want to keep their music and documents on the internal drive. Photos can get a bit large however so I would still suggest moving those to an external drive.

When it comes to speed however I doubt 1,200 MB/s vs 3,000 MB/s would make a huge impact on day to day use. Thats still really fast. Now in terms of a swap file when all the Ram is used up that speed could have an impact and I would probably go with the 512GB if one doesn't upgrade the Ram as well.

For performance 16GB and a 512GB SSD is likely the sweet spot. Most users will rarely go over 16GB of Ram and if they do that ultra fast 512GB SSD should pick up the slack very nicely. Since my Mac Mini has 32GB in it and I can upgrade that to 64GB someday I'm less concerned about swap file size since I can add affordable Ram. I really just need 128GB to boot up the system and apps which is mostly a read process.
 

Ledgem

macrumors 68000
Jan 18, 2008
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When it comes to speed however I doubt 1,200 MB/s vs 3,000 MB/s would make a huge impact on day to day use. Thats still really fast. Now in terms of a swap file when all the Ram is used up that speed could have an impact and I would probably go with the 512GB if one doesn't upgrade the Ram as well.
The speed numbers being quoted represent sequential read/write speeds, which apply to some of the use cases you're discussing. They're important, but not as important as random read/write speeds, and IOPS (input/output operations per second). Those are the factors that impact how responsive a system feels. Booting your computer involves accessing a bunch of little files, rather than reading one big file, so the random read/write and IOPS performance metrics would be of more interest to you, too. Most companies don't publish that data, probably because those numbers - while still impressive - are smaller than the sequential read/write speeds. IOPS used to be published a bit more readily when SSDs were new, but I suspect most people don't know how to interpret those numbers, so they seem to be much harder to find today. There was one website (that of course I now can't find) comparing some SSD sizes and IOPS performance, and they suggested a doubling of IOPS at higher capacities - which sounds fairly significant.

I'm only speaking up to say that recommending the absolute smallest SSD and doing it on the basis of speed isn't fully the best advice, since larger SSDs are faster. In principle I don't disagree with your strategy, though. If you have enough RAM then in most cases the SSD isn't accessed all that often, so even having a faster drive may not be as meaningful. Compared with traditional HDDs, we're still talking about thousands (or tens of thousands, depending on your model) of IOPS with SSDs compared with IOPS in the low hundreds. With Thunderbolt 3 it also seems less important to "get it right" with the internal SSD the first time; the technology keeps advancing, and in a few years you'll likely be able to buy a SSD at a larger capacity and better price, that also operates faster than Apple's internal SSDs.
 

mavots

macrumors member
Feb 15, 2019
75
15
Seattle, WA
Another option would be to get hold of a Samsung 970 EVO NVME and a NVME TB3 enclosure and run the boot system off of that.
Or take the big files from your Users folder and move them over to the external while keeping the home folder in place. I agree that the boot system and home folder should be on the same drive.
I have this setup with a 1TB external NVME for my Lightroom catalog and video files and it is almost as fast as the internal 500GB SSD. My iTunes Library and photos are in a separate and slower RAID5 HD TB3 drive.