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weaztek

macrumors 6502
Original poster
Aug 28, 2009
341
162
Madison
I skimped on my 2018 Mini's SSD and just got a 256GB drive because of pricing. I'm thinking of getting a 1TB SSD on an external USB 3.1 gen.2 enclosure.

How much faster would that be than my existing 3TB HDD over USB-C 3.1 (claimed speed: up to 6Gbps (750MBps) of available bandwidth over SATA III)?

How much slower would the ext. SSD be versus my Mac Mini's internal SSD?
 
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Stephen.R

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Nov 2, 2018
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For Q1:
It depends a bit on the SSD, but the short answer is: quite a bit faster.

A SATA SSD won't really see much difference between USB 3.1 Gen1 or Gen2. It won't hurt if you find a Gen2 controller in the case, but its not gonna make a big difference if you get one that's Gen1.

My mini has the 500GB SSD so it's got a bit of a boost of yours and I can't remember the speeds from the 256GB option, but comparing the ones I have here:

i7/64GB/500GB,
a 250GB Crucial SATA SSD in a 3.1Gen2 case
a 500GB ADATA M2 SSD in a 3.1 Gen2 case (hey lucky you, this POS decided to work for once today, so I could benchmark it)

- the internal SSD gets around 2000MB/sec writes and 2700MB/sec reads.
- the M2 SSD gets about 700MB/sec writes and 900MB/sec reads.
- the SATA SSD gets around 440MB/sec writes and 520MB/sec reads

The only spinning rust I have around that's really testable is a 4-drive RAID10 over eSATA via a TB1 'hub' via a TB3-to-TB2 adapter, and that gets.. up to about 100MB/sec write and read. Its possible the software RAID artificially slows it, but I don't ever remember a spinning drive being particularly speedy.


So some things to keep in mind: I deliberately bought a less-expensive, and therefor slower M2, because the bottleneck here is USB, no point paying for a super fast SSD to be limited to the same speeds. If you can find a TB3 case (or get a ready-to-use model with TB3) then obviously that doesn't apply.


For Q2: I don't have one here to benchmark, but most commercial portable TB3 SSDs advertise speeds comparable with the Mini's internal speeds. If you spend more for a non-portable multi-M2 case, it's likely gonna be faster than your internal drive if setup in a RAID array.


Hope that helps.
 
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Fishrrman

macrumors Core
Feb 20, 2009
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Probably the only SSD that is going to be "as fast as" the internal SSD on the Mini is a Samsung X5 thunderbolt3 drive.

BUT... they are expensive.
Unless you really want to spend the money, I'd pass.

You'll do best by running the internal SSD as your boot drive, but keeping "large libraries" of stuff (such as movies, music and photos) on an EXTERNAL USB3 drive.

You don't want this to be "a boot drive" (even though it might have a copy of the OS on it) -- rather, it should become your "primary external storage" drive.
(Aside: of course it COULD be "a boot drive" -- but it's just not going to be as fast as the internal SSD)

It could be either:
- USB3 SSD
or
- USB3.1 gen2 SSD

A USB3 gen1 drive will give you read speeds around 430mbps.
A USB3.1 gen2 drive will give you read speeds around 950mbps.

Twice as fast, yes.
But... something to be aware of... the gen2 drives seem to run considerably hotter than do the "regular" USB3 drives (which seldom even get above being "warm").

What I'd suggest:
Get a "bare" 2.5" SATA SSD. 1tb should run around $100 if you shop carefully.
Get this USB3 enclosure:
(I have the USB3.0 version, it's built like a tank)

This will give you a solid USB3 external drive for storing data and also serving as an external boot drive when needed.

One other thing:
Remember that you will have TWO "primary" drives:
- your "primary internal" boot SSD
and
- your "primary external" storage SSD

So... you now have to BACK UP BOTH drives.
As always, I recommend only CarbonCopyCloner or SuperDuper for this job.
You could PARTITION the existing HDD you have:
1st partition - 256gb (this becomes a cloned backup of your internal SSD)
2nd partition - whatever is left (this becomes a backup of your external SSD).
or perhaps even a 3rd partition for just "scratch storage).
 
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Stephen.R

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Probably the only SSD that is going to be "as fast as" the internal SSD on the Mini is a Samsung X5 thunderbolt3 drive.
There are multiple brands of TB3 SSDs with similar speeds. Why people continue to think Samsung is the only manufacturer in this space is beyond me.
 
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weaztek

macrumors 6502
Original poster
Aug 28, 2009
341
162
Madison
Thanks for the replies! I should have mentioned, that my int. SSD is the boot drive and that takes nearly 1/2 the space of the (256GB) drive. Email, fonts, and apps all add up! Then my ext. 3TB HDD runs on the Pluggable USB 3.1 dock. Basically this frees up 146GB for my working files) which happen to be photos. Once I've completed a project, I dump everything onto the ext. HDD for long-term storage.

So if and when I get a second SSD, it would be for my working photo files. I did a shoot last month with 120GB of photos and that didn't fit on my int. drive. It's the first time that happened, but probably won't be the last. I ended up simply downloading those files to my ext. HDD and working on them off that.

I did not know Thunderbolts are a faster connection. I think what i'll do is wait for a 1-2TB Thunderbolt drive to drop in price and grab one then.
 

lixuelai

macrumors 6502a
Oct 29, 2008
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A 1TB USB 3.1 SSD (Sandisk Extreme, Samsung T5 etc) can be had for <$150. Amazon was selling the Sandisk for $135 (though higher now). You may be able to find a deal during Black Friday.

Thunderbolt will be faster but compared to HDD, you might as well get a USB 3.1 now rather than waiting for prices to drop.
 

Fishrrman

macrumors Core
Feb 20, 2009
22,745
8,581
"I think what i'll do is wait for a 1-2TB Thunderbolt drive to drop in price and grab one then."

I would advise against this.
You may be waiting a long time!
 
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Fishrrman

macrumors Core
Feb 20, 2009
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"I'm thinking of picking up the Sabrent Rocket Pro 512TB SSD NVMe for $90.
https://www.techbargains.com/deals/sabrent-rocket-pro-ssd"


That looks to be a USB3.1 gen2 speed drive/enclosure combination.
It -should- yield reads in the 960-965mbps range.

As such, it is probably NOT "faster than" the 2018 Mini's internal SSD drive.

But it's still good for external storage, or as a secondary boot drive.
 

weaztek

macrumors 6502
Original poster
Aug 28, 2009
341
162
Madison
Here's how this all played out...

I purchased a Sabrent Rocket Pro 512TB SSD NVMe and it did not test well for me at all. It could be the version of Catalina I was running, because my system was pretty messed up overall. I sent that drive back and instead picked up a VisionTek 512GB Thunderbolt 3 External NVMe SSD for $95. Wow. Really happy with it so far.
 

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Super Spartan

macrumors 6502a
Mar 10, 2018
607
264
Dubai
I skimped on my 2018 Mini's SSD and just got a 256GB drive because of pricing. I'm thinking of getting a 1TB SSD on an external USB 3.1 gen.2 enclosure.

How much faster would that be than my existing 3TB HDD over USB-C 3.1 (claimed speed: up to 6Gbps (750MBps) of available bandwidth over SATA III)?

How much slower would the ext. SSD be versus my Mac Mini's internal SSD?
I have a 2TB Samsung T5 Portable SSD. Best purchase I ever made considering how many times I format, makes copying back my data much faster. We are talking 450-500 MB/S vs the HDD/s 100 MB/s or so speed.
 
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