How to set up an external SSD

ravinder08

macrumors 6502
Original poster
Jun 11, 2010
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44
thinking of getting an external ssd for my late 2012 iMac. What's the best way of hooking up an ssd then using it as just the boot disk for the OS and having the docs etc stored on the internal HD?
Many thanks
 

colinsky

macrumors member
Apr 3, 2009
51
6
I use a USB 3 enclosure for a 1TB SSD external boot drive on my 2015 5K iMac. For most SSDs, the only advantage of the Thunderbolt enclosure is TRIM compliance.
 
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ravinder08

macrumors 6502
Original poster
Jun 11, 2010
296
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Silicon Power make a 240GB Thunderbolt SSD. Just needs hooking up to the Thunderbolt port, and I used a Twelve South Rack which mounts on the iMac leg to hold it. In System Preferences select as the Boot Drive.
Would I clone the HD and put that on the SSD?
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I use a USB 3 enclosure for a 1TB SSD external boot drive on my 2015 5K iMac. For most SSDs, the only advantage of the Thunderbolt enclosure is TRIM compliance.
Does TRIM compliance matter?
 

Fishrrman

macrumors Core
Feb 20, 2009
19,609
6,828
Don't overthink this.
There's essentially no difference to "setting up" an external USB3 SSD, as there would be to setting up an internal drive.

The Mac almost never cares about which drive is the boot drive.
So long as it finds a bootable drive, it "runs with it".
I'm surprised by how many Mac users don't reailize this.

That said...

There IS a consideration.
That is, will the SSD be 256gb, 512gb, or 1tb?
If you use a smaller-capacity SSD, you will want to keep large libraries of pics, movies, and music on the internal HDD.
There's no reason to "clog up" the SSD with them. They probably aren't accessed often and you want to keep the SSD "lean, clean, and mean".

I would set up the SSD external booter to have:
- the OS (of course)
- your apps
- your accounts (with large libraries left on the hdd)
- keep smaller files that you're working on, on the SSD for speed.

Also -- leave the internal HDD to remain bootable.
You always, ALWAYS, ALWAYS want a "second fully-bootable drive" nearby and quickly available.

And... you might want to consider a SECOND external drive (doesn't have to be an SSD) to serve as a backup to the "external boot" drive.

Personal experience:
I use a 240gb external booter for my late-2012 Mac Mini. I have the SSD partitioned. One partition is my "boot partition". The second serves as my "Main" partition, where all my data files (going back 30+ years!) are stored.
I back both of these up to similar partitions on the Mini's internal 1tb drive.

The Mac Mini has run GREAT for more than four years in this configuration.
TRIM (or the lack of it because of USB3) has NEVER been an issue.
 
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Fravin

macrumors 6502
Mar 8, 2017
250
131
Rio de Janeiro, Brazil
Don't overthink this.
Personal experience:
I use a 240gb external booter for my late-2012 Mac Mini. I have the SSD partitioned. One partition is my "boot partition". The second serves as my "Main" partition, where all my data files (going back 30+ years!) are stored.
I back both of these up to similar partitions on the Mini's internal 1tb drive.
Quite Interesting this point. An 3.0 USB Case with a SSD will run faster than my fusion drive?

My fusion is the 24Gb+1THDD type.
 

nambuccaheadsau

macrumors 68000
Oct 19, 2007
1,835
432
Nambucca Heads Australia
I a word from my experience no.

I used an external Thunderbolt SSD as an external boot drive some time ago on a 2011 iMac, and it was a great boost, however nowhere near as fast as the Fusion drive.
 
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