Resolved 2017 iMac 27" external SSD as boot drive?

[Plan-B]

Thanks to all the contributors to this thread. I'm about to take the plunge! I had a 2011 i7 iMac and bought a Sandisk 1TB SSD on Prime Day this summer with the intention of installing it into my older machine. I even bought the OWC install kit and NewerTech Adaptadrive. But before I got a chance to do the swap, my old iMac died on me. So with Best Buy having a deal on the base model 27" 5K iMac, I went for a replacement over a repair. But the seat-of-the pants speed evaluation has this newer machine feeling exactly as fast as my old one. So I have a Satechi external USB-C (3.1 Gen 2) enclosure arriving tomorrow. The Sandisk SSD has been sitting on my desk for 4 months and will have a home soon. I plan on using CCC to clone over the internal drive, and then continuing to use CCC to mirror the SSD back to the internal. That way, if the Sandisk SSD fails, I can boot from the internal drive without missing a step.

I'm very curious to hear from those who have gone the external SSD route, updated to Mojave, and have figured out to fix any performance/slow booting issues.

 

[MALmen]

Is it the same issue with mojave slow boot using a Samsung X5 TB3 drive?

 

[AC Rempt]

This was a very helpful thread that lead me to buying a Samsung T5 1TB for my 27 inch 2017 iMac. I made a clone of my fusion drive via Carbon Copy Cloner, and then booted from the T5. So far, it's pretty spry with apps launching quickly. I have no official benchmarks, but I can definitely see a ig difference.

My plan is to wait a week or so to see if any issues emerge, and then erase the fusion drive to use as additional storage. I have another external drive for backup.

 

[Plan-B]

My plan is to wait a week or so to see if any issues emerge, and then erase the fusion drive to use as additional storage. I have another external drive for backup.

How badly do you need that internal terabyte for extra storage? I ask because when I did this last Friday, I ended up using CCC to reverse the cloning direction. Now, the external SSD backs up to the internal Fusion every couple of hours as a scheduled CCC task. There is a possibility that my external SSD will croak before the internal drive does. If that happens, I can yank the USB cable and boot from the internal drive as if nothing happened, albeit at a much slower speed. I couldn't pass up the convenience of the internal Fusion being the backup, but then I have a Synology NAS and several other USB3 HDDs connected. External drives are crazy cheap these days.

 

[Fishrrman]

Plan B wrote:
"There is a possibility that my external SSD will croak before the internal drive does. If that happens, I can yank the USB cable and boot from the internal drive as if nothing happened, albeit at a much slower speed"

This is a good strategy, and I've done pretty much the same for the past 6 years.

I boot and run my Mac Mini (which has a 1tb internal HDD) from an external USB3 SSD.
But I have the internal drive partitioned into several smaller volumes, and the first one contains a CCC cloned backup of my external boot SSD.

If anything goes wrong with the SSD -- or if I just need "a second boot source" for some reason -- the internal drive is always "there and bootable" at a moment's notice.

 

[virtualandy]

First - thanks for this thread + comments, helpful for my situation of a 2012 iMac that just saw its spinny disk portion of a 3TB fusion drive fail.
I bought a USB3 enclosure and 1TB SSD ($150 for both, couldn't resist) and have been debating on booting off of that or re-using the internal SSD (128GB).

Did anyone keep using the internal SSD as the boot? Any issues? Maybe just use it as a recovery option?

 

[AC Rempt]

How badly do you need that internal terabyte for extra storage? I ask because when I did this last Friday, I ended up using CCC to reverse the cloning direction. Now, the external SSD backs up to the internal Fusion every couple of hours as a scheduled CCC task. There is a possibility that my external SSD will croak before the internal drive does. If that happens, I can yank the USB cable and boot from the internal drive as if nothing happened, albeit at a much slower speed. I couldn't pass up the convenience of the internal Fusion being the backup, but then I have a Synology NAS and several other USB3 HDDs connected. External drives are crazy cheap these days.

Good point. I was after the minor performance bump more than the storage, so I think I'l take your advice. It'll give me two cloned backups which pleases my paranoia about hardware failures.

 

[Counting Steps]

This is a very interesting thread as I've been thinking about doing this on my 2015 iMac for a while now.

I'm probably going to get the Samsung T5 500GB, then eventually use the internal drive for my CCC clone as Plan-B has suggested.

I'm currently running High Sierra, but am a little concerned about the comments regarding problems when updating to Mojave due to APFS. Is there any answer to this now, or can changing to APFS be bypassed when updating?

 

[Plan-B]

I'm currently running High Sierra, but am a little concerned about the comments regarding problems when updating to Mojave due to APFS. Is there any answer to this now, or can changing to APFS be bypassed when updating?

The only thing I've seen is if you clone a Mojave boot disk to an HFS+ formatted one, it should retain HFS+. For me, there doesn't seem to be anything in Mojave that motivates me to the "I must have that" level, so I'm sticking with High Sierra.

 

[Fishrrman]

Counting Steps wrote in #83 above:
"I'm currently running High Sierra, but am a little concerned about the comments regarding problems when updating to Mojave due to APFS. Is there any answer to this now, or can changing to APFS be bypassed when updating?"

You didn't tell us:
- what KIND of drive is inside the 2015 iMac (fusion or other?)?
- what format it's currently in? (HFS+?)

If you're going to boot and run from an EXTERNAL SSD, I suggest you just "clone over" your current OS install using either CarbonCopyCloner or SuperDuper (either are free to download and use for 30 days -- this method costs you $0).
Simple and easy (probably the fastest way to do it, as well).

If you are currently using High Sierra and your internal drive is HFS+...
And IF you are happy with the OS install (i.e., no software problems) as it is...
THEN my recommendation is to stay with High Sierra for now, until Mojave becomes a "more mature" OS.

I always "stay back" an OS release or two.
The older versions just run better for me.

 

[Counting Steps]

Ok, thanks. Yeah, I'm in no rush to update to Mojave, in fact I only updated to High Sierra a couple of months ago , but if eventually it becomes desirable to update, how do you get around this, or do you consider the slow booting problems with APFS just to be down to it being early days / teething problems for the format?
[doublepost=1547567876][/doublepost]Thanks Fishrrman, my current HDD is HFS+ 1TB (not fusion) and I would intend to clone it from my CCC backup.
I'm happy with High Sierra and in fact only updated a couple of months ago, like you, I never rush into it, always let the bugs get ironed out first.

 

[mcfraga]

I have been testing my iMac late 2012 with internal fusion drive and external SSD bu USB 3 enclosure. Things have gone quite peachy after long booting time, faster speeds overall for a some years old machine, and as I don't normally reboot it, i appreciate the gained speed than the lost on a responsive boot.

I guess many of you have gone similar route (USB, THUNDERBOLT whatever connection) but i am interested to know if anyone has "designed" a backup plan so the SSD BOOT DRIVE can be CLONED as BOOTABLE to the internal drive, so everything is the same, and updated, and if by any chance, the SSD goes wrong, I could just boot up from the internal drive and keep everything as good as new.

My original plan was taking "small" SSD time machine backups to my Time capsule, and big internal HDD backup to a external USB drive. But i think I would gain another level of security/confidence if SSD and HDD where like clones (at least the boot part) Guessing if Carbon Copy Cloner, Super duper, or any other free alternative could do this in an easy to manage way???

Hope it is understandable, my english is not my main language, and even if I like apple computers from long time, not really into deep stuff.

 

[Counting Steps]

I guess many of you have gone similar route (USB, THUNDERBOLT whatever connection) but i am interested to know if anyone has "designed" a backup plan so the SSD BOOT DRIVE can be CLONED as BOOTABLE to the internal drive, so everything is the same, and updated, and if by any chance, the SSD goes wrong, I could just boot up from the internal drive and keep everything as good as new.

This is what I want to do later.
I now have my iMac running very well from a Samsung T5 500GB SSD and still continue cloning with Carbon Copy Cloner to my original external drive, but want eventually to automate that cloning to the internal drive which Plan_B mentions above #79.

 

[Fishrrman]

mcfraga wrote:
"i am interested to know if anyone has "designed" a backup plan so the SSD BOOT DRIVE can be CLONED as BOOTABLE to the internal drive, so everything is the same"

I've been doing this for SIX YEARS with my 2012 Mac Mini.

On the day I took it out of the box, I set up a 240gb USB3 SSD to be the boot drive.

I then partitioned the internal 1gb HDD, with the "first" partition being large enough to hold a clone of my external boot drive.

Thus, I have an exact, IMMEDIATELY-BOOTABLE "second copy" of my boot SSD -- right on the (slower, but still usable) internal HDD.

 

[mcfraga]

Firshman Wrote:
"On the day I took it out of the box, I set up a 240gb USB3 SSD to be the boot drive.

I then partitioned the internal 1gb HDD, with the "first" partition being large enough to hold a clone of my external boot drive."

Could this be done with a CCC / backup solution that keeps the internal Fusion drive BOOTABLE but needs no repartitioning? Is it needed so SSD can be cloned and bootable in the internal, or could there be another option, somewhat that could clone the bootable part keeping the rest of data intact ?

 

[casperes1996]

Could this be done with a CCC / backup solution that keeps the internal Fusion drive BOOTABLE but needs no repartitioning? Is it needed so SSD can be cloned and bootable in the internal, or could there be another option, somewhat that could clone the bootable part keeping the rest of data intact ?

I'm really not sure exactly what you mean. "Kepping the rest of the data intact"? What's that supposed to mean?

The idea behind repartitioning is so that the entire Fusion Drive doesn't need to go to the backup. If the Fusion Drive and the external drive are the same size, repartitioning becomes redundant, but if your boot drive is let's say 512GB, making a 512GB partition on the Fusion means you can keep the boot drive and that partition of the Fusion in sync and bootable, whilst still having access to the remaining space of the Fusion as data storage.

 

[mcfraga]

I meant if this can ve achieved without having to repartition the internal FUSION DRIVE. So the External SSD gets cloned or copied to internal Fusion without touching the rest of data.

 

[Plan-B]

I meant if this can ve achieved without having to repartition the internal FUSION DRIVE. So the External SSD gets cloned or copied to internal Fusion without touching the rest of data.

I think you need to be more specific about what you mean when you say: "the rest of data"

If you're cloning a drive, the whole point of it is that there isn't any additional data. What's on one drive is mirrored on another drive, bit for bit. That's cloning. Carbon Copy Cloner has a feature which is an exception. They call it SafetyNet in that files from your source drive which are deleted are retained on the cloned, destination drive. Just in case you change your mind and decide you wan't to get it back. In that case, there is additional data taking up space on your destination drive. I haven't used Super Duper so there may be an exception there too.

If you define what you mean by the rest of the data, you might get better answers.

 

[casperes1996]

I meant if this can ve achieved without having to repartition the internal FUSION DRIVE. So the External SSD gets cloned or copied to internal Fusion without touching the rest of data.

I agree with Plan-B that this is still ambiguous, but if I do understand you correctly, the answer is no.

 

[nihil0]

Is it the same issue with mojave slow boot using a Samsung X5 TB3 drive?

I second this question. I would like to buy X5 for my 2017 27-inch iMac as well but I am afraid that it will not work as intended and will freeze or lag on boot

 

[Djenk]

Hey folks!

Great thread!

First post here... I’m a fan off SSDs and have been using them in my (now ancient) iMacs. I am ready to pony up for a new 2019 iMac, but am not wanting to shell out what they ask for SSDs inside. I’m not afraid to install SSDs inside the machine, but figure I can wait until my warranty expires, so....

Just had to recycle my 2003 (!) iMac, and pulled out the Crucial MX100 512GB internal SSD that I installed - (forgot how easy it was to do back then!!) which made it run like a prince - and I’m wondering about this:

I have a 2008 iMac now running El Capitain, which I will keep for music studio work (it has a 1TB internal SSD). There is very little on the old Crucial right now - Snow Leopard, some photos etc. I’m considering pulling off whatever is useful onto my 2008 iMac, and then setting it up as a boot disc for a new iMac.

I could then buy a baseline 21.5” 2019 3.6Ghz iMac (8gb RAM, 1TB HDD) and put the Crucial in an enclosure for now, then after the warranty expires go in for internal installation of SSD (and likely RAM at that point).

I’ve never used an enclosure, as I’ve always installed internally, so I’d love your advice about that (and the proper cable to use), and more generally, if this is just a dumb idea...! Just hate forking over more than necessary - and also have equipment on hand that could be of use, I imagine....?

Many thanks in advance!

 

[madeinjersey]

If I clone my internal HDD to en external SSD and boot up from the SSD is it then possible to use the internal HDD for storage?

 

[adamk77]

 

 

[jerrycoffman47]

If I clone my internal HDD to en external SSD and boot up from the SSD is it then possible to use the internal HDD for storage?

yes you can

 

[Fishrrman]

"If I clone my internal HDD to en external SSD and boot up from the SSD is it then possible to use the internal HDD for storage?"

Yes.
Sure.
Of course.

HOWEVER...

I'd leave a copy of the OS on the internal drive, just to keep it bootable.
You always ALWAYS ALWAYS want to have a SECOND drive close-at-hand that is "bootable to the finder".

On my 2012 Mini (which is getting replaced this afternoon with a 2018 Mini), I booted and ran it using an external SSD from the first day I took it out of the box in 2013. I used the internal HDD "as the backup", so that if the SSD wouldn't boot, I could "switch" to the internal drive and keep right on going. I don't recall having to do that much (at all?), but again, you ALWAYS want to have a second fully-bootable clone of your "main drive" close by.

A Time Machine backup is USELESS in such moments of need.