I would buy an external SSD of the size you will get in your next iMac, use that to boot from ad interim and buy a new iMac when the new model comes out.
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I, too, am using a Samsung SSD ( 860 EVO 1TB 2.5 Inch SATA III Internal SSD), in an inexpensive Sabrent 2.5-Inch SATA to USB 3.0 external USB 3 enclosure. I didn’t want to risk converting the 1TB Fusion drive in my 2014 27" iMac to APFS. So I tested and then upgraded to Mojave on the SSD. The external drive doesn’t work as fast as it would installed internally, but I don’t have the nerve to open up the iMac to install it there myself, nor the scratch to pay someone else to do it. The SSD boots “fast enough”, at least as fast as the original Fusion drive. Applications launch more quickly and run reliably. I haven’t had any of the problems reported by some people, so I guess I should count myself lucky. It’s worth noting that the external SSD drive won’t boot connected to a powered USB hub, but must be plugged into one of the iMac’s own USB ports.
I have an OWC Mercury On-the-Go Pro USB 3 enclosure I got on sale for use with another SSD, when I can afford one. I’ll use this for Catalina, which I’m not yet ready for. I still have too many 32 bit apps. I won’t be buying an OWC SSD, however, as they are too expensive (Though the Samsung was on sale at the time I got it. It’s more expensive now).
I’ve used a number of these OWC housings before. The biggest problem with them is that the chipset in the housing sometimes fails, but that happens to other external hard drives as well. In the past I liked them, though, because OWC offered the On-the-Go models with multiple connections on the same housing, including USB and FireWire, giving them flexibility in supporting various older Macs. They no longer have as many housings available, only two, in fact. But they are sturdy with a good heat sink, though that’s not so important with an SSD.
For the future buy a copy of LIFESPAN from micromat which checks SSD’s.
A “GOOD” shop should test the SSD before installing and backup all your data. But maybe not.
In my case, it might not have helped as the SSD was working well enough to install a system and boot, but would intermittently fail when run for more than a an hour or so. I suppose it would depend on (1) what was actually wrong with the SSD and (2) what kind of test was run.
Presumably you formatted the SSD and installed macOS on it using a different Mac before putting in the iMac?
I have another 2014 iMac with a bad drive to experiment on now, so I’m thinking about going down this route.
Actually, no. Joshua installed the drive in the iMac and then asked me to do the adhesive steps to re-attach the screen. At that point, the iMac was on its back with the screen removed but connected, supported above the frame by a pair of small cardboard boxes. I didn’t want to risk putting the adhesive on and then discovering that Josh or I had made some sort of mistake, so I powered on the machine, formatted the drive, and installed macOS. (I don’t remember if we used external media or net install, but likely the latter.) Once I was convinced (incorrectly, alas) that the drive and installation were good, I proceeded to clean all the surfaces, apply the double-stick tape. and re-attach the screen.
Ah, good to know that it can be done that way—thanks!
I’m debating between the OWC SSDs and a Samsung 860, which is a good bit cheaper.
If you’re thinking of installing the Samsung internally, be aware that the OWC kit came with a tool to remove the adhesive (easily worked around), some suction cups for lifting the screen (I think someone already posted a link to an alternative), some Torx drivers you probably already have, the adhesive strips for re-attaching the screen (which I’m guessing would be hard to find elsewhere), and a thermal sensor that attached to the new drive with adhesive. This last was to emulate a function which the Apple-specific HDD we were replacing offered that the SSD didn’t, but without which the iMac wouldn’t operate properly. I didn’t anticipate the need when I was debating between the OWC kit and a bare drive. Since you’re starting from an SSD, this might not be necessary for your iMac but you might want to be sure. It would, I think, be difficult to come up with the appropriate thermistor (I assume), cable, and connectors to fake it.
Of course, the excellent OWC installation video is available to all.
Is netbooting an option for Mac users? It was a thing for large groups of Macs, but I haven’t heard it mentioned for decades.
I believe netboot still works, though I haven’t used it. What I was referring to should properly be called “macOS Internet Recovery.” Sorry.
NetBoot is deprecated and doesn’t work on T2-equipped Macs.
Since we are in adamant agreement I think you are very smart and so does Jack my wonder dog.
I never bothered to clone parts of disks with either program but regularly run rsync a command line program. It is very powerful and solid. I generally use it in combination with finder I type rsync at the prompt and then drag and drop the source and destination paths from finder windows after the command so it looks like this.
rsync source destination
Have you verified rsync is copying everything? Forks, ACLs, extended attributes, etc. I tried rsync a while ago (I’ve used it on Unix derivatives for years), and even using the options that are supposed to copy everything, I couldn’t get it to. I can’t remember what version of macOS that was on though so maybe it works on recent versions.
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CCC uses rsync behind the scenes I am pretty sure…but doing it from terminal means scripting and cron and all that other jazz to get automated copies…CCC provides a nice GUI that eliminates the confusion factor. I could do the script/cron stuff…but that’s a lot harder to make sure you don’t screw it up.
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Not to derail too much here, but as a Mac user is there more than -aE we should apply to rsync to make sure we really grab all the permissions, time stamps, and metadata?
That…and the lack of automation sans writing scripts…is why CCc is a better idea for most users. Rsync has many flags one can set and is easy to screw up unless you do it a lot IMO.
If I remember correctly, CCC was originally based on rsync, but today uses its own code, precisely because stock rsync implementations don’t support every feature of Apple’s file systems.
It does, however, continue to use the rsync protocol in an SSH tunnel for remote backups (See also Using Carbon Copy Cloner to back up to/from another Macintosh on your network)
I think it was doing forks years ago, back when Nisus Writer was using them, as I remember being told one fork had a text document the other fork the format information. Idea was if you lost the format you still had the content as unformed text. Anyway I never had a problem. Don’t know if this is still true but I still haven’t had a problem. As for ACLs etc. I rely on maintain control over the box. If no one can get to it and I keep it off the net as much as possible I figure I won’t need them. In any case if they aren’t copied, and I don’t know why they wouldn’t be, I expect the OS to add them at the destination. But then again maybe I am naive about how that stuff all works. I retired about 25 years ago and was concerned about that stuff at work about 10 years before that. 