Resolved SSD part of Fusion Drive close to death ☠️

[gilby101]

But if I "split" the fusion drive wouldn't the iMac just be able to boot from the HDD and be fine?

With a Fusion Drive, the SSD is not simply a cache in front of the HDD. It is a combined drive with data shuffled back and forward. So it can't "just" boot and be fine. But you can run macOS on it. Boot with a bootable installer, erase the HDD and reinstall macOS on the HDD.

But do yourself a favour. Get a USB SSD and boot from it. Just as @Fishrrman says.

 

[HDFan]

There's another thread here at macrumors of which the subject is (roughly), can excessive usage wear out an SSD prematurely?

Looks like your experience here provides an answer...

Maybe, but not a clear case as it is fusion drive. Need a failure report on a pure SSD boot drive which may have higher TBW specs.

 

[ovbacon]

Ok... so now for the dummy question. how do I make a external boot drive. I just got a external ssd drive but I haven't made an external boot drive in ages... My iMac is on OS Monterey 12.6.5

 

[HDFan]

Assuming the drive mounts when you attach it to your mac:

1. Format the SSD as APFS using disk utility

2. Download the appropriate OS

3. Run the installer selecting the external SSD as the install location

 

[Fishrrman]

"how do I make a external boot drive"

Is the new external SSD large enough to hold everything that's on your internal drive?

If the answer is yes, download SuperDuper from here:
download <--click to download
SD is FREE to use for this purpose.
It's also VERY easy to understand and use.

Connect the external drive.
Launch SD.
I believe you can accept the default settings.
Just select your internal drive as the source, and the external SSD as "the target".
Then turn SD loose and it will clone the internal drive to the external.

Now, open the startup disk preference pane.
Do you see the external there as an available boot drive?
Click the lock, then click the icon for the external SSD.
Then, reboot.

Do you get a "good boot"?
If so, congratulations, it's all done.

 

[ovbacon]

@Fishrrman. I'm getting the ssd and enclosure tomorrow... but I was wondering if I use SD am I then just running of the external ssd? If so could I update that to Ventura while my iMac is stuck in Monterey. I always kinda hate having older OS's running due to lesser security.

 

[Fishrrman]

The idea of the external SSD -is- to boot and run from the SSD.

The issue of going from Monterey to Ventura is "separate" from that -- it's a matter of the Mac's age.

I suppose it can be done through that "open core" process, but I know nothing about it.

 

[ovbacon]

The idea of the external SSD -is- to boot and run from the SSD.

The issue of going from Monterey to Ventura is "separate" from that -- it's a matter of the Mac's age.

I suppose it can be done through that "open core" process, but I know nothing about it.

Ahhh, thanks I'll probably just leave Monterey then.... not really in the mood to "bruteforce" a OS upgrade and maybe making things worse.

 

[LeeW]

Oh dear. People think this is some kind of proof of drive wear or failure. Sad.

 

[ovbacon]

Oh dear. People think this is some kind of proof of drive wear or failure. Sad.

Feel free to really explain what you mean instead of throwing out a "not so useful" statement. What is "this" for instance !?

 

[ovbacon]

"how do I make a external boot drive"

Is the new external SSD large enough to hold everything that's on your internal drive?

If the answer is yes, download SuperDuper from here:
download <--click to download
SD is FREE to use for this purpose.
It's also VERY easy to understand and use.

Connect the external drive.
Launch SD.
I believe you can accept the default settings.
Just select your internal drive as the source, and the external SSD as "the target".
Then turn SD loose and it will clone the internal drive to the external.

Now, open the startup disk preference pane.
Do you see the external there as an available boot drive?
Click the lock, then click the icon for the external SSD.
Then, reboot.

Do you get a "good boot"?
If so, congratulations, it's all done.

well... I was able to superduper to the external ssd no problem (although the external ssd is really slows as it has to go through a usb port) and set the boot drive to the ssd and it starts loading but seems to get stuck half way and just sits there

So after a few tries it finally booted from the external... But I'm wondering if I should just have that as an emergency since it took forever to boot...

 

[ovbacon]

I just noticed that the usb-c to usb 3 adapter wasn't really rated for data (just charging) so I'll have to get a better cable so that it actually has a bit of speed (now the ssd is way slower than a external hdd).

 

[ignatius345]

With a Fusion Drive, the SSD is not simply a cache in front of the HDD. It is a combined drive with data shuffled back and forward.

Which is also why the SSDs fail: they get hammered with read/write cycles as all that shuffling happens. Apple's stingy SSD sizes compound the problem. If I'm not mistaken, they used drives as small as 32 GB.

More on the problem here: https://eclecticlight.co/2018/09/04/why-a-fusion-drive-wont-last-as-long-as-an-ssd/

Basically, the Fusion Drive was a clever little hack when SSDs were nosebleed expensive, but their day has passed and any of them out there still in use will probably be dying off soon.

My iMac 5K had a 128 GB SSD as part of its Fusion Drive, and it died exactly the same way as the OPs here. I ended up leaving the blade SSD in place and replacing the SATA HDD with an SSD -- leaving that little mostly-dead blade SSD as a weird extra drive I just never used again.

 

[ovbacon]

Which is also why the SSDs fail: they get hammered with read/write cycles as all that shuffling happens. Apple's stingy SSD sizes compound the problem. If I'm not mistaken, they used drives as small as 32 GB.

More on the problem here: https://eclecticlight.co/2018/09/04/why-a-fusion-drive-wont-last-as-long-as-an-ssd/

Basically, the Fusion Drive was a clever little hack when SSDs were nosebleed expensive, but their day has passed and any of them out there still in use will probably be dying off soon.

My iMac 5K had a 128 GB SSD as part of its Fusion Drive, and it died exactly the same way as the OPs here. I ended up leaving the blade SSD in place and replacing the SATA HDD with an SSD -- leaving that little mostly-dead blade SSD as a weird extra drive I just never used again.

Mine has a 128 GB SSD but I'm hesitant to open the iMac up to replace the hdd for an sdd because the screen is cracked and I do not want to replace the whole monitor part.

 

[ignatius345]

Mine has a 128 GB SSD but I'm hesitant to open the iMac up to replace the hdd for an sdd because the screen is cracked and I do not want to replace the whole monitor part.

Oooh yeah. The glass is heavy and taped up with adhesive. Sounds like a bad idea to remove it!

 

[ovbacon]

Oooh yeah. The glass is heavy and taped up with adhesive. Sounds like a bad idea to remove it!

Yup... It really is only going to be used for some tv watching on occasion. No heavy usage as it's replacement is all up and running. (we don't own a tv or watch much but once in a while we like to watch some netflix or something)

 

[ovbacon]

"how do I make a external boot drive"

Is the new external SSD large enough to hold everything that's on your internal drive?

If the answer is yes, download SuperDuper from here:
download <--click to download
SD is FREE to use for this purpose.
It's also VERY easy to understand and use.

Connect the external drive.
Launch SD.
I believe you can accept the default settings.
Just select your internal drive as the source, and the external SSD as "the target".
Then turn SD loose and it will clone the internal drive to the external.

Now, open the startup disk preference pane.
Do you see the external there as an available boot drive?
Click the lock, then click the icon for the external SSD.
Then, reboot.

Do you get a "good boot"?
If so, congratulations, it's all done.

Cloned the HD with SuperDuper to an external ssd that is faster than the internal hdd but it will not boot from it. it keeps trying and trying and trying until I quit is and boot it to the startup manager and can choose to boot from the internal hdd.

 

[mlody]

If I were you, I would go with the least complicated route and simply un-fusion the drivers and continue to use your iMac with spinning HDD. You already have a better and faster machine, so it is not like you need performance. Plus your iMac is already not supported by the latest macOS, so why the investment?

 

[ovbacon]

So I found out that you can not just clone your HD with superduper or carbon copy cloner since macOS 11.

 

[ovbacon]

If I were you, I would go with the least complicated route and simply un-fusion the drivers and continue to use your iMac with spinning HDD. You already have a better and faster machine, so it is not like you need performance. Plus your iMac is already not supported by the latest macOS, so why the investment?

So how do I un-fusion it and how do I make sure that it starts-up without that ssd and simply boot from the internal hdd. I've noticed that there is a lot of information/help provided without the actual knowledge that was is suggested works. So now when following someone's suggestion I'd like to know if they know for a fact that this will work with the gear at hand. So, this is about a iMac late 2015 running the latest Monterey OS 12.6.5

 

[HDFan]

So I found out that you can not just clone your HD with superduper or carbon copy cloner since macOS 11.

CCC can be forced to do it but (1) it is not recommended and (2) there is no reason to do it. The OS portion can easily be reinstalled by several methods.

 

[mlody]

So how do I un-fusion it and how do I make sure that it starts-up without that ssd and simply boot from the internal hdd. I've noticed that there is a lot of information/help provided without the actual knowledge that was is suggested works. So now when following someone's suggestion I'd like to know if they know for a fact that this will work with the gear at hand. So, this is about a iMac late 2015 running the latest Monterey OS 12.6.5

See if this helps

How to split up a Fusion Drive

Whether you made your own Fusion Drive and want to go back, or want to split up one you got from Apple, we'll show you that it isn't a difficult or lengthy process.

www.macworld.com

Determine which disk started up your Mac

Learn how to check which disk started up your Mac.

support.apple.com

 

[ovbacon]

See if this helps

How to split up a Fusion Drive

Whether you made your own Fusion Drive and want to go back, or want to split up one you got from Apple, we'll show you that it isn't a difficult or lengthy process.

www.macworld.com

Determine which disk started up your Mac

Learn how to check which disk started up your Mac.

support.apple.com

But you have never done it?

 

[ovbacon]

CCC can be forced to do it but (1) it is not recommended and (2) there is no reason to do it. The OS portion can easily be reinstalled by several methods.

I understand it as I have looked at both CCC and SD pretty extensively but how does the idea of being able to instal an OS help me with the failing ssd on my fusion drive. From everything I have found if it does the HD is dead. So from the getgo my question has been... how do I preemptively bypass the ssd part of the fusiondrive so that I can keep using this old iMac. And mainly I'm looking for proven suggestions since there have been a ton of suggestions that are all based on what people think will or might work instead of "this actually works and here you can see find exactly how".

 

[mlody]

But you have never done it?

No, I have done it on few occasion. As I matter of fact, I picked up 21.5' 2017 iMac that I will be cracking open hopefully soon to do some upgrade work too. I am just waiting till WWDC to see if that iMac gets dropped or not and then I will plan accordingly.