Mohave running too slow on old iMac. Can I revert?

[brn2rnjk1]

Hi,
I thought my old iMac was okay to run 10.14.6 but it is so slow that it isn't really usable. Is it possible to downgrade to an earlier OS? If so, is there an easy link to how to do it?

Thanks,
Jim

 

[DeltaMac]

Which iMac do you have?
What type of drive do you have in that iMac?

Recent macOS systems do not run nicely on an old (spinning) hard drive (if that's what you have), and the APFS file system will also leave you with less than a speed demon.
Depending on which iMac you have, it may be a nice job to replace the old hard drive, with a more-acceptable solid-state drive (SSD), and make your system perform better than it did before you upgraded to Mojave...

 

[MarkC426]

Just re-clone back your old system, that you definitely created before you upgraded.....

 

[bradl]

Just re-clone back your old system, that you definitely created before you upgraded.....

This, or a USB installation stick for the OS you want to revert back to, plus a Time Machine backup to be used with Migration Assistant at the time of OS install.

BL.

 

[brn2rnjk1]

It is a 2012 late with Fusion drive. I have a backup (Super Duper) but no time machine. Not sure how you mean I can revert back from Mohave to an older OS. I just need this to work for a bit longer before we upgrade next year.

 

[bradl]

It is a 2012 late with Fusion drive. I have a backup (Super Duper) but no time machine. Not sure how you mean I can revert back from Mohave to an older OS. I just need this to work for a bit longer before we upgrade next year.

The key here is that you have a backup. That is good. What you can do is this (and this is all assuming that you can not boot to that backup that is made with SuperDuper):

1. On your current OS, download the full installer for the OS you'd like to revert to.
2. Use the createinstallmedia instructions to create a USB installer of the OS that you are reverting to.
3. Boot your Mac, using that installer.
4. in that installer, open Disk Utility, and completely wipe your drive.
5. Lay down a fresh install of the OS. Answer all applicable questions for the install (read: iCloud, etc.)
6. Boot to that new OS.
7. download SuperDuper, and restore everything from your backup.
8. ....
9. profit!!!

Time Machine makes this a bit easier, because it takes care of the restore of your data from the Time Machine backup while doing the OS installation. Oh, and be sure to keep that USB installer stick around in case you need it. You can always boot to that USB stick in an emergency.

Also, it's a good practice to create a new USB installer stick whenever you're going to upgrade to a new major version of MacOS, as well as take a backup of your current OS prior to upgrading. This way you can always revert back quickly in case anything goes wrong.

BL.

 

[saudor]

It is a 2012 late with Fusion drive. I have a backup (Super Duper) but no time machine. Not sure how you mean I can revert back from Mohave to an older OS. I just need this to work for a bit longer before we upgrade next year.

Assuming you have a dedicated superduper disk, all you have to do is hold down option key just before the apple logo appears. Choose the super duper disk. erase your internal disk as HFS+ (mac OS extended) and clone it back.

Alternatively, how big is the fusion drive? If it's not the 1Tb version, you can break the fusion (this is just a combined SSD + HD) and install mojave on the SSD portion and use the spinning disk portion for the rest of your data. For 1TB version, it's not really worth it to do this

 

[BrianBaughn]

What version of macOS are you thinking of running? You'd better check the apps you plan to use for compatibility…and that's two things. One, will the app you need run in the old version of macOS? Two, will the old app (such as a browser) that runs on the old macOS be able to work with the current state of affairs (such as modern websites)?

This is why my 2008 MacBook runs Catalina (unsupported dosdude1 version). If I was running El Capitan (last supported macOS) I wouldn't be able to access certain web content such as Xfinity TV streaming.

If you can't do what saudor suggested about splitting the fusion drive you might just consider running Mojave or Catalina off of an external USB SSD. You could clone your current Mojave installation to an external SSD with Super Duper.

 

[Fishrrman]

OP wrote:
"It is a 2012 late with Fusion drive. I have a backup (Super Duper) but no time machine. Not sure how you mean I can revert back from Mohave to an older OS."

Is your SuperDuper backup Mojave OS?
Or... is it your previous (older) OS?

This is IMPORTANT info, please reply.

IF it's your older OS, can you boot from it? Do this:
a. power down, all the way off
b. connect the backup
c. hold down the option key continuously and press the power on button
d. wait until the startup manager appears
e. can you see the icon for the backup?
f. if so, choose it with the pointer and hit return
g. DOES IT BOOT UP?

IF you can get booted this way, your next job is to:
a. open disk utility
b. go to the view menu and choose "show all devices" (IMPORTANT that you do this IF there is a view menu)
c. select the item "on the left" that represents the fusion drive (I've never owned a fusion drive Mac, not sure how that will be represented)
d. erase it to "Mac OS extended with journaling enabled, GUID partition format"
e. quit disk utility

THEN...
Open SuperDuper.
Now, RE-CLONE the contents of the backup drive BACK TO the fusion drive.

Final step:
Open system preferences and click startup disk.
Click the lock and enter your password.
Now select the fusion drive (again) to be the boot drive.

That's how I'd do it...

 

[MBAir2010]

what i do when Mojave OS acts up on my 2010 MacBook air 4GB i3intel chip
is

1. Zap Pram (restart during chime press command-option PR(lowercase) at once before the apple logo
2. keep 20% SSD free
3. and shut off, on everyday.

i hope this helped!

 

[brn2rnjk1]

OP wrote:
"It is a 2012 late with Fusion drive. I have a backup (Super Duper) but no time machine. Not sure how you mean I can revert back from Mohave to an older OS."

Is your SuperDuper backup Mojave OS?
Or... is it your previous (older) OS?

This is IMPORTANT info, please reply.

IF it's your older OS, can you boot from it? Do this:
a. power down, all the way off
b. connect the backup
c. hold down the option key continuously and press the power on button
d. wait until the startup manager appears
e. can you see the icon for the backup?
f. if so, choose it with the pointer and hit return
g. DOES IT BOOT UP?

IF you can get booted this way, your next job is to:
a. open disk utility
b. go to the view menu and choose "show all devices" (IMPORTANT that you do this IF there is a view menu)
c. select the item "on the left" that represents the fusion drive (I've never owned a fusion drive Mac, not sure how that will be represented)
d. erase it to "Mac OS extended with journaling enabled, GUID partition format"
e. quit disk utility

THEN...
Open SuperDuper.
Now, RE-CLONE the contents of the backup drive BACK TO the fusion drive.

Final step:
Open system preferences and click startup disk.
Click the lock and enter your password.
Now select the fusion drive (again) to be the boot drive.

That's how I'd do it...

How do I tell? I was able to boot up using Super Duper disc but I think it was cloned after the OS (and computer still slow). Thanks

 

[Fishrrman]

Go to "about this Mac" in the Apple menu to see what OS is running.