Factory Reset iMac to fix issues

[lurcher]

So I have tried everything to get my 2017 iMac to get out of its sluggish performance without any improvement, so I'm looking to do a factory reset. The reason being is for the last few iMacs I've got I've done the migration assistant setup, so I've probably got a ton of old stuff on there causing problems. Either that or it's a hardware issue.

I see now you don't have to do a usb backup of the OS when doing a reset?

My main worry is saving my emails, email settings, passwords and prefs. Is there an easy way to do this? I assume for the actual emails I need to export each mailbox and import again?

Anything else I need to do? Obviously I will do a full timemachine just in case.

 

[Fishrrman]

If you want to "wipe it and start over", here's what I'd suggest:

FIRST -- BACK UP YOUR DATA.
If you use time machine, run it before you do the following.
Actually, my preference is for either CarbonCopyCloner or SuperDuper.

NEXT -- BOOT TO INTERNET RECOVERY
This is NOT THE SAME as "the recovery partition".

Power down (all the way off).
Then, hold down
Command-OPTION-R
... and press the power on button.

KEEP HOLDING DOWN those keys for a while!
If you connect via wifi, when it asks for the password, let the keys go and type it in (you don't need to hold down the startup key combo anymore).
(actually, ethernet is better if you have it)

The internet utilities take a while to load, so be patient "as the globe spins".

When you get to the utilities, open disk utility.
VERY IMPORTANT STEP, DO NOT SKIP:
Go to the view menu and choose "show all devices".

Now look at "the list on the left".
The topmost item is the physical drive inside.
(I don't know what it shows for a fusion drive, I've never touched a Mac with a fusion drive inside)
Select the physical drive by clicking on it, then click the erase button.

Erase to "APFS, GUID partition format".
Then quit disk utility and open the OS installer.

Start clicking through.
The Mac will restart one or more times, and the screen will go dark for a minute or more, with no other indication of activity. Be patient.

When the install is done, you'll see the initial setup screen (choose your language).

What you do at this point is UP TO YOU.
You can either connect the tm backup and restore from it, OR...
... you can do a completely fresh install, new account, etc.

WARNING WARNING WARNING
If you choose to do a completely new install, you may face permissions problems when trying to "bring over" data from the tm backup.
It doesn't matter if you used the same username and password -- the new OS install may see the old backup as "alien" and refuse to bring over stuff from it.

This is why I ALWAYS recommend either a CCC or SD cloned backup instead of tm.
If you have a cloned backup, it's EASY (child's play) to over-ride permissions issues and bring stuff over from the backup drive.

Maybe tm can do this to.
But I've never, ever used it.

I suggest you PRINT OUT this reply.
Good luck.

 

[ThrowerGB]

This is a nicely set out set of instructions. Thank you.
It leads me to a question about permissions based on your WARNING.
I got rid of Boinc several years ago (I was running SETI using Boinc). I thought I'd erased it all, but two Boinc Groups are now appearing in Users and Groups. Those Groups have taken ownership of files and folders that weren't associated with Boinc. And the problem appears on TM as well. This may have happened when I originally loaded Ventura. I've loaded each version of Ventura as they came out and am currently running 13.3.1 (a). I'm trying to figure out how to recover.
The two Groups are boinc_manager and boinc_project. They both appear as Group Members of each other. This seems recursive and I wonder if that is the problem.
I have two User accounts, both with Admin status which appear as User Members of each of the boinc Groups.
There are no other Groups displayed in Users & Groups, however on Info screens of many files and folders under Sharing & Permissions, Groups such as staff, system and everyone are listed. Actually I can't tell if they are Users or Groups.
In System Settings > Users & Groups, I have the opportunity to remove my two User Members from those two Groups. And I have the opportunity to just delete the two boinc groups. I'd prefer to delete them, but I don't know what will happen. Will some other User or Group take over? Will I make things worse? Alternatively I could remove my two Users from being members of the two boinc Groups.
Perhaps my problem is in not understanding the difference between Users and Groups?

 

[lurcher]

If you want to "wipe it and start over", here's what I'd suggest:

FIRST -- BACK UP YOUR DATA.
If you use time machine, run it before you do the following.
Actually, my preference is for either CarbonCopyCloner or SuperDuper.

NEXT -- BOOT TO INTERNET RECOVERY
This is NOT THE SAME as "the recovery partition".

Power down (all the way off).
Then, hold down
Command-OPTION-R
... and press the power on button.

KEEP HOLDING DOWN those keys for a while!
If you connect via wifi, when it asks for the password, let the keys go and type it in (you don't need to hold down the startup key combo anymore).
(actually, ethernet is better if you have it)

The internet utilities take a while to load, so be patient "as the globe spins".

When you get to the utilities, open disk utility.
VERY IMPORTANT STEP, DO NOT SKIP:
Go to the view menu and choose "show all devices".

Now look at "the list on the left".
The topmost item is the physical drive inside.
(I don't know what it shows for a fusion drive, I've never touched a Mac with a fusion drive inside)
Select the physical drive by clicking on it, then click the erase button.

Erase to "APFS, GUID partition format".
Then quit disk utility and open the OS installer.

Start clicking through.
The Mac will restart one or more times, and the screen will go dark for a minute or more, with no other indication of activity. Be patient.

When the install is done, you'll see the initial setup screen (choose your language).

What you do at this point is UP TO YOU.
You can either connect the tm backup and restore from it, OR...
... you can do a completely fresh install, new account, etc.

WARNING WARNING WARNING
If you choose to do a completely new install, you may face permissions problems when trying to "bring over" data from the tm backup.
It doesn't matter if you used the same username and password -- the new OS install may see the old backup as "alien" and refuse to bring over stuff from it.

This is why I ALWAYS recommend either a CCC or SD cloned backup instead of tm.
If you have a cloned backup, it's EASY (child's play) to over-ride permissions issues and bring stuff over from the backup drive.

Maybe tm can do this to.
But I've never, ever used it.

I suggest you PRINT OUT this reply.
Good luck.

Thanks for those instructions. I would want to do a fresh install to make sure anything from the past is not going to give me problems again. However, how do I get my emails and setting back - is that possible? I have several emails on different domains, together with my apple one.

 

[colodane]

Power down (all the way off).
Then, hold down
Command-OPTION-R
... and press the power on button.

Thanks for the detailed instructions - may come in handy someday!

Question: Would I need a wired keyboard to do this, or would a wireless keyboard work? Or, perhaps, my Apple bluetooth keyboard connected via lightning cable?

 

[DeltaMac]

What kind of boot drive do you in that iMac, anyway?
Maye your iMac is still sluggish because of the spinning hard drive that you have?

The default drive is often a 1TB spinning hard drive, which will be sluggish.
Or you may have a "fusion" drive, which uses both a spinning hard drive, plus a very small SSD, combined by software into a single virtual drive. works pretty good, but an aging spinner can affect everything you do.
If you have either of those drive options, even a "factory reset" will not change anything, as you will still have the same hardware, and may make things worse. If your hard drive is approaching failure, a full reset (wiping and reinstalling everything) might actually accelerate that failure.

 

[lurcher]

Jeez, now you're scaring me! It is the fusion drive I have, and I can 9 times out of 10 hear it chugging away in the background. I was hoping to wait until the new iMacs come out.

 

[Feek]

FIRST -- BACK UP YOUR DATA.

SECOND
Back it up again! Use a different method to a different device.

THIRD
Make sure you can read the backups.

Then and only then, proceed.

 

[lurcher]

I have just run DriveDX and it says zero issues found, the drive is healthy and SSD lifetime left indicator is a healthy 84% which seems good after 6 years.

 

[DeltaMac]

Jeez, now you're scaring me! It is the fusion drive I have, and I can 9 times out of 10 hear it chugging away in the background. I was hoping to wait until the new iMacs come out.

The fusion drive is two separate devices - a spinning hard drive, and a blade-type SSD. The SSD, of course, is silent.

 

[jagolden]

Thanks for the detailed instructions - may come in handy someday!

Question: Would I need a wired keyboard to do this, or would a wireless keyboard work? Or, perhaps, my Apple bluetooth keyboard connected via lightning cable?

Personally, I recommend a wired keyboard and mouse when doing these thing.

 

[DeltaMac]

Yes, connecting your Magic keyboard to your iMac with the USB charging cable will enable it to work as a wired keyboard.