iMacs with 1TB Fusion Drive and 32 (28) GB SSD blade - unbearably slow boot times

Having waited for more than three months for a solution to the unbearably slow boot times of Big Sur on my iMac 27inch 5K 2019 with a 1TB Fusion Drive featuring a 32 (28) GB SSD blade and 40 GB of RAM, I have decided to downgrade my system to Catalina.

Previously, I had tried all possible tricks of the trade, listed in this discussion forum and elsewhere, to make Big Sur start up in less than the 4 to 5 minutes (!) it takes on my system, and on so many others featuring the same specifications (especially, the 1TB Fusion Drive with a 32 GB SSD blade). Many, if not all, owners of such an iMac, have reported and complained about similar boot times of up to five minutes before any application becomes responsive.

There are no login items in my user account, no suspect launch daemons or agents, no antivirus software, no cleaners, nothing... as I have proven elsewhere on this forum by publishing EtreCheck reports. Nothing is responsible for the unbearably long boot times, except Big Sur itself.

After three months and countless re-installs and debugging sessions, some of us have concluded that Big Sur is simply UNABLE to boot in less than four to five minutes on iMacs featuring a 32 GB SSD blade on the Fusion Drive.

I would like to know now if any of you who own an iMac featuring a 1TB Fusion Drive and a 32 GB SSD blade, were able to make Big Sur boot up in a timespan of 30 seconds or slightly more, whilst having a number of apps like Pages, Numbers, Keynote, iMovie, and Adobe Photoshop installed on their system.

For the sake of clarity, only one time I was able to have Big Sur boot up in about 20 to 30 seconds, ONLY right after a CLEAN install and BEFORE I installed the applications I have just mentioned. As soon as I added Pages, Numbers, Keynote, and iMove, the bootup time once again went up to 2,5 minutes or more. Having installed all the other apps (and be sure I don't have too many), Big Sur once again took between 4 and 5 minutes to load.

Apple Logo to login screen: after 1 minute

Menu Bar and Finder appearing: 40 seconds after desktop background appearing

Desktop items appearing: 10 - 15 seconds after Finder and Menu Bar appearing

Apps becoming available to launch without any delay: between 40 and 50 seconds later...

Apple totally ignores this problem, and it would surprise me if their engineers can actually come up with a solution for the simple reason that Big Sur seems to be too... "big" to have it load directly from the 32 GB SSD (of which actually only 28 GB are available to the OS) instead of having it load from the HDD part of the Fusion Drive upon startup. At every startup I heard my HDD working overtime, copying the OS to the faster part of the Fusion Drive.

Apple Support people tell me that they are unaware of this problem, and another user was told that 4 to 5 minutes "is a normal startup time" for such a system... (Wow!)

To SUMMARISE:

iMac 27″, macOS 10.15

Posted on Feb 24, 2021 4:44 AM

Top-ranking reply

Luis Sequeira1

Level 9

73,500 points

Posted on Feb 27, 2021 7:35 AM

It is not incompatible, but booting from this is indeed extremely slow.

And Catalina, even if it boots a little faster, is not fast either.

Recent versions of macOS pretty much require an SSD as a boot drive.

If you install macOS on an external SSD connected via USB3 it will be much much faster, and you can use your internal drive as additional storage.

Using a Fusion Drive like this, or even worse, just a rotating hard drive as the boot drive on any mac, is painful.

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68 replies

Roelof2

Level 1

8 points

Apr 27, 2021 5:17 AM in response to etresoft

My computer works perfect UNTIL BIGSUR. Please read my post carefully! And still working speedy with Catalina. I did not make assumptions! I tested!

Apr 27, 2021 6:38 AM in response to etresoft

Mr Etresoft,

I would like to thank you for proving me right. :-)

Apr 27, 2021 9:12 AM in response to Deep Sky Diver

I need to apologize. As it happens, there is no online Apple store in Greece.

Roelof2

Level 1

8 points

Aug 5, 2021 8:54 AM in response to etresoft

Please keep this tread alive so Apple has the opportunity to resolve the problem discussed.

etresoft

Level 9

56,692 points

Aug 5, 2021 9:36 AM in response to Roelof2

Roelof2 wrote:

Please keep this tread alive so Apple has the opportunity to resolve the problem discussed.

They already resolved it!

Feb 28, 2021 9:21 AM in response to Deep Sky Diver

About my HDD: Can you explain why a failing HDD would be super fast on Catalina and in top condition according to three disk tools?

My hard drive on my super old imac died yesterday. :(

Sort or irrelevant but it used to take about 10 seconds to boot into lion. By just looking at how fast it was, nobody would ever notice that it was just acting tough. D:,

But when I run yosemite on an external hard drive, It takes about 6 minutes to boot. Then the dock appears and I have to wait another 2 minutes for the menu bar to load. But luckily my applications load a bit faster.

You're hard drive being slow doesn't always mean that it's dying. That just means it's crap. You should get it replaced. Problem solved. Or if money is too expensive, then just don't use big sur.

Feb 28, 2021 1:37 PM in response to Deep Sky Diver

But thank you for making me laugh out loud...

No problem. ;)

But this thread really does need to control the heat. I know your iterated, but these people just want to help. So nobody really cares about a paid part of an application. (I honestly look for the paid parts so I can support the creator. But this is just a personal preference.) So let's take a deep breath and focus on what's important..., without killing each other. I'm leaving so best of luck to you. I hope you're problem gets solved.

Aug 19, 2021 5:58 AM in response to etresoft

That is incorrect because "they" did not tell anyone to follow the procedure that is the only way to get Big Sur up and running in a reasonable amount of boot time on a very large number of iMacs all over the world, some of which are not even Fusion Drive ones but are fully SSD-equipped... Some of us, users, found out that this procedure is the only one helping us out, and we found it out by using perseverance and logic, and largely thanks to this thread (!). But it's not a solution that I would like to recommend to anyone else but a person who has extensive knowledge of how to wipe Fusion Drive containers, volume groups, and reset the Fusion Drive in Terminal, as it obviously contains a lot of complicated steps, takes a lot of time, and surely isn't the procedure that Apple would usually want its users to follow... But this procedure does solve the problem, it does so without the need for any extra software or hardware to be purchased, and it even results in lightning-fast boot times, very fast startup times of very large apps, and speeding up any important OS process happening - and all that on Fusion Drive iMacs with a 1TB 7200 rpm HDD and a very tiny 32 GB SSD NVME blade!

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iMacs with 1TB Fusion Drive and 32 (28) GB SSD blade - unbearably slow boot times