Why does my 2019 27" iMac have identical listings in Storage for both a 1.03 TB SATA Disk and 1.03 TB Solid State PCI Express Drive?

Suggestion: If you click on the "All Volumes" button at the top right of Storage, you may or may not see confirmation like this:

This is on a 2017 iMac where the original hard drive element of the Fusion Drive was replaced by SSD by an Authorized Service Provider. If it has split, How to fix a split Fusion Drive is helpful, but I agree with Servant of Cats that it doesn't appear to be the problem (the figures being exactly the same). I find that erase + reinstall from Recovery, then migrate from a backup, sometimes speeds things up.

Dana and Rurocker:

If you want to try to determine why your Mac is slow do the following:

Download and run Etrecheck. 

Copy the report

and use the Additional Text button to paste the report in your reply.

Then we can examine the report and see if we can determine the cause of the problem.

Ruerocker: I suggest you start your own topic so as to get undivided attention to your problem and not get us confused with responses to Dana. Be sure to give your Mac model and year and post the report.

Most plausible explanation:

• There is some bug in the code that generates the storage report. The code is failing to present the Fusion Drive as a single logical volume, and is generating reports for each component. When it goes to calculate the storage statistics for each component, it is going through paths that do correctly understand that the volume is a Fusion Drive. So both paths calculate the exact same answer; which gets displayed twice.

Less plausible one:

• Somehow, the Fusion Drive got split, and there are now two volumes. One was cloned to the other (somehow) – and so the storage statistics are identical (for now). This seems unlikely because you have 476.32 GB used and Apple never made Fusion Drives with more than 128 GB of SSD storage. On 2019 iMacs which had 1 TB Fusion Drives, there is only 32 GB of SSD storage.

Hi, I'm seeing the exact same thing. The mac has also been very slow and and I'm not sure if this has always been this way or whether whatever caused the drives to be seen as the two individual drives is the cause.

@Dana, Have you had any luck with this issue?

Note that you can get 1 TB third-party blade SSDs for your Mac. It would be physically possible for your Mac to have both a 1 TB internal HDD and a 1 TB internal SSD that were not part of a Fusion Drive.

I think if you had split the Fusion Drive, upgraded your Mac's internal SSD, and set up the new SSD using a clone backup of the contents of the old HDD, you'd know it …

https://eshop.macsales.com/shop/ssd/owc/imac-27-inch/2013-2019

I have the same problem on iMac 21,5 2019 with Fusion Drive. The problem started when I heard the HD started running all the time like it was reading and writing Data after installing one of the versions of Sonoma. I am not sure which update that was. I am on 14.4.1

I went thru the process of How to fix a split Fusion Drive. At the end of the procedure I had the same out come.

I am going replace the SSD that came with it and install a 1TB ssd. Hopefully that will fix it.

Dues that Mac, by any chance, have a Fusion Drive?