downgrading from catalina to mojave issue

[aliendoughnut]

i have recently downgraded my os on my imac back to mojave after discovering some of my apps i need don't work. after downgrading i now have 2 hdds on my desktop with the same name? is there a way to repair this and go back to having just the 1?

 

[Rod]

So I might as well beat everyone else and ask; how did you downgrade to Mojave?
Because Apple doesn't support retrograde OS installation the process of going back to a previous macOS normally requires you to erase the internal drive first while booted from another source such as a Bootable clone or Bootable macOS installer. I the feeling you may not have done this?


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[aliendoughnut]

i downloaded the os from the app store which appeared in my applications. i the then used this to create a bootable drive on a usb stick. used this to reinstall mojave then used my time machine to reinstall my back up file. all is well apart from having 2 hdds with the same name showing on my desktop. i did format the hd but there were 2 showing i cant remember what they were called but one had the name data which is the one i selected

 

[aliendoughnut]

is there a way to merge the 2 hdds so i only have the one again and then i can repeat the process?

 

[Raz0rEdge]

OK, these are the steps you should follow.

1) Boot from the Mojave USB stick, remove all the drives, re-create a single partition and do a fresh install of Mojave. DO NOT RESTORE ANYTHING.
2) Once installation of Mojave is complete, power down the Mac.
3) While powering up the Mac, hold down CMD+r to enter the Recovery Console.
4) From the macOS Utilities window choose to restore a time machine backup and point it at the backup and the only HD you should have.

When finished restart the machine and it should boot into Mojave with all of your data intact and there should likely only be a single HD.

Reference this article and the section titled Restore both macOS and your files.

 

[aliendoughnut]

thanks for the reply when i am in disk utility what is the procedure for doing this? is is just a case of pressing the - button on the volume for each hdd to delete it and then use the + to create a new one? i dont want to delete until i know what i am doing

 

[Raz0rEdge]

These are the steps: How to erase a disk for Mac - Apple Support

 

[aliendoughnut]

a couple if screen shots to show the 2 hdds one says version 10.5 and the other is version 10.14.6 so looks like catalina is one of them

 

[Rod]

It is the Disk you need to erase, not the volumes. This will get rid of the two duplicate HD's (volumes). See the second illustration in the link posted in the above post.


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[Rod]

However you had not mentioned until now that you had a fusion drive. Here I must defer to the other members as I have no experience with fusion drives.
I'm sure that the principal's will remain the same but there may be specific differences in executing the process.
This is why the first thing we usually ask people are the details of their device. Not that there are many fusion drives left out there.
It appears you have created a second volume that is Catalina while the original remains Mojave.
If you open the first HD can you run the applications in question as before?


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[aliendoughnut]

thanks i have added a screenshot of the disk utility in recovery mode showing 2 internal hdds and not sure what the disk image mac os base system is?

 

[MacInWin]

I have not upgraded to Catalina, but I have read that Catalina creates two partitions on the boot drive. One holds the system files and has a higher level of security. The other holds the user data and is labelled as such. What I think happened is that in trying to roll back, you did not reformat the drive, which left it with two partitions. You said one was labelled "data" and you renamed, which is how you ended up with two with the same name.

Assuming you don't care about what is on either of those drives, the best thing to do is to boot from a bootable external drive and run Disk Utility to reformat the drive entirely at the. highest level using APFS format. The reinstall whatever version you want to that empty drive and restore from your backup.

 

[chscag]

I have not upgraded to Catalina, but I have read that Catalina creates two partitions on the boot drive.

I can verify what Jake said above. The two partitions appear on the desktop and look like separate hard drives. I noticed that the first time I ran the beta and it is likewise present in the final version. If that is an annoyance, just go into Finder preferences and remove the option for drives to appear on the desktop. I don't believe that has anything to do with you having a Fusion drive.

 

[aliendoughnut]

I have not upgraded to Catalina, but I have read that Catalina creates two partitions on the boot drive. One holds the system files and has a higher level of security. The other holds the user data and is labelled as such. What I think happened is that in trying to roll back, you did not reformat the drive, which left it with two partitions. You said one was labelled "data" and you renamed, which is how you ended up with two with the same name.

Assuming you don't care about what is on either of those drives, the best thing to do is to boot from a bootable external drive and run Disk Utility to reformat the drive entirely at the. highest level using APFS format. The reinstall whatever version you want to that empty drive and restore from your backup.

i dont seem to have the option to go a level higher than the the 2 drives as you can see in the screenshot showing the drives in recovery mode in disk utility vs the screen shot showing the drives by just showing disk utility in the normal mac boot up and in that mode the option to erase the fusion drive is greyed out but this drive does not show in recovery mode only the 2 hdds. i have the option to erase the hdds but not to reformat the fusion drive. Not sure why the views are different in the different modes sorry i have limited experience with disk utility. not sure what my next step would be

 

[MacInWin]

i dont seem to have the option to go a level higher than the the 2 drives as you can see in the screenshot showing the drives in recovery mode in disk utility vs the screen shot showing the drives by just showing disk utility in the normal mac boot up and in that mode the option to erase the fusion drive is greyed out but this drive does not show in recovery mode only the 2 hdds

Let me see if I can parse out this to make sure I understand. If you click on the "View" box at the top of Disk Utility, there should be some options there. One is "Show only volumes" and the other is "Show all devices." I would bet that "Show only Volumes" is checked. Change to the other option and the fusion drive should show up with the two volumes indented below it. I give up on the rest of the sentence, I can't make heads or tails out of what you are trying to say, sorry. The reason the fusion drive is greyed out is that you cannot format the boot drive while booted from it. So you have to boot from recovery, or an external drive to get erase access to the internal fusion drive itself.

 

[ferrarr]

+1 for what MacInWin said about “Show all devices”, in Disk Utility.

Another thing you can do is just move the drive icon you don’t want displayed on the Desktop, into the Trash. Then you will only have the one icon, you’d o want, still on the Desktop.

I don’t have my drive icons displayed on my Desktop, but I still don’t have 2 in the Finder sidebar. I’ll have to look into that when I’m at my Mac.


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[aliendoughnut]

Let me see if I can parse out this to make sure I understand. If you click on the "View" box at the top of Disk Utility, there should be some options there. One is "Show only volumes" and the other is "Show all devices." I would bet that "Show only Volumes" is checked. Change to the other option and the fusion drive should show up with the two volumes indented below it. I give up on the rest of the sentence, I can't make heads or tails out of what you are trying to say, sorry. The reason the fusion drive is greyed out is that you cannot format the boot drive while booted from it. So you have to boot from recovery, or an external drive to get erase access to the internal fusion drive itself.

Thanks for the info i will check that option to show all devices while in recovery mode