Macintosh HD - Data addition after updating.

[the_color_orange]

Hi! I just updated my MacBook Pro to macOS Catalina. After installation, I noticed that MONIT was showing Machintosh - Data in addition to the normal Macintosh HD partition. I checked on Disk Utility right after and saw it wasn't MONIT showing the wrong drives. I now have this partition Macintosh HD - Data. It is screwing up my Storage stats and honestly feel it could potentially be bad. Anyone have any clue what this is or if it is normal? Note that I was not on Beta and just updated today.

 

[Mike Boreham]

Don't know what MONIT is but after upgrading to Catalina you will have two volumes: Macintosh HD and Macintosh HD-data. The first is the system volume and is read only, the second is all your data. They appear as one volume on the Desktop but as separate volumes in Disk Utility.

 

[the_color_orange]

Ohh okay. That makes sense. I wonder why they split it or are showing them like that.

 

[Mike Boreham]

Ohh okay. That makes sense. I wonder why they split it or are showing them like that.

Security, the System Volume is read only so less likely to get corrupted etc.

 

[Huntn]

I just installed Catalina today on my MBP. I've got both of those drives (Macintosh HD+ Macintosh HD-Data and using the "get info" screen, they show the identical total and used capacity content size wise. I assume they are showing the same data? I read that one is read only, but it seems strange they would both show the same used volume. Plus when I look down at the file structure they seem to be mirror images of each other.
I've also got a couple of folders under Users>Shared>Relocated Items> divided into >Security and >Configuration. Can anyone explain that? Thanks!

 

[DeltaMac]

That's part of what you get with the APFS format. Additional volumes can share the same total space.
I have two added volumes, in addition to the Catalina system, with two other bootable systems, one with High Sierra, and the other with Mojave, all in the same "Container". So, 3 different bootable systems, independent on their volumes, each sharing space on that container.
(I don't understand the tech details about how that works, but that's what it does - all volumes in a container can share the same total space. )

The main volume (Macintosh HD, as an example) is read-only, and is where all of the system-installed files are stored. You may not easily modify that volume.
The (Macintosh HD-data) volume that is added is read/write, and has all your own files and apps.

 

[dsemf]

I just installed Catalina today on my MBP. I've got both of those drives (Macintosh HD+ Macintosh HD-Data and using the "get info" screen, they show the identical total and used capacity content size wise. I assume they are showing the same data? I read that one is read only, but it seems strange they would both show the same used volume. Plus when I look down at the file structure they seem to be mirror images of each other.
I've also got a couple of folders under Users>Shared>Relocated Items> divided into >Security and >Configuration. Can anyone explain that? Thanks!

Take a look at my posting from earlier today. A mild OCD Partition / Volume Rant

It has an image which shows the new volume arrangements for Catalina.

In summary, the OS is installed in a read only volume, such as Macintosh HD and the non OS data is in a read/write volume, such as Macintosh HD - Data. These are both in a volume group which makes them look like a single volume when using Finder.

The relocated items are files that could not be handled by the install and need to be manually dealt with. There should be a document that explains the purpose of relocated items.

DS

 

[Huntn]

Take a look at my posting from earlier today. A mild OCD Partition / Volume Rant

It has an image which shows the new volume arrangements for Catalina.

In summary, the OS is installed in a read only volume, such as Macintosh HD and the non OS data is in a read/write volume, such as Macintosh HD - Data. These are both in a volume group which makes them look like a single volume when using Finder.

The relocated items are files that could not be handled by the install and need to be manually dealt with. There should be a document that explains the purpose of relocated items.

DS

I’ll take a look at this tomorrow. Thanks.

What confuses me is that I want to take the two folders out of the relocated folder, but they are seen in both of these HDs. In fact everything looks mirrored, so which folders should I be making changes to, and after I make the changes, will both folders still mirror each other? It’s confusing until I work with it a bit more.

 

[Huntn]

That's part of what you get with the APFS format. Additional volumes can share the same total space.
I have two added volumes, in addition to the Catalina system, with two other bootable systems, one with High Sierra, and the other with Mojave, all in the same "Container". So, 3 different bootable systems, independent on their volumes, each sharing space on that container.
(I don't understand the tech details about how that works, but that's what it does - all volumes in a container can share the same total space. )

The main volume (Macintosh HD, as an example) is read-only, and is where all of the system-installed files are stored. You may not easily modify that volume.
The (Macintosh HD-data) volume that is added is read/write, and has all your own files and apps.

But my first cursory glance they both show the same folders, sub-folders, and same content. For example in the Security folder. I have the two folders I mentioned, both consist of my data, one is called Mac Sync, and the other is Mac Sync Frequent. I keep them both synced to an external hard drive. now I’m wondering if my synch program is still functional or if its setting will need to be adjusted. I’ll check that tomorrow too.

 

[DeltaMac]

If you return to the folders on the two volumes, you will find that the folder contents are different, significantly so. Start with the System folders on the two respective volumes, particularly /System/Library.
You will find there are probably NO applications in Macintosh HD/Applications (which are now in Macintosh HD/System/Applications) -- and all of YOUR apps are found in Macintosh - Data/Appplications.

 

[Menujusenja]

Got a lot drive after installed Catalina, this is normal? I try to clean install 3 times, Right now on my desktop show 4 drive. So confusing!

 

[the_color_orange]

Got a lot drive after installed Catalina, this is normal? I try to clean install 3 times, Right now on my desktop show 4 drive. So confusing!

That has too many Data drives! Doesn’t seem right. What I’ve understood there’s the OS read only drive and the writable user drive. I think it might be an APFS issue.

 

[Menujusenja]

That has too many Data drives! Doesn’t seem right. What I’ve understood there’s the OS read only drive and the writable user drive. I think it might be an APFS issue.

Waiting Apple support replying my DM, i will update in here!

 

[IowaLynn]

The " - Data" volume (cluster) was created from your old MacintoshHD and then "firmlink" to point to the new read-only system cluster volume. Safari and 3rd party apps are left on - Data, where read/write is req'd and also so that Safari can be updated without refreshing the entire system.

The Catalina installer would convert your drive from HFS+ to APFS unless it was already, and update the Mac's firmware.

With more than one " - Data" volume it would seem the installs failed or the disk drive was not successful in converting - and needs to be erased. Instead it created a new Data volume each time.