External Disk Partition Management

Hello all. I'm wondering if someone could enlighten me as to how to manage/move/edit partitions without losing data on accompanying partitions please? You'll see from the screenshots that I have a disk containing ToshibaStorage and ToshibaTM partitions. And you'll see the lone disk Lacie. I would like to remove ToshibaTM without affecting ToshibaStorage's data if at all possible. And then setup a new TM partition on the Lacie without affecting its original data. Is this possible? I know nothing along these lines, I can just manage to format a new/blank disk as needed for partitions like this but I'd rather not have to move several TB of data back and forth just to restructure, if possible. TIA.

Mac mini, macOS 14.3

Posted on Feb 18, 2024 9:33 AM

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22 replies

Feb 18, 2024 9:54 AM in response to rothnd

rothnd wrote:

...I would like to remove ToshibaTM without affecting ToshibaStorage's data if at all possible. And then setup a new TM partition on the Lacie without affecting its original data. Is this possible?

Ok, a bit of background may help. Your LaCie drive is currently formatted with HFS+; whereas, your Toshiba is formatted with APFS. The big difference is what used to be called "partitions" in HFS+ is now called "containers." But there is one significant additional difference: APFS containers are dynamic. Also, you can easily create multiple volumes within an APFS container.


That means, it is far easier, when you have existing data on a drive, to add container, than partitions. The latter being "fixed" in size.


In your case, ToshibaTM is an APFS volume inside the disk11 container. You can simply erase it using the Disk Utility if you no longer want it. This will not affect ToshibaStorage.


However, for your LaCie, you would first have to create a new partition from the existing one. The key is how much data is currently taking up storage space in the existing partition. You would want the new TM partition to have 2-3x the storage capacity of the Macs that you are backing up with Time Machine (of course, I'm assuming that the TM label is what this is meant for.) If the LaCie does not have adequate space left, this will not work.


Let us know how you would like to proceed. Also, if you don't mind, please take a screen shot of ToshibaStorage. Based on what you have provided, it appears to be a second APFS container on Drive Dock 1.

Feb 18, 2024 10:22 AM in response to rothnd

Gotcha. To make sure I fully understand your drive configurations, please provide screenshots of the results of these two commands in the Terminal app. Be sure to run them separately. In case you are not familiar with using the Terminal app, to exit the Terminal, just enter: exit , and then press return.


  • diskutil list external
  • diskutil ap list

Feb 18, 2024 11:46 AM in response to rothnd

Thank you. While I get a moment to "digest" those, I would like to offer two suggestions before we start:

  1. If you have a "spare" external drive, we will want to keep that handy to make backups. This is especially important if any of those drives, we are going to work on, have data that is critical to you. If you don't have a spare, now would be a good time to consider getting one.
  2. I am going to provide you with a few Apple Support articles. I would like for you to just READ them at this point. This should get you familiar (in case you're not) on how to use the Disk Utility to create or erase partitions, container, and volumes.


Oh, and to answer your earlier point about TM reformatting a drive for APFS. That is true in a number of cases. Nothing to be concerned about. As you may know, HFS+ is still the preferred format for hard disk drives, with APFS for SSDs ... but APFS can be used with HDDs without any performance penalties.


Ref:

Feb 18, 2024 12:24 PM in response to rothnd

... and while I figure out the best course of action, here is my initial analysis of your drives based on the screenshots you provided.


  • disk3 is your Mac’s internal drive. It is formatted in APFS with the appropriate APFS Volumes for macOS.
  • disk4 is an external 10 TB drive formatted in HFS+. This would be your LaCie drive.
  • disk6 & disk7 are external two 5.0 TB drives configured as a RAID0 making up a virtual disk8, named Little TV. This would be your Seagate Portable Media drives.
  • disk9 is an external 16.0 TB drive with, what looks like, both an APFS Container that is making up disk11 & a HFS+ Partition. Not sure how this happened. This would be your Dual Drive Dock 1 Media drive
  • disk10 is an external 16.0 TB drive with a single HFS+ Partition with a single HFS+ Volume, called TshibaMedia. This would be your Dual Drive Dock 2 Media drive.
  • disk11 has a single 2.0 TB APFS Container with a single APFS Volume, named ToshibaTM which appears to be used for Time Machine. disk11 is the only external drive with APFS formatting


I do have a few questions still ... sorry:

  • How much free storage space is still available on the LaCie drive? Again, you will want to have, at least, 2-3x the storage space as what your Mac mini's internal drive has for Time Machine backups.
  • Do you care if we delete the existing ToshibaTM volume & it data (TM backups)? TM may have issues with using another "drive" for backups to continue with the existing one that is moved.

Feb 18, 2024 1:05 PM in response to rothnd

Thanks. Sorry for any repetition, I just want to be sure I don't steer you in the wrong direction.


That should be enough storage on the LaCie for a TM backup partition. The first article I provided you with a link to is how you would go about resizing your LaCie current partition to make room for another one. After doing so, you can format the TM partition in either HFS+ or APFS. It won't matter, as TM will "re-format" it again for its purpose.


Once that is done, you should be able to point TM to make its backups to that new partition on the LaCie.

Feb 18, 2024 1:34 PM in response to rothnd

rothnd wrote:

I think I managed the Lacie change. Have to ask about Toshiba. Should I remove just the volume ToshibaTM or it’s container (disk11) and thereby both container and volume?

That will be up to you. Since this drive has a single Container with one Volume, you can simply erase the volume. When you decide to use this drive for another purpose, it will already have the Container & Volume available to use. Remember, with APFS, these are dynamically sizable so they don't take up much real estate when not used.

Feb 18, 2024 1:49 PM in response to rothnd

Well, if it was me, I prefer to start with a "clean slate." Since you already have backups, my choice would be to completely configure it with a single APFS Container & single APFS Volume, which Disk Utility will do in one step.


You will then have a "clean" drive to do whatever you want with it. One note. If you plan on using a drive for TM, it has been my experience that you want to dedicate a drive for this and not create either additional Containers or Volumes for this purpose. Why,? Because of, at least, two reasons: 1) You will the maximum amount of storage space for TM to do its thing, and 2) You don't have to deal with the issues you are seeing now.

Feb 18, 2024 10:05 AM in response to Tesserax

I appreciate the initial info! Apparently though, Storage is an HFS+ partition. I believe TM is responsible for creating that APFS container for TM. Don’t know how else to explain that…

Yes, I would like to proceed, in a careful and well thought out manner. If I’m doing something bizarre I would definitely like to know that too!! Thanks!

Feb 18, 2024 12:49 PM in response to Tesserax

Sounds awesome! In terms of external drives, these are basically backed up to each other so.. I don’t think a need another drive for that purpose just yet.


That was my original understanding APFS vs HFS+, SSD vs HDD. So I don’t know what “best practice” would be, but I’d like to future proof as much as possible for the data set gets even larger. So like if all HDD to APFS now helps in that regard I’m willing :)


OK then, I will get to my reading, thank you for all!

Feb 18, 2024 1:10 PM in response to Tesserax

I think I can follow that yea, just finished reading it. About the 16 (14/2) Toshiba - how best to erase the 2 TM and enlarge the 14 Storage without affecting data on Storage?


Would it be wiser to just start over in these early (ier) days and format all of them to APFS; basically start over and just copy data for days lol?

Feb 18, 2024 1:53 PM in response to Tesserax

Yea that sounds better to me too. But. I kinda have to do it this way with TM for now. Like 6 drives in use, don’t have the board/space for another drive right now..


so clean slate it. 1 drive = 1 container = 1 volume? Except my TM fiasco for right now - 1 drive = 1 container = 2 volumes *or* 1 drive 2 containers 2 volumes? I would guess one container but want to check.

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External Disk Partition Management

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