Change size of disk partitions

[Gren]

Until today I used a 2TB mains powered external drive for regular Time Machine backups and weekly SuperDuper manual updates, partitioned equally.

In an effort to save some energy I have now transferred the Time Machine backups to a solid-state drive and renamed the partition “Media” where I have stored old photos and music. This is so I can leave the drive switched off until I need to update SuperDuper or access the media.

While it’s not necessary at the moment I want to reduce the size of the Media partition to 500 Gb and increase the SuperDuper to 1.5 Tb, I have tried to do this in Disk Utility but it will not allow me to. If I reduce the Media partition it creates a new Untitled partition and will not allow me to increase the SuperDuper partition.

Can anyone tell me how to achieve this please? Sorry for the long question.

Screenshot attached, thanks.

 

[MacInWin]

How is "Media" formatted? The SuperDuper appears to be in an APFS container. APFS dynamically manages the space between all containers. I think the easiest way to accomplish what you want could be to create a new Volume inside Container disk4 and name it Media, then copy everything from the original Media to the new Media, test it to confirm everything is there, and then do away with the old Media. Then adjust the size of Container disk4 to be the entire disk. From that point, Media and SuperDuper will dynamically share the space remaining on the drive.

Of course, before doing any of this, make copies of everything. Messing about with partitions can have bad results if you make a mistake.

Unless you are using SuperDuper for historical storage, another way to get where you want is to simply erase and reformat the entire drive as APFS, create one Container with two Volumes, one Media and the other SuperDuper, make a new SD backup to SuperDuper and then copy what you want to Media. That gets you a nice clean drive with each Volume taking as much as it needs from the free space in the Container.

 

[Gren]

How is "Media" formatted? The SuperDuper appears to be in an APFS container. APFS dynamically manages the space between all containers. I think the easiest way to accomplish what you want could be to create a new Volume inside Container disk4 and name it Media, then copy everything from the original Media to the new Media, test it to confirm everything is there, and then do away with the old Media. Then adjust the size of Container disk4 to be the entire disk. From that point, Media and SuperDuper will dynamically share the space remaining on the drive.

Of course, before doing any of this, make copies of everything. Messing about with partitions can have bad results if you make a mistake.

Unless you are using SuperDuper for historical storage, another way to get where you want is to simply erase and reformat the entire drive as APFS, create one Container with two Volumes, one Media and the other SuperDuper, make a new SD backup to SuperDuper and then copy what you want to Media. That gets you a nice clean drive with each Volume taking as much as it needs from the free space in the Container.

Thanks, I'll try option 1 first.
Two questions - how do I "do away with the old Media" and "adjust the size of Container disk4 to be the entire disk." Neither seems obvious, thanks.
Gren

 

[pm-r]

While it’s not necessary at the moment I want to reduce the size of the Media partition to 500 Gb and increase the SuperDuper to 1.5 Tb, I have tried to do this in Disk Utility but it will not allow me to. If I reduce the Media partition it creates a new Untitled partition and will not allow me to increase the SuperDuper partition.

Can anyone tell me how to achieve this please? Sorry for the long question.

iPartition for Mac.

iPartition for Mac
and various other download sites.

It makes Disk Utility look pretty feeble and it's a pleasure to use. But I haven't used the latest version... Double check it's compatibility with your Mac OS version...

PS: it's best to have a backup you can fall back on for use if need be...




- Patrick
=======

 

[MacInWin]

Not obvious, but have a read of this from Apple:

Partition a physical disk in Disk Utility on Mac

In Disk Utility on your Mac, add, delete, erase, or enlarge a partition on a storage device.

support.apple.com

Note that it says:

To enlarge a volume, you must delete the volume that comes after it on the device, then move the end point of the volume you want to enlarge into the freed space. You can’t enlarge the last volume on a device.

I added the emphases. From your screenshot, the SuperDuper in the APFS Container appears to be the last volume on the device, so you may not be able to enlarge it. What I would do is to follow my second approach, to copy what you want from Media and SuperDuper to some other drive, erase and reformat/repartition the entire drive into one container in APFS, then add two volumes, one named Media and one SuperDuper and then copy back to those two from the place you copied them to for saving. If you don't mind restarting with a new SD backup, you would just have to move Media somewhere temporarily, erase, reformat/repartion the drive, create the container and volumes and then do another SD backup into the SuperDuper volume. The article has all of the steps to do that.

Given that the way APFS works is that the Volumes share the free space dynamically, as I said, both Media and SuperDuper will show the same amount of free space, and each will take from that space as needed until the Container is full. But don't go to "full" because you should leave workspace in the Container, about 15-20%, for the OS to work with. You can safely make the Container the full size of the hardware device, but don't fill up the Container itself.

You can stop here if you want. What follows is a brief discussion of how Drive/Container/Volumes work together.

Think of a device, a drive, as a big box. When you create a Container, you set aside part of that box with a fixed size. It is most logical to just have one, but you could make two, or more, Containers. In the old drive format, HFS+ (MacOS Extended Journaled), the size of the Containers were fixed and they did not share the free space on the drive with the other Container. Now,in APFS, in the Container are some partially filled balloons, called Volumes, that look like drives when mounted on macOS. But they share the open space in the Container. So when one of the balloons gets more air and grows, it takes up some of the free space, leaving both it and the other balloons less free space. But you, the user, didn't have to make any changes, the free space is shared automatically. That's the benefit of APFS. Not only is it optimized for faster operation with SSDs, it reduces the work required to use free space efficiently.

iPartition for Mac.

iPartition for Mac
and various other download sites.

It makes Disk Utility look pretty feeble and it's a pleasure to use. But I haven't used the latest version... Double check it's compatibility with your Mac OS version...




- Patrick
=======

It's not compatible with APFS, I think.

 

[pm-r]

It's not compatible with APFS, I think.

Thanks Jake, I was afraid of that but wasn't sure but not surprising as the Developers dropped further development a little while ago as Apple would not release any details about their APFS format etc...
Rather unfortunate but it seems to be the state of many third party developer Mac things these days... :-(


- Patrick
=======

 

[Gren]

Not obvious, but have a read of this from Apple:

Partition a physical disk in Disk Utility on Mac

In Disk Utility on your Mac, add, delete, erase, or enlarge a partition on a storage device.

support.apple.com

Note that it says:


I added the emphases. From your screenshot, the SuperDuper in the APFS Container appears to be the last volume on the device, so you may not be able to enlarge it. What I would do is to follow my second approach, to copy what you want from Media and SuperDuper to some other drive, erase and reformat/repartition the entire drive into one container in APFS, then add two volumes, one named Media and one SuperDuper and then copy back to those two from the place you copied them to for saving. If you don't mind restarting with a new SD backup, you would just have to move Media somewhere temporarily, erase, reformat/repartion the drive, create the container and volumes and then do another SD backup into the SuperDuper volume. The article has all of the steps to do that.

Given that the way APFS works is that the Volumes share the free space dynamically, as I said, both Media and SuperDuper will show the same amount of free space, and each will take from that space as needed until the Container is full. But don't go to "full" because you should leave workspace in the Container, about 15-20%, for the OS to work with. You can safely make the Container the full size of the hardware device, but don't fill up the Container itself.

You can stop here if you want. What follows is a brief discussion of how Drive/Container/Volumes work together.

Think of a device, a drive, as a big box. When you create a Container, you set aside part of that box with a fixed size. It is most logical to just have one, but you could make two, or more, Containers. In the old drive format, HFS+ (MacOS Extended Journaled), the size of the Containers were fixed and they did not share the free space on the drive with the other Container. Now,in APFS, in the Container are some partially filled balloons, called Volumes, that look like drives when mounted on macOS. But they share the open space in the Container. So when one of the balloons gets more air and grows, it takes up some of the free space, leaving both it and the other balloons less free space. But you, the user, didn't have to make any changes, the free space is shared automatically. That's the benefit of APFS. Not only is it optimized for faster operation with SSDs, it reduces the work required to use free space efficiently.


It's not compatible with APFS, I think.

Thanks Jake

I have gone with your preferred "nuclear" option and reformatted the drive. After a couple of false starts where I wound up with multiple partitions for some reason it has worked. I have copied the photos and music to Media and SuperDuper is currently performing a new backup, about two-thirds done after nearly four hours!

I really appreciate the time and trouble you took to help and educate me in the arcane mysteries of containers and volumes. You were very helpful and patient, many thanks.

Gren

 

[MacInWin]

Glad to help, Gren.