Excuse me if this is not the correct forum, but it seems an application would be needed to re-size partitions. So, here goes.

I understand that Disk Utility (DU), especially for recent versions of the Mac OS (Catalina and Big Sur), is the only reliable program that can be used for re-sizing partitions. But a couple of years ago, I had issues in trying to do that task. And in reading about using DU just a little while ago, it seems to indicate that to resize a partition, the "next" one needs to be deleted first. That seems counter-intuitive, at least for my situation.

I have 2 external Samsung 850 Pro 512 gig SSDs. For both of them, there are 3 partitions: 2 of the partitions, each 100 Gig in Size and formatted as APFS, are used for the SuperDuper! backups for each of my Catalina-based Macs. One of them, the third partition, also formatted as APFS, contains various files, and is a little over 300 gig in size. For it, I can get rid of all but 53 gig of information, and thus will have about 247 gig free. For the other one, formatted as HFS+ and also about 300 gig in size, I can get rid of 53 gig, and that amount takes up over 97%. That partition will then have about 3 or 4 gig left.and thus about 296 gig free.

In preparation for Big Sur, I'll need to increase the sizes of the two backup partitions (looks like those will be for Carbon Copy Cloner) to about 150 gig each. Hence, mathematically that should be dooable, given how much "free space" there will be on each third partition.

I know that one way I could do this is to 1) copy all that "smaller" information from each of the "miscellaneous" partitions to flash drives (I have one that is 256 gig in size), 2) Erase and Format each SSD, and 3) create 3 new partitions (2 of them would be the backup partitions each 150 gig in size, formatted as APFS). But, doing that runs the risk of having no backups in the very short term. I would much prefer the ability to just resize the 2 backup partitions, after making the necessary room by removing what I mentioned above from each miscellaneous partition.

Would appreciate any advice, assistance, etc. for this exercise.

Last edited by MartyByrde; 02/15/21 11:55 PM.