Partitioning Software

Solution 1:

iPartition (only ≤ OS X 10.13)

iPartition is now legacy. The company, Coriolis, finally closed in 2019. There is still a (now essentially freeware/donationware) version of iPartition available for download, but only good to OS X 10.13 for pre CoreStorage disks.

It allows you to move and resize partitions without deleting any data. It also works for Boot Camp volumes and other PC disks.

With iPartition, resizing a partition is as simple as selecting it, grabbing the resize handle and dragging. Not only that, but if you have several operations to perform, iPartition lets you queue them up and run them one after another, so you can have a cup of coffee while iPartition works. This feature, coupled with iPartition’s ability to automatically rearrange your existing partitions when necessary, makes iPartition the easiest partitioning tool that you’ll ever use.

Solution 2:

Disk Utility can do non-destructive partitioning (add or remove) but cannot move partitions.

This functionality was added in Lion, I believe.

The key is to click on the right thing. Note the following image:

1. You have to select the 'root' of the drive, not any of the existing partitions (see arrow #1)

2. Click on 'Partition'

3. You can change the current partition scheme my selecting the drop down.

4. If you select one of the existing partitions, you can use the +/- buttons to delete a partition or break it into a smaller size.

I have done this many times and have only had it fail on me once, early in the life of the functionality, however that one time did leave me with an unusable drive that I had to reformat and restore from backup.

Which is my way of saying: make sure you have a verified backup before you start mucking around with partitions, regardless of which app you use.

Solution 3:

Stellar Partition Manager

Stellar Partition Manager allows you to create, delete, resize, hide, and unhide partitions on your Mac.

Efficiently manages partitions on Mac hard drives including the BOOT volume without causing data loss.

Professional Mac volume manager that allows you to perform basic partitioning operations, such as creating, deleting, resizing, formatting, and hiding/revealing a partition.

• A complete Mac Partition Manager utility
• Creates new partition(s) on Mac hard drive
• Resizes, formats, or deletes existing partitions
• Resizes Mac partition by optimizing the free space
• Resizes partition that Disk Utility fails to resize
• Performs batch operations preventing the risk of data loss
• Compatible with the latest OS X Mavericks

Solution 4:

Paragon Hard Disk Manager

There's a new kid on the block.
iPartition does not support Core Storage (Fusion Drive and File Vault 2 both use this volume format) & hasn't had an update in a long time.

Features - from their web site -

• Partitioning in El Capitan/Sierra
  In the latest OS X layout of the system disk is not allowed to modify by any third-party application until System Integrity Protection or SIP is deactivated, which is not an option for many users. Our program detects an active SIP and prompts to create and use a special bootable USB-flash stick or external disk to do drive partitioning.
• Redistribute free space
  Increases free space on one partition by utilizing the unused space on the adjacent partition.
• Resize/Move partition Enables to move the left or right border of the selected partition, thus not only resizing, but moving it on the disk.
• Undelete partition
  Helps to find and recover any lost or accidentally deleted partition.
• Convert partition table
  Helps to do non-destructive conversion between GPT (GUID Partition Table), MBR (Master Boot Record) or a hybrid GPT+MBR partition tables.
• Change partition properties
  Mount or unmount a partition, set it active or inactive, change its identifier (ID), etc.
• Rich file system support
  Create, format, resize, change properties of HFS+, NTFS, ExtFS, FAT and exFAT partitions.
• Resize Boot Camp
  Redistributes free space between Mac OS X and Windows OS volumes in Boot Camp with minimal effort.
• Easy Windows OS migration
  Through restore of a Boot Camp image on a different Mac computer.
• Fix Windows boot issues
  If a Windows OS doesn’t boot after replacing a failed hardware device or you’ve got any other boot issue resulted from a human or program error, or a boot virus activity, first try our boot repair tools before taking more radical actions.

There are also comprehensive backup/restore options.