Four little utilities now compatible with macOS Tahoes, covering repair of Finder aliases, creating test sparse files and checking special file types, looking up UTI types, and analysing language.
sparse file
Read-write and VM disk images are created and maintained differently, but they can both be APFS sparse files. Explanation of their creation and maintenance.
How read-write disk images and those used in Apple silicon virtual machines use sparse file format to save space on disk.
How do clone files and sparse files cope with being backed up and restored? Can they save space in iCloud Drive? Some of these answers may surprise.
Deleting clone files saves no space, but converting copies into clones could free up plenty of storage. Sparse files can also be highly efficient, and squeeze 285 GB into just 16.5 GB.
Deciding which file system to use for hard disks can be difficult. Here are the advantages and disadvantages explained in detail, for HFS+ and APFS.
The only disk images of varying size used to be sparse bundles and sparse disk images. Now plain read-write disk images can also vary in the disk space they take, as explained here.
When do sparse files explode to full size, and how could you preserve them in transit? Can you copy clones or snapshots? How to preserve extended attributes?
What can cause low copy speeds for very large and possibly sparse files, such as VMs? Causes explained, and tools you can use to discover why.
Sparse files are now common among databases, disk images, and virtual machines. How they work in APFS, how they’re created, and how they can explode.
The Eclectic Light Company 