Snapshots made by Time Machine and tmutil should be purgeable, although sometimes they won’t purge, and aren’t shown reliably as purgeable space. An exploration of bugs and missing documentation.
Time Machine
If you leave your Mac running overnight, but not sleeping, what does it do? Does it perform maintenance tasks that it would otherwise have to do during the day?
Nine days of measurements of used space on a Time Machine backup storage drive. What does DeltaFree predict for its lifetime? How does used space change in containers in the internal SSD?
To work out how long you’ll be able to use your present backup storage, you need to know how much space is free now, and the rate at which free space is being used by further backups. This app can forecast that, and more.
Does your backup storage really need to be twice the capacity of your Mac’s internal SSD? If you’re already backing it up you can estimate the size required more accurately, as given here.
Every computer system needs a backup strategy to cope with different scales and types of disaster. How to work out what needs to be preserved, and how to do about reducing the risk of data loss.
Support for encrypted HFS+ ends next year in macOS 28. Does that also affect encrypted disk images? Could you use in situ conversion to APFS Encrypted on old Time Machine backups?
DAS and CTS are largely responsible for work by E cores. DAS typically submits more than 700 activities for scheduling, including those for Time Machine backups, which have changed in Sonoma and later, with implications for LaunchAgents and LaunchDaemons settings.
Have you got any encrypted HFS+ disks you still back up to, or tucked away in storage? Now is the time to plan what to do with them. Here is a guide with practical suggestions.
You realise that a few hours ago you trashed an important file by accident. How can you search your Time Machine backups without looking through them one at a time?
The Eclectic Light Company 