Mac – Time Machine and work directory

backupfilesystemtime-machine

During my daily work, I tend to receive large files (up to a few hundred GB) which are only used for a few hours and then deleted.

I am not sure how Time Machine works, but I suppose that every file written on my drive will become a part of my backup history and that this could have an impact on TimeMachines operations and performance.

Would it be helpful, in this use case, to have a work directory that is excluded from TimeMachine's backup sources? What, on the other hand, would be the impact of allowing all those large files to become a part of the backup?

Best Answer

As you say with each little change in a file will mean it will be backed up again by Time Machine. Often this makes hardly any sense and will bloat the Time Machine backup drive unnecessarily.

I recommend excluding folders that contain large files and change often from Time Machine backups. To do so, go to System Preferences > Time Machine > Options > +. My exclusion list includes the following paths:

  • Download folder /Users/[me]/Downloads
  • My virtual machines (Parallels Windows, etc.) /Users/[me]/VMs
  • Caches, such as Spotify /Users/[me]/Library/Application Support/Spotify/PersistentCache
  • Dropbox folders /Users/[me]/Dropbox

Naturally you should decide for yourself what is meaningful to exclude on your machine and have another backup strategy for those files.

Alternatively, or on top of that you can use the free utility TimeMachineEditor to lower the time interval of backups (default is one hour). From the webpage:

TimeMachineEditor is a software for macOS that lets you change the default one-hour backup interval of Time Machine. You can change the interval or create other types of scheduling (see the screenshots below).

This is useful if you don’t need to backup every hour and don’t want the performance penalty. For example you might be frequently creating or modifying files which would cause long-running backup operations throughout the day. enter image description here

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