• macOS – Time Machine Exclude Directory

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    I am a newb to Macs and macOS. I am currently running Mojave on a MacBook Air 2017 that I bought a year ago. I am no way near a power user so I need a little help.

    I have been making Time Machine backups since August. It just came to me that I can exclude some files from Time Machine backup. Is it possible to exclude a directory? Specifically I am looking at excluding FF cache since the files change frequently. Is this a good idea?

    In Firefox, I did about:cache to find the location of FF cache. This is what I found:


    I assume I can just open Time Machine preferences and use the above directory to exclude?

    While I am at it….I currently make Time Machine backups once a week to an external drive. I just do a manual backup. Is this okay since I don’t have my external drive connected all the time?

    Viewing 3 reply threads
    • #2319034
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      • #2319105

        Thanks for the article Alex. I will exclude the FF cache.

        I guess I shouldn’t really worry about disk space. My macOS SSD is only 128GB and my backup Seagate drive is 2TB.

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    • #2319047

      @bassmanzam – I do what you do regarding manual backups. I don’t have my external drive connected all the time, only when I make a manual backup, which is about once a month or before a security update. Works for me.

      However, I did read something somewhere once that even while not actively doing a backup Time Machine is doing something in the background. I wondered if making more frequent backups would lessen the amount of this activity and hence perhaps speed up the computer. But I’ve never looked into it.

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      • #2319061

        bassmazam: About NOT saving folders in Time Machine and (as recommended by Alex when I was still writing this — he is that quick):


        For more detail, looking into my Mac one can find this:


        Otherwise: I do more or less what you and DrBonzo do and only do TM back ups maybe once a month. One thing I understand that TM does in background is to save snapshots on the Mac’s hard drive until the space preallocated for this is full. Those snapshots so saved are used, I suppose, to speed up back ups when one finally gets around to plugging in the external TM hard disk.

        Ex-Windows user (Win. 98, XP, 7); since mid-2017 using also macOS. Presently on Monterey 12.15 & sometimes running also Linux (Mint).

        MacBook Pro circa mid-2015, 15" display, with 16GB 1600 GHz DDR3 RAM, 1 TB SSD, a Haswell architecture Intel CPU with 4 Cores and 8 Threads model i7-4870HQ @ 2.50GHz.
        Intel Iris Pro GPU with Built-in Bus, VRAM 1.5 GB, Display 2880 x 1800 Retina, 24-Bit color.
        macOS Monterey; browsers: Waterfox "Current", Vivaldi and (now and then) Chrome; security apps. Intego AV

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    • #2319121

      I backup hourly to Time Machine (the way it was designed). If your drive is unplugged, it will make local snapshots to your internal hard drive until you plug the external drive back in (performance-wise it doesn’t really impact your Macs performance).

      The article is correct on excluding folders. I exclude stuff that frequently changes as well just to make my Time Machine backups faster.

      Nathan Parker

      2 users thanked author for this post.
    • #2319122

      Forgot to mention I have a macOS Switcher Guide for Windows Users on here. It’s free and should help you feel right at home using a Mac.

      Nathan Parker

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