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by petecooper 2827 days ago
My computer (macOS Sierra, HFS (Journaled)) has 2x spinning drives of 3TB, and operations are noticeably quicker after an overnight defragmentation run, which I do twice a year or so. Anecdata, granted - but it works for my situation.
2 comments
pfranz 2827 days ago
If it works for you, then great, but here's an article from almost 10 years ago where Apple discourages defragging[1]. There's a bunch of other articles with more specifics showing that advanced defrag features from the 90s were built into the OS years ago[2].

[1] https://support.apple.com/en-us/HT1375 (last updated 2010) [2] http://osxbook.com/software/hfsdebug/fragmentation.html (from 2004)

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petecooper 2827 days ago
I just took a snapshot of one of my hard drives (2TB) from iDefrag:

https://imgur.com/bdGcXXC

The red slivers towards the lower middle are where the reported fragmented files are located, and the lower right is the fragmented files listed by number of fragments descending.

The anonymised .mkv files are training videos with multiple language and subtitle streams. They're exported to a scratch drive and then copied to the the drive they currently reside on.

After a full, offline defrag (including a b-tree rebuild) the legend for defragmentation is a neatly arranged list of that blue/grey colour, no red to be seen.

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sjwright 2827 days ago
Given that macOS automatically defragments sub-20MB files on the fly (which covers 99% of the files which affect perceived system performance) I'd wager money that your experience is 100% placebo.

I know from personal experience how powerful this placebo effect can be.

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petecooper 2827 days ago
>Given that macOS automatically defragments sub-20MB files on the fly (which covers 99% of the files which affect perceived system performance) I'd wager money that your experience is 100% placebo.

Perhaps. I can certainly tell the difference performance when an overnight defrag run has finished, and I have no beef with you to prove or disprove a point.

If you're ever in North Cornwall, UK: drop me a line and I'll show you a before and after over a mug of coffee/tea/etc.

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