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.
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].
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.
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.
>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.
You have not used a file system exceeding 90% use with large files and lots of little files coming and going.
ZFS in particular completely falls off a cliff somewhere between 80% and 90%, due to the copy on write nature of ZFS always allocating and freeing small bits of space. That creates the little gaps all over the FS which murder performance when the big gaps run out.
The old default for this was lower but most modern versions of the ZFS defaults don’t hit this until the vicinity of 96%
It’s not technically the little holes or even CoW that is the problem. It simply switched from a “first fit” to a “best fit” algorithm as it got full which was quite expensive to do the search for.