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Apple Core Rot: File System Performance Problems, Thunderbolt 3 Performance Problems, Thunderbolt 3 Disconnect Problems, etc.

Apple software usablity is plummeting in every area, with Apple Core Rot now hitting a key layer of the operating system, the file system layer.

Sebastian B writes:

A question about diglloydTools IntegrityChecker. I recently switched from a 2012 to a 2017 MacBook Pro (and thus from macOS 10.9 to 10.13). I promptly noticed that, on basically the same data set, the 2017 machine is much slower at enumerating files when ic update is run (on the internal SSD, /Users folder).


Any idea what could be causing the slow reads? Perhaps an APFS bug? Bad code in 10.13? I'd have expected the 2017 SSD to be at least no slower than the 2012 one (or an HDD, for that matter). It's not a big problem, but I also wouldn't be too unhappy if there were something I could do about it.

MPG: this performance issue arose somewhere around macOS 10.13.3, around the time of the Spectre and Meltdown fixes (or ealier, Apple inserted changes before the public announcements of those issues). The file system performance issues might or might not be related and in only some cases.

Worst of all are indeed major speed losses in enumerating files. I have seen losses as high as 10X, with the result that the Java version of IntegrityChecker usually runs faster than the native version! But this issues are not confined to IntegrityChecker; they are general and severe and surely due to yet more Apple quality control failures.

There could be as many as three issues involved, which affect APFS and macOS Extended both:

  • Major speed losses in enumerating files (up to 10X slower).
  • A serious bug that causes up up to a 3X variation in speed on the same test on the same drive within minutes. I saw this repeatedly on the iMac Pro when testing back in January of this year. I saw it on both Thunderbolt 3 and on internal SSDs.
  • POSIX APIs, carbon APIs, Java APIs, even Finder copy all show severe performance hits at times, making it impossible to optimize speed.

APFS has its own serious performance problems of its own that macOS Extended does not have (I do not run APFS, not even for my boot drive because APFS has such erratic performance; see Upgrading to macOS High Sierra Without the Forcible “Upgrade” to APFS).

Apple has made a serious hash out of Disk Utilty also and in general besides committing cardinal sins of exposing user passwords has shipped garbage software to users last fall. Is it any surprise that file system performance might also be debased?

Since last autumn when I tested them, I have seen losses as large as 1000 MB/sec (down from 2700 MB/sec to 1700 MB/sec) for large transfers on two Thunderbolt 3 drives (LaCie Bolt 2TB SSD, TekQ Rapid 500GB SSD. The losses range from 33% to 45%, depending on whether it is reads or writes. I do not yet know if this is a Thunderbolt 3 thing only, but very recently I’ve seen the new 1TB OWC Envoy Pro EX (also Thunderbolt 3) perform at just 55% of rated speed. And that's with multiple programs, not just DiskTester: DiskTester, BlackMagic, Finder (unbelievably slow), . And that’s on both APFS and macOS Extended.

Then there are the Thunderbolt 3 disconnect problems, which might even be a hardware bug that neither Apple nor Intel will publicly acknowledge. It’s a dirty secret business and shameful at that.

There might also be Thunderbolt 3 cabling issues that reduce performance for cables over 0.5 meter, so if you are not getting the performance you expect, play with cabling and keep it short and use only the best quality Thunderbolt 3 cables capable of 40 Gb/sec.

I don’t currently have the hardware or time to ferret out all the issues; the causes are not obvious other than I am all but certain they all arose within the past 6 months, as Apple greatly damaged performance system-wide.

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