[supermatt]

  SMART/Health Information (NVMe Log 0x02)
  Critical Warning:                   0x00
  Temperature:                        32 Celsius
  Available Spare:                    100%
  Available Spare Threshold:          99%
  Percentage Used:                    1%
  Data Units Read:                    42,513,003 [21.7 TB]
  Data Units Written:                 35,670,814 [18.2 TB]
  Host Read Commands:                 444,309,142
  Host Write Commands:                237,126,099
  Controller Busy Time:               0
  Power Cycles:                       213
  Power On Hours:                     199
  Unsafe Shutdowns:                   13
  Media and Data Integrity Errors:    0
  Error Information Log Entries:      0

[marcan_42]

The SMART info does not include the drive size, which was an omission in my request for info tweet which I regret :)

So 18TB / 256GB = 70 drive writes is 1%.

For the 2T drive, we had 150TB = ~50 drive writes being 3%.

So, it seems this isn't linear after all. But it's also not constant; 150TB would put you at 8% used on your 256GB model with this scaling (instead of the ~23% if it were linear), which is still not insignificant, and would still get you to 100% within a couple years. Though there is significant rounding error with the "1%" figure.

I saw someone else mention 3% on Twitter too and asked for their drive size, so I hope that can give me another more accurate data point.

[supermatt]

I just assumed that this was some deep "app nap", where its effectively swapping the entire state of an inactive app to disk. That would likely explain why the usage is scaling with available RAM, rather than storage space.

I get that its a much higher wear than we would traditionally expect, but given I have 8GB of RAM that seems near inexhaustible., maybe it just a different approach to memory management, permitted by the blazingly fast storage we now have access to? I simply couldn't run all this stuff on my 16GB 2015 machine.

I cant run figma though - that thing eats 4GB for a smallish project, so it almost always complains about my available memory when im using figma.

[marcan_42]

So, going back over the numbers and with a 256GB 3% user confirmed on Twitter, it seems like the ratings are:

2TB model: 5000TBW

256GB model: 2000TBW

That means that, at the worst known rate that David had (150TB in 2 months), a 256GB drive would reach lifetime writes in ~2 years. That's still way too fast, so this is still something Apple needs to adjust if it is happening to people (and given what he told me about the write rates he was seeing while using and switching apps, it really does seem like a bug, not normal app swapping).

FWIW, the "app nap" thing is what iOS does, but macOS can't do that because Mac apps aren't really designed that way. macOS just does traditional swap plus compression, as far as I know.

[supermatt]

App Nap is definitely a MacOS thing - but it hasn't traditionally behaved in this way.

I'm aware it will be a form of virtual memory management - but given im currently (and actively) running safari, chrome, firefox, affinity designer, affinity photo, slack, mail, a handful of terminals, a couple of ios apps, an iphone 11 simulator, 2 android emulators, 4 instances of vscode recompiling code as I type, and a bunch of utility apps theres definitely more than just a traditional swap going on here. Its an 8GB machine, and it really feels like it has unlimited RAM (until i open figma, as mentioned before - theres something about that app that the m1 really doesnt like).

Of course, if it is a bug, ill be happy to have it fixed :)

Also, I just realised you are the OP :) And the guy working on asahi (awesome!). Would love to know more if you get to the bottom of this behaviour - intentional or otherwise!

[rasz]

Those ratings are unrealistic, suggest 8000 write cycle flash for the small drive.