Option A: the tool is accurate, and you've writing 1 TB in 14 hours (73 GB/hr for the entire time the drive has been on).

Option B: The tool is interpreting the SMART data incorrectly, or the drive isn't reporting it correctly.

I mean I don't know which is correct, but it seems odd that in 20 days of ownership, the drive has been awake for only 14 hours, but been writing solidly at the rate of a gig a minute for the whole time.

Option B sounds more likely in my case. I haven't used it much. Mostly just checking some websites. It's not a daily driver.

I've been looking at the Activity Monitor and disk writes for the kernel task are crazy high (hundreds of GBs per hour), especially when Rosetta is involved. The Rosetta daemon seems to use a lot of memory, likely causing excessive swapping. Another suspicious process is... Safari bookmark sync? Can't even image why it needs to write 10GB per hour.

Sounds like 8 GB of RAM is not enough after all...

> "The Rosetta daemon seems to use a lot of memory, likely causing excessive swapping."

I haven't seen this. The rosetta daemon, oahd, is using only 1.3MB on my system (8GB M1 MacBook Air) and I have several large translated apps running. If it's stuck using lots of memory, I guess that's probably a bug.

Its weird that people still have computers that use swap when 16 gigs of ram costs like 80 euros.

Yeah, I hope for the sake of M1 owners that it is Option B, because it means this is likely a flap about nowt.

That said, it does highlight how bad it is that computers now come with the bit that is most likely to wear out being a non-replaceable part.

I double-checked the numbers reported by the driver against doing actual writes to the file system and the numbers reported by the OS, and they match exactly when there is no other activity: writing a 1GB file increases the number by 1GB and a few kilobytes of metadata.

Once the memory is full, it starts swapping a lot and then things go bad.

For the record, here are the numbers from this box: 900GB written in 20 power-on hours, on a 256GB driver.

Critical Warning: 0x00 Temperature: 26 Celsius Available Spare: 100% Available Spare Threshold: 99% Percentage Used: 0% Data Units Read: 15,019,377 [7.68 TB] Data Units Written: 1,759,297 [900 GB] Host Read Commands: 101,021,092 Host Write Commands: 14,010,727 Controller Busy Time: 0 Power Cycles: 75 Power On Hours: 20

My Data Units Written has gone up by 0.3TB in the last hour doing nothing but surfing the web on Safari. I would like to believe that this points to Option B. This is on a 512GB SSD/8GB RAM MBA

That sounds like power management at work. When the drive is not doing anything of course it should turn off.

Option C: OS installation and write amplification

What's the sector size? Maybe it's counting number of sectors *sector size.

> Not sure what to make of the power cycles stat either. It's mostly plugged in at my desk.

I wonder if that's a battery charge cycle metric. Anyone know?

It's how many times the drive is powered on/off.

It's not. My MBP (non M1) has 28,891. The battery would be dead as a doornail. I imagine MacOS just has the ability to put the SSD to sleep when idle.

It does, and it is also configurable in Energy Saver in System Preferences.

Mac can draw more power than a power adapter can supply. In short bursts this is fine.

Some apps (CIv6) will drain the battery completely when plugged in.

No idea if this is related

Are you talking about M1 Macbook Air? Since Apple sell M1 Macbook Air with 30W adapter and I guess it can draw more than 30W, but personally I haven't seen any of it while playing both GPU / CPU intensive games.