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Comment by SXX | Hacker News Reader

So it's looks bad on my Macbook Air M1 16GB:

  Percentage Used:                    3%
  Data Units Read:                    47,004,809 [24.0 TB]
  Data Units Written:                 47,469,528 [24.3 TB]
  Host Read Commands:                 153,293,725
  Host Write Commands:                218,787,006

It's been in-use for two months only and I haven't even compiled anythig on it and all my usage was: light gaming in few 2D games, Firefox and some films.

UPD: it's 256GB SSD model.

View on HN

You're where I am and I've had this Intel MBP for nearly 4 years and haven't been nice to it (compiling, etc).

    Percentage Used:                    3%
    Data Units Read:                    57,377,073 [29.3 TB]
    Data Units Written:                 77,652,525 [39.7 TB]
    Host Read Commands:                 1,297,472,434
    Host Write Commands:                1,855,797,459

I have 10x your host r/w commands. I wonder if the size of the SSD's blocks on these new MBP are very large so you get large physical writes for small OS writes? Or maybe the controller is bad at coalescing writes?

~10x off could also just be bad math in the smartdata path somewhere, either on the drive, or in the OS.

Intel MBP at two years

```

=== START OF SMART DATA SECTION === SMART overall-health self-assessment test result: PASSED

SMART/Health Information (NVMe Log 0x02) Critical Warning: 0x00 Temperature: 42 Celsius Available Spare: 100% Available Spare Threshold: 99% Percentage Used: 23% Data Units Read: 439,149,863 [224 TB] Data Units Written: 407,143,345 [208 TB] Host Read Commands: 2,930,228,690 Host Write Commands: 1,777,317,283 Controller Busy Time: 0 Power Cycles: 103 Power On Hours: 1,691 Unsafe Shutdowns: 49 Media and Data Integrity Errors: 0 Error Information Log Entries: 0 ```

Ouch.

My M1 Mac Mini is also at 3% after 2 months, 1 TB disk:

  Percentage Used:                    3%
  Data Units Read:                    168,154,606 [86.0 TB]
  Data Units Written:                 169,999,872 [87.0 TB]
  Host Read Commands:                 1,077,848,202
  Host Write Commands:                743,848,335

this is a secondary dev machine, so while it's been on and idle for almost 500 hours, it's only had a week or two of "active work".

All of these values are higher than my workhorse 2017 MBP that I’ve used nearly everyday since I got it.

Could something be wrong with smartctl?

Mine is about 20 days old. MacBook Air M1 16Gb 1TB Drive:

    Percentage Used:                    0%
    Data Units Read:                    2,219,368 [1.13 TB]
    Data Units Written:                 2,141,099 [1.09 TB]
    Host Read Commands:                 28,719,296
    Host Write Commands:                26,061,193
    Controller Busy Time:               0
    Power Cycles:                       179
    Power On Hours:                     14

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

> 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 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.

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

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.

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

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...

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

> "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.

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

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

Option C: OS installation and write amplification

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.

Adding my data points: Macbook Air M1 16GB RAM, 512GB SSD. I have had the laptop for 4 days, and so far only used it for OS updates, a little Discord usage, web browsing (Firefox) and a small amount of programming (no Spotify).

   Percentage Used:                    0%
   Data Units Read:                    596,588 [305 GB]
   Data Units Written:                 404,196 [206 GB]
   Host Read Commands:                 8,532,827
   Host Write Commands:                3,851,891

Which Terminal command can I use to get this data? (I don't have an M1 MacBook, I'm just curious.)

[edit] Here's my data:

  Percentage Used: 2%
  Data Units Read: 51,571,905 [26,4 TB]
  Data Units Written: 32,365,209 [16,5 TB]
  Host Read Commands: 1,291,777,925
  Host Write Commands: 720,050,493

I got my MacBook (15", 16 GB RAM, 512 GB SSD) in July 2018.

    brew install smartmontools && sudo smartctl --all /dev/disk0

Thanks!

That only works if you already have be Brew installed :) you can get it at https://brew.sh

or with MacPorts:

> sudo port install smartmontools && sudo smartctl --all /dev/disk0

Web browsers typically cache tons of data on disk. I wonder if the people with higher usage are all running something other than Safari?

What should possibly make Firefox use disk more heavily on M1 Mac than it does on Linux? I've been using Firefox for decade and it never caused 0.5TBW / day on my Samsung SSDs.

Could be different OS behavior in terms of syncing to disk?

I've had mine between two and three months. My writes are significantly lower than yours.\n

SMART/Health Information (NVMe Log 0x02) Critical Warning: 0x00 Temperature: 27 Celsius Available Spare: 100% Available Spare Threshold: 99% Percentage Used: 0% Data Units Read: 8,424,532 [4.31 TB] Data Units Written: 5,496,149 [2.81 TB] Host Read Commands: 122,463,637 Host Write Commands: 59,624,967 Controller Busy Time: 0 Power Cycles: 200 Power On Hours: 60 Unsafe Shutdowns: 6 Media and Data Integrity Errors: 0 Error Information Log Entries: 0

I mostly stick to Apple applications because they seem to get much better performance, i.e. Safari instead of Firefox. Other applications that I use are Emacs, discord, mail, calendar.

Data point:

  SMART/Health Information (NVMe Log 0x02)
  Critical Warning:                   0x00
  Temperature:                        26 Celsius
  Available Spare:                    100%
  Available Spare Threshold:          99%
  Percentage Used:                    0%
  Data Units Read:                    21,290,808 [10.9 TB]
  Data Units Written:                 17,018,375 [8.71 TB]
  Host Read Commands:                 128,112,411
  Host Write Commands:                89,074,700
  Controller Busy Time:               0
  Power Cycles:                       174
  Power On Hours:                     80
  Unsafe Shutdowns:                   6
  Media and Data Integrity Errors:    0
  Error Information Log Entries:      0

8GB/256GB three months old. Mostly used to write code using VS Code and browsing with Chrome. I've also compiled a lot of Haskell code.

Strange coincidence... I have identical power cycles to you.

Also

Read 1 entries from Error Information Log failed: GetLogPage failed: system=0x38, sub=0x0, code=745

16GB/1TB model, two months old:

  SMART/Health Information (NVMe Log 0x02)
  Critical Warning:                   0x00
  Temperature:                        24 Celsius
  Available Spare:                    100%
  Available Spare Threshold:          99%
  Percentage Used:                    0%
  Data Units Read:                    3,019,145 [1.54 TB]
  Data Units Written:                 3,392,635 [1.73 TB]
  Host Read Commands:                 55,076,557
  Host Write Commands:                29,421,973
  Controller Busy Time:               0
  Power Cycles:                       100
  Power On Hours:                     28
  Unsafe Shutdowns:                   16
  Media and Data Integrity Errors:    0
  Error Information Log Entries:      0

Doesn't seem too bad.

16GB/1TB about a month old:

  SMART/Health Information (NVMe Log 0x02)
  Critical Warning:                   0x00
  Temperature:                        32 Celsius
  Available Spare:                    100%
  Available Spare Threshold:          99%
  Percentage Used:                    0%
  Data Units Read:                    16,603,470 [8.50 TB]
  Data Units Written:                 15,747,066 [8.06 TB]
  Host Read Commands:                 95,905,593
  Host Write Commands:                62,087,286
  Controller Busy Time:               0
  Power Cycles:                       93
  Power On Hours:                     52
  Unsafe Shutdowns:                   7
  Media and Data Integrity Errors:    0
  Error Information Log Entries:      0

FWIW I've installed each incremental MacOS update the day it came out.

That's double the reads/writes of my 16 GB/1 TB 2020 Intel MBP for less than 1/3 the Power On Hours. Ratio between data total and read and write commands is quite different though.

    SMART/Health Information (NVMe Log 0x02)  
    Critical Warning:                   0x00  
    Temperature:                        32 Celsius  
    Available Spare:                    100%  
    Available Spare Threshold:          99%  
    Percentage Used:                    0% 
    Data Units Read:                    8,413,842 [4.30 TB]
    Data Units Written:                 8,138,306 [4.16 TB]
    Host Read Commands:                 187,292,832
    Host Write Commands:                154,212,201
    Controller Busy Time:               0
    Power Cycles:                       105
    Power On Hours:                     171

16GB/1TB, also two months old:

  SMART/Health Information (NVMe Log 0x02)
  Critical Warning:                   0x00
  Temperature:                        34 Celsius
  Available Spare:                    100%
  Available Spare Threshold:          99%
  Percentage Used:                    2%
  Data Units Read:                    117,513,026 [60.1 TB]
  Data Units Written:                 110,686,292 [56.6 TB]
  Host Read Commands:                 506,322,545
  Host Write Commands:                351,505,939
  Controller Busy Time:               0
  Power Cycles:                       389
  Power On Hours:                     388
  Unsafe Shutdowns:                   40
  Media and Data Integrity Errors:    0
  Error Information Log Entries:      0

M1 8gb Macbook Air here:

Percentage Used: 0%

Data Units Read: 28,383,716 [14.5 TB]

Data Units Written: 26,487,969 [13.5 TB]

Host Read Commands: 137,200,722

Host Write Commands: 155,386,158

VSCode, compiling, generally programming work load, with heavy multi tasking. I would say ~1 month old.

My 2016 MBP, 500GB SSD with a ton of nodejs development (so lots of disk i/o):

    Percentage Used:                    5%
    Data Units Read:                    198,797,763 [101 TB]
    Data Units Written:                 151,801,865 [77.7 TB]
    Host Read Commands:                 4,494,028,451
    Host Write Commands:                1,965,182,650

A new system should not have done that much work already in that short a time.

m1 mac mini 256 GiB drive, 16 GiB memory. Usage is as a thin client to beefier (louder, and hotter) machine in another room; youtube; slack; zoom; discord. Used since 22 Jan 2021.

data point

  Percentage Used:                    0%
  Data Units Read:                    1,815,191 [929 GB]
  Data Units Written:                 1,854,253 [949 GB]
  Host Read Commands:                 31,584,364
  Host Write Commands:                25,360,962

data point verbose

  SMART/Health Information (NVMe Log 0x02)
  Critical Warning:                   0x00
  Temperature:                        31 Celsius
  Available Spare:                    100%
  Available Spare Threshold:          99%
  Percentage Used:                    0%
  Data Units Read:                    1,815,191 [929 GB]
  Data Units Written:                 1,854,253 [949 GB]
  Host Read Commands:                 31,584,364
  Host Write Commands:                25,360,962
  Controller Busy Time:               0
  Power Cycles:                       102
  Power On Hours:                     33
  Unsafe Shutdowns:                   7
  Media and Data Integrity Errors:    0
  Error Information Log Entries:      0

Wow, I just checked on my windows laptop with heavy use 19 TB lifetime writes in a year.

data point:

    Percentage Used:                    0%
    Data Units Read:                    7,920,747 [4.05 TB]
    Data Units Written:                 1,490,848 [763 GB]
    Host Read Commands:                 90,988,727
    Host Write Commands:                34,766,350

Usage: 3 months~ wrote an ts web app in development over about 6-8 weeks and then 4 weeks of regular gaming (Steam:EU4). Development was all in terminal (vim + npm).

Model: Air 7C16GB/256GB

I have an Intel MBP 16 with twice as many read/write bytes but still shows 0% used. Not sure how they are calculating the percent.

How big of a drive is it? So far, most of the 3%+ used ones have 2TB drives, which is the opposite of what you would naively expect.

On my older (3+ year now) MPB 16 with a 512GB drive I get:

    SMART/Health Information (NVMe Log 0x02)
    Critical Warning:                   0x00
    Temperature:                        41 Celsius
    Available Spare:                    100%
    Available Spare Threshold:          10%
    Percentage Used:                    22%
    Data Units Read:                    621,054,721 [317 TB]
    Data Units Written:                 483,003,547 [247 TB]
    Host Read Commands:                 9,028,855,382
    Host Write Commands:                3,924,827,022
    Controller Busy Time:               16,789
    Power Cycles:                       8,373
    Power On Hours:                     6,828
    Unsafe Shutdowns:                   375
    Media and Data Integrity Errors:    0
    Error Information Log Entries:      271

Wow. How long ago did you get the MBP 16"? I've been running this system as my daily driver for >12 months and see very different numbers from you:

  smartctl 7.2 2020-12-30 r5155 [Darwin 20.4.0 x86_64] (local build)
  Copyright (C) 2002-20, Bruce Allen, Christian Franke, www.smartmontools.org

  === START OF INFORMATION SECTION ===
  Model Number:                       APPLE SSD AP8192N
  Serial Number:                      XXXXXXXXXXXXX
  Firmware Version:                   1161.100
  PCI Vendor/Subsystem ID:            0x106b
  IEEE OUI Identifier:                0x000000
  Controller ID:                      0
  NVMe Version:                       <1.2
  Number of Namespaces:               1
  Local Time is:                      Tue Feb 23 17:01:28 2021 PST
  Firmware Updates (0x02):            1 Slot
  Optional Admin Commands (0x0004):   Frmw_DL
  Optional NVM Commands (0x0004):     DS_Mngmt
  Maximum Data Transfer Size:         256 Pages

  Supported Power States
  St Op     Max   Active     Idle   RL RT WL WT  Ent_Lat  Ex_Lat
   0 +     0.00W       -        -    0  0  0  0        0       0

  === START OF SMART DATA SECTION ===
  SMART overall-health self-assessment test result: PASSED

  SMART/Health Information (NVMe Log 0x02)
  Critical Warning:                   0x00
  Temperature:                        37 Celsius
  Available Spare:                    100%
  Available Spare Threshold:          99%
  Percentage Used:                    0%
  Data Units Read:                    53,827,033 [27.5 TB]
  Data Units Written:                 37,342,497 [19.1 TB]
  Host Read Commands:                 704,072,000
  Host Write Commands:                669,901,451
  Controller Busy Time:               0
  Power Cycles:                       234
  Power On Hours:                     528
  Unsafe Shutdowns:                   74
  Media and Data Integrity Errors:    0
  Error Information Log Entries:      0

I think he means 16GB, not 16" as he mentions 3 yr old but 16" didn't exist 3 years ago.

Yeah, should have been more specific - it's a MacBook Pro (15-inch, 2017)

older doesn't mean anything relevant to anyone but you. Did it have its bar mitzvah or is it 3 years old, nobody knows but you.

My 2016 MBP shows very similar numbers, though my % is even higher (26%):

  SMART/Health Information (NVMe Log 0x02)
  Critical Warning:                   0x00
  Temperature:                        30 Celsius
  Available Spare:                    88%
  Available Spare Threshold:          2%
  Percentage Used:                    24%
  Data Units Read:                    356,923,637 [182 TB]
  Data Units Written:                 354,603,847 [181 TB]
  Host Read Commands:                 2,817,724,668
  Host Write Commands:                2,270,199,931
  Controller Busy Time:               0
  Power Cycles:                       21,443
  Power On Hours:                     996
  Unsafe Shutdowns:                   21
  Media and Data Integrity Errors:    0
  Error Information Log Entries:      0

Pardon me. I have 256GB model. While I used it daily for almost 2 months now it's still sounds crazy to have 25TBW for my usage. I didn't used it for any programming or compilation, no brew package builds either. All I did is used Firefox, downloaded like 30GB of torrents and then watched some Netflix. Also I haven't even moved any of my files to this laptop: so no photo archive, no email sync or dropbox, literaly no usage.

All I can hope for is that it's some kind of bug in SMART or might be Apple gonna fix it soon. Since I use my Kubuntu desktop with Samsung 850 PRO 256GB way more heavily and I barely got to 30TBW in like 4 years.

Yea i'd personally be pretty annoyed if my macbook was just writing that much data in the background slowly wearing out my ssd, 25tb over 2 months is just silly.

checked my 2015 15" that i've been using non stop for over 3 years and it's at 96tb which is 2.6 a month.

You can also keep an eye on the data counter in activity monitor while it's on. At that kind of numbers you're doing to catch it even if it's periodic: it's got a running total too since the Mac was switched on.

Torrents suck for SSD lifetime, the chunk size is typically 16kb but chunks aren’t downloaded whole and in order, so you might end up with a lot of wear and tear unless the file system and the torrent client/library are both working together to eliminate the partial writes.

However, it doesn’t seem that torrents are a common factor in user accounts, and 30GiB in torrents would not account for that much write amplification, so carry on!

How about Time Machine backups? I suspect this is part of it. I believe that Time Machine does keep local snapshots.

Apple better come to my house and fix it here or just bring me a new laptop. I'll take a normal intel at this rate. I don't have the time for them to monkey around with it.

SMART/Health Information (NVMe Log 0x02)

Critical Warning: 0x00

Temperature: 29 Celsius

Available Spare: 100%

Available Spare Threshold: 99%

Percentage Used: 2%

Data Units Read: 18,188,656 [9.31 TB]

Data Units Written: 23,776,092 [12.1 TB]

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