M1 Mac owners are experiencing high SSD writes over short periods of time

Re:M1 Mac owners are experiencing high SSD writes over short... by ryan29 on Wednesday February 24, 2021 @01:43AM (#26247295)

How do you only have 558 PoH with ~900 days of daily use? Do you only use it for 30m per day?

Here's a 512GB WD Black from my home lab server. It runs ~10 super light usage VMs with Docker stacks that include 2 GitLab instances, 2 GitLab runners, 3 Nextcloud instances, 3 Redmine instances, 1 Gitea instance, 2 Drone runners, 1 Minio instance, 1 Nexus instance, 1 Emby instance (w/transcoding), and various reverse proxies, etc..

The write endurance is supposed to be 300TBW, so it should really be over 20% used but says 0%.

    SMART/Health Information (NVMe Log 0x02)
    Critical Warning:                   0x00
    Temperature:                        38 Celsius
    Available Spare:                    100%
    Available Spare Threshold:          10%
    Percentage Used:                    0%
    Data Units Read:                    95,066,245 [48.6 TB]
    Data Units Written:                 135,910,315 [69.5 TB]
    Host Read Commands:                 972,466,473
    Host Write Commands:                2,504,003,547
    Power On Hours:                     17,383

    Error Information (NVMe Log 0x01, max 256 entries)
    No Errors Logged

Compare it to a 500MB Crucial MX500 under the same load which is supposed to have 180TBW:

    Model Family:     Crucial/Micron BX/MX1/2/3/500, M5/600, 1100 SSDs
    Device Model:     CT500MX500SSD1
    Serial Number:    
    Sector Sizes:     512 bytes logical, 4096 bytes physical
    Rotation Rate:    Solid State Device
    Form Factor:      2.5 inches

    ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
    9   Power_On_Hours          0x0032   100   100   000    Old_age   Always       -       11225
    173 Ave_Block-Erase_Count   0x0032   032   032   000    Old_age   Always       -       1032
    194 Temperature_Celsius     0x0022   067   044   000    Old_age   Always       -       33 (Min/Max 0/56)
    202 Percent_Lifetime_Remain 0x0030   032   032   001    Old_age   Offline      -       68
    246 Total_Host_Sector_Write 0x0032   100   100   000    Old_age   Always       -       59166051308

That's 68% used after ~30TBW (59,166,051,308 sectors*512 = 30,293,018,269,696 bytes).

What I've learned from trying to diagnose those MX500s is that TBW doesn't really matter all that much. It's the P/E cycles that really count. For example, the MX500s are rated for 1500 erase cycles (#173 above) IIRC.

I've also become skeptical of many SMART implementations. I know the PoH on the Crucials is incorrect because when they were new they were reporting 45 days of PoH on a system with 76 days of uptime. So if the manufacturers can't get something as simple as PoH right, how can anything be trusted?

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Re:M1 Mac owners are experiencing high SSD writes over short... by read_if_gay_ on Wednesday February 24, 2021 @06:16AM (#26248795)

I have a 1TB MX500 and a much older 240GB M500 and the PoH stats are similarly unrealistic for both. The MX500 has ran close to 24/7 for two months now and reports 328h which is like 14 days. The M500 reports 12k hours (~1.35 years) but it's 5+ years old and I'm sure it should be higher.

OTOH the number of power cycles they report seem to be too high, at 45 and 2332 respectively. Maybe that's related?

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Re:M1 Mac owners are experiencing high SSD writes over short... by blinkingled on Wednesday February 24, 2021 @08:06AM (#26249417)

I have a different work laptop so I mostly use this on weekends and weeknights and I believe NVME APST mode may be affecting it.

Then there's always the possibility of wrong interpretation of the numbers as every OEM has possibly different implementation.

In Apple's case it's more likely they have the right implementation as they make both the software and the hardware. There could still be bugs..

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