[smartmontools-support] nvme 'Data Units Read' and 'Data Units Written' question.

[Robert Fantini]

So I've done some tests and research .
 Wrote a 1GB file, and the data units went up by about 2700.   Although I
do not know how the units are calculated , the writes are not under
reported.

The incredibly high write count  is not unusual for use cases like advanced
scientific testing [ nuclear testing simulations , cloud service providers
etc].

Even though 15.3 PB  have been written ,  the drives have a lot more life
left [ 175+ years at our rate of use] :
https://ark.intel.com/content/www/us/en/ark/products/79620/intel-ssd-dc-p3700-series-2-0tb-1-2-height-pcie-3-0-20nm-mlc.html

                    Endurance Rating  Lifetime Writes      62 PBW (JEDEC
Workload), 17 DWPD

So we'll keep this drive.



On Sat, Jun 29, 2019 at 3:00 PM Robert Fantini <robertfantini at gmail.com>
wrote:

> attached.
>
> On Sat, Jun 29, 2019 at 12:37 PM Christian Franke <
> Christian.Franke at t-online.de> wrote:
>
>> Robert Fantini wrote:
>> > Hello
>> >
>> > We just received a used INTEL 2TB Nvme .    Below is smartctl output.
>> >
>> > These are very high,   could the math be incorrect?
>> > Data Units Read:                    30,035,247,693 [15.3 PB]
>> > Data Units Written:                 11,932,680,343 [6.10 PB]
>>
>>  From NVMe specs (same in 1.0 to 1.4):
>> "Data Units Read: Contains the number of 512 byte data units the host
>> has read from the controller... This value is reported in thousands
>> (i.e., a value of 1 corresponds to 1,000 units of 512 bytes read) ..."
>>
>> Math looks good:
>>
>> $ echo 'scale=1; 30035247693 * 512 * 1000 / (1000^5)' | bc
>> 15.3
>>
>> To check whether smartctl interprets raw data correctly, please provide
>> output of
>>    smartctl -r ioctl,2 -i -A /dev/nvme0
>> as an attachment.
>>
>> Thanks,
>> Christian
>>
>> > PS: thank you for the great tool.
>> PS: You're welcome.
>>
>>
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