[smartmontools-support] attrlog csv files and SMART 194

[Tim Johnson]

Hello,

I was excited to begin producing historical temperature data for our many hard drives by parsing the attrlog .csv files in /var/lib/smartmontools . In practice, however, I have been hit by the fact that the values for Seagate drives are in the appropriate celsius range, while the values for our HGST drives are 'normalized' at somewhere between 160 and 230.

I am wondering if there is a place I can go to find out how to convert the raw or 'normalized' value stored in the attrlog CSV files into celsius for HGST drives. If it means looking at a specific source file in smartmontools, I can try that. If there is some other shorthand or tool, or option we can add so smartd records the normalized value differently, I think we are open to that too.

Specific examples of what I'm talking about:

In the attrlog for an ST2000DM001-1CH164, SMART 194 is recorded as: 194;44;94489280556;
In the attrlog for an HMS5C4040ALE640, SMART 194 is recorded as: 194;193;176095166495;

Any tips?

Thanks,
Tim

[Christian Franke]

Post by Tim Johnson
Hello,
I was excited to begin producing historical temperature data for our many hard drives by parsing the attrlog .csv files in /var/lib/smartmontools . In practice, however, I have been hit by the fact that the values for Seagate drives are in the appropriate celsius range, while the values for our HGST drives are 'normalized' at somewhere between 160 and 230.
I am wondering if there is a place I can go to find out how to convert the raw or 'normalized' value stored in the attrlog CSV files into celsius for HGST drives. If it means looking at a specific source file in smartmontools, I can try that. If there is some other shorthand or tool, or option we can add so smartd records the normalized value differently, I think we are open to that too.
In the attrlog for an ST2000DM001-1CH164, SMART 194 is recorded as: 194;44;94489280556;
In the attrlog for an HMS5C4040ALE640, SMART 194 is recorded as: 194;193;176095166495;
Any tips?

The normalized value may show 'temperature' or '(some_constant -
temperature)' or something else.
In most cases is is safe to assume that temperature is shown in the
lower byte of the raw value. The upper bytes may encode min/max values.

Try this to get a temperature list from the attrlog file:

sed -n 's,^.*\t194;[^;]*;\([0-9]*\);.*$,\1,p' attrlog.csv | awk '{print
$1 % 256}'

Thanks,
Christian

[Tim Johnson]

Post by Christian Franke
The normalized value may show 'temperature' or '(some_constant -
temperature)' or something else.
In most cases is is safe to assume that temperature is shown in the
lower byte of the raw value. The upper bytes may encode min/max values.
sed -n 's,^.*\t194;[^;]*;\([0-9]*\);.*$,\1,p' attrlog.csv | awk '{print
$1 % 256}'

Brilliant! That does the trick. Thanks!

Tim