My laptop has a SSD drive and I run a script which writes every other second to /sys/class/thermal/cooling_device4/cur_state. I don't think this would count as writing to the SSD and thus reducing its remaining number of writing cycles, since procfs and sysfs are virtual filesystems.

Or am I overlooking something and this is an issue?

  • 1
    You are right. Not writing to the SSD doesn't count as writing to the SSD. The same would hold for a RAM drive such as tmpfs.
    – glglgl
    Dec 8, 2018 at 12:29

1 Answer 1


You're entirely correct: virtual filesystems like procfs and sysfs are not stored on disk at all. Their contents are generated on-demand based on kernel data structures in RAM, and writing into them (if possible at all) translates into making changes to in-memory kernel settings.

Writing to procfs or sysfs cannot possibly have any impact to SSD lifetime.

  • But if I'm nit-picking, is that possible writing to /sys control the state of your SSD controller so it will have some impact to the hardware? Dec 8, 2018 at 12:39
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    No, repeated writing to /sys/class/thermal (as the original poster asked) won't have any impact to SSD hardware :-) To have any significant effect, you would have to write into /sys/block/<device name>/ and basically deliberately pick the worst possible settings for a SSD. Even so, modern consumer SSDs have plenty of writing cycles and efficient wear leveling: typically the vendors promise that you could write more than a terabyte every day and the SSD would still have the expected lifetime. Of course, sometimes those promises can be mistaken or less than truthful otherwise...
    – telcoM
    Dec 8, 2018 at 12:53

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