[solved] Reduce writing on SD-Card/ move w1 slave files

[Andy_Capone]

Hello everyone
I'm new to Raspberry Pi (own and love one for about a month), Linux and this forum so I hope the is the right section to post my problem.
I know that often writing to the SD-card significantly reduces its lifetime, so I'm trying to put everything to USB or RAM that needs to write lots of stuff. I put the /var directory to a USB-stick and the data from my motion-detection is being written to RAM for example.
Now I'm working on cooling my RasPi and for that reason it detects the CPU- and roomtemperatures every few seconds. The roomtemperature is measured via a ds18b20 which writes to /sys/bus/w1/devices/SENSORID/w1_slave. Now, when I wanted to create a ramdisk for those files, I found out that every directory in /sys/bus/devices seems to be a link:

Code: Select all

andy@raspberrypi /sys/bus/w1/devices $ ls -l
total 0
lrwxrwxrwx 1 root root 0 Aug  4 15:27 28-00000577849d -> ../../../devices/w1_bus_master1/28-00000577849d
lrwxrwxrwx 1 root root 0 Aug  4 15:27 28-00000577f223 -> ../../../devices/w1_bus_master1/28-00000577f223
lrwxrwxrwx 1 root root 0 Aug  4 16:10 w1_bus_master1 -> ../../../devices/w1_bus_master1

What I don't understand is that they seem to point to themselves or am I wrong? If I wanted to mount a ramdisk in /drv/w1 for example, where do I put the links that point there?
Thanks for your advice

[RaTTuS]

/sys
/proc
/dev
are not real filesystems
they don't exist on the SD card [as such]

[Andy_Capone]

Thanks for your reply. Does that mean I don't have to care about how often something is being written there?

[DougieLawson]

Thanks for your reply. Does that mean I don't have to care about how often something is being written there?

The virtual filesystems (/proc /dev /sys) are only in kernel memory. They are never externalised to the SDCard. You can write to them all day (where allowed) and it's just waggling a few ones and zeros in RAM.

[Andy_Capone]

I see, thanks a lot! Problem solved!