I have a server wity 8 GB RAM

Total 8031464
Used 5146344
Free 2885120

If I execute

# df

it always returns this

tmpfs            4015732         0   4015732   0% /dev/shm

What does it means , I have 4GB unused RAM (0% used all day) ?

And some other doubts related to /dev/shm , please ;

If I see 0% usage all day should I reduce /dev/shm size , for example from 4GB to 1GB ?

If yes, HOW to reduce /dev/shm size ?

May I use this memory location /dev/shm to symlink some folder with heavy IOwait (disk usage) ?



The 'size' of a tmpfs (like /dev/shm) is only the maximum amount of memory it can use. It doesn't actually use that memory unless its storing something, which in this case it isn't.

In short, your /dev/shm isn't actually consuming any memory (well, technically, it's consuming some tiny amount just by existing).

It's difficult to give recommendations without knowing your machine's workload, etc., but there doesn't appear to be any reason to change the defaults.

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