Free Memory Question

[HappyWorld]

[***@main ~]# free -h
             total       used       free     shared    buffers     cached
Mem:          252G        93G       158G       371M       904M        48G
-/+ buffers/cache:        44G       207G
Swap:         8.0G         0B       8.0G

According to stats above, do you think it is safe if i downgrade the memory from 256 GB to 128 GB?

 

[WSWD]

Depends. Was this taken when your site was very busy, or slow, or normal traffic or......? If this is when your site is busy, you're still going to have 30GB for overhead, which should be plenty.

 

[HappyWorld]

@WSWD : it was on normal traffic. But thank you for the opinion. I just installed munin. I will wait for few days and see what it says.

 

[HappyWorld]

I changed my RAM from 256 GB to 128 GB.
Strangely the memory usage dropped too from around 90 GB into 50 GB.
I wonder what caused the drop?
Is it because previously the RAM is used as a kind of cache, and now the cache adjusts itself based on total RAM size?

I also upgraded my PHP from 7.2 into 7.3, but i don't think it caused the +- 40 GB RAM usage drop,
because from some links that i read, PHP 7.3 only improves about 10% from 7.2