When I don’t pack my external data into blend.file the whole scene takes up barelly 20GB of RAM in loading part, but when I pack the external data then the whole scene size becomes 44GB of RAM in loading part (it crashes since I only have 32GB).
Why is that so and is there a possibility to keep the scene at loading part at 20GB of RAM with the external data packed into blend.file?
Packing external files adds to the size of the file? What are you expecting to happen when you increase the size of a file, other than increasing the size of the file? 
Is there a possibility to keep a file size the same after adding to it? Nope. Again, file bigger = bigger file
I was not speaking about the file size, but scene loading size. The scene is getting loaded at 20GB RAM with unpacked textures, but when I pack the textures then it takes up to 44GB of RAM, then the Blender crashes.
That’s the same issue we are discussing here at my last post.
So my question is, why does the RAM usage climb from 20GB to 44GB when i pack the external data?
Because when you open a file it loads into RAM and the file is bigger with packed textures
But the jump in RAM happens only when I am trying to render the scene, so before the scene is rendered it’s loaded on RAM (loading the scene part).
Those 20GB of RAM were in the loading part of the scene, before the render. Now it’s at 44GB of RAM in the loading part of the scene, that’s because I packed the external data. It was not constantly 20GB or 44GB of RAM, but only in the loading part of the scene before the render of the scene.
Difficult to say if you give no more info about the usage of your used external data… 
Could it be that some textures are packed mutliple times… because blender thinks those are different textures now? (Or be marked as save even not used or something??) You may check if you had packed some unused textures also. If not used and refered by file they aren’t loaded. If packed then they are.
All of the external data is used, you can try that by yourself.
You can see that in this screenshot the textures ARE NOT PACKED in the blend.file, and the RAM usage is 377.5 MB (see in the down right corner).
You can see that in this screenshot the texture ARE PACKED in the blend.file, and the RAM usage is 579.0 MB (see in the down right corner)
Those numbers in the down right corner are of a high importance because they are always showing the exact RAM usage blender is using in that exact moment. Sometimes it varies a lot and sometimes not, but packing the external textures almost always doubles it.
Maybe when textures aren’t packed blender can load/unload them on memory only when it’s needed.
But when you pack every textures they need to stay in memory every time.
Yes, that makes sense. So packing external data makes sense only if I want to transfer my blend file to somebody else. Then when somebody else has that blend.file, they just unpack the textures and save them somewhere else on their computer.
yes especially since in your case textures takes such huge amount of memory.
In general it’s much smaller so having pack or unpack doesn’t make a real difference in usability.
It’s also possible to pack and unpack right after that to put all the image in a texture folder next to the .blend, that way you can send both in a zip file .
That is correct, I am putting all of those textures in my folder now. I won’t be packing anything in those blend.files that have huge amounts of texture memory.
