Using Flux models reduces the free space on my SSD

[JorgeR81]

When I use Flux models, I notice the free space on the main SSD ( where I have the Portable Comfy UI ) gets smaller, by several GB.
And then it increases again, gradually.

I'm on Windows 10
I only have a GTX 1070 ( 8 GB VRAM )

But I also have 32 GB RAM.
Is using SSD space really necessary ?

Also, the Flux models are stored on a different SSD.
I added extra search paths for some models, to save space on my main SSD.
Is that the reason this happens ?

[JorgeR81]

OK, I see this can happen, if there is not enough VRAM/ RAM: 

"Flux.1-dev on a laptop, RTX 3050 4 GB VRAM, 16 GB RAM"
https://www.reddit.com/r/StableDiffusion/comments/1ek6hsj/flux1dev_on_a_laptop_rtx_3050_4_gb_vram_16_gb_ram/

But, 8 GB VRAM + 32 GB RAM should be enough, right ?

[JorgeR81]

I checked the Task Manager and indeed it reaches 31.7 GB RAM usage, and SSD activity increases at the same time.

I haven't noticed this before, because it only happens when the models are being loaded ( in fp8 or fp16 mode ) or when the prompt is changed ( in fp16 mode ).

Do I need the smaller fp8 models, to prevent going above 32 GB RAM during model loading ?
( I only have the larger fp16 ones )

[ltdrdata]

You can download fp8 version via ComfyUI-Manager

[JorgeR81]

I tried the [dev] Comfy-org model ( 17.2. GB ) with text encoder included.

But RAM usage still goes beyond 32 GB when loading. And SSD usage spikes at the same time.

This is the main SSD, where the portable install is located ( not the one where the Flux models are located ).
So the SSD spike is only generated by the RAM overflow.

[JorgeR81]

Here is the full picture.
This is one also with some of today's updates ( up to c14ac98 )

SSD 0 - has the OS and the Comfy portable install -- you can see usage spikes after all the RAM is used
SSD 1 - has the Flux models ( via extra search path ) -- usage goes down after the model is loaded
SSD 2 - external SSD ( not related ) -- no activity

After generation VRAM usage goes down from 7.2 GB to 1 GB,
and RAM usage increases somewhat proportionally ( same as for the fp16 versions ).

On a side note.
Why so much CPU usage, while generating, if GPU usage is still low ?
This is an intel i7-7700 ( 4 cores, 8 threads )
The same happens with less taxing models ( e.g. SD1.5 and 512 x 512 ), where CPU usage will be about 45% and GPU usage is about 3 %

---

[RandomGitUser321]

The drive usage is due to it using the page file. The space reduction is due to Window's page file being set to "system managed size." Basically, you're out of ram and when the default page file size fills up, it expands it to a larger size and this is usually permanent until you change the setting within the system properties.

[JorgeR81]

OK, thanks !
I'm leaving this setting as is, for now, because I probably need it to run Flux, since the fp8 models also require more than 32 GB RAM
I'm marking this as answered, because I've already opened an issue about the Flux RAM usage: #4239