(Resolved) VM Memory vs OS recommended settings

[loukingjr]

I guess I'm missing something. I was under the impression when you set up a guest the memory settings should be based on the same requirements as it would be for the OS on hardware. Is this not the case?

I'm also somewhat confused about VRAM apparently. My screen is 2540x1440x32 which works out to be appx. 14.6MB. That doesn't include compositing. I'm not sure how that factors in but most OS's seem to have 256 levels of transparency. Does this affect the amount of VRAM that should be set or not?

edit: for example, the system requirements (I assume the minimum) for Windows 7 64bit are 2048MB RAM and 128MB VRAM (for Aero). The defaults set by VirtualBox are 512MB RAM and 48MB VRAM.

[mpack]

I guess I'm missing something. I was under the impression when you set up a guest the memory settings should be based on the same requirements as it would be for the OS on hardware. Is this not the case?

There are minimum requirements and there are recommendations. Which are you referring to? (a link would be good). In general yes, all other things being equal you would follow the recommendation. However if you were referring to the VRAM question from the other thread earlier today, the MS advice is no doubt considering the current graphics card market, it isn't thinking VM where all the rendering actually takes place on another PC (the host).

I'm also somewhat confused about VRAM apparently. My screen is 2540x1440x32 which works out to be appx. 14.6MB. That doesn't include compositing. I'm not sure how that factors in but most OS's seem to have 256 levels of transparency. Does this affect the amount of VRAM that should be set or not?

That is quite a high end resolution for a VM I would think, VRAM requirements would be quite high. Transparency per se doesn't increase the memory requirement at all - 32bits of color includes 3 x 8bit color channels plus 1 byte of transparency (256 levels) per pixel. However there would presumably be other images to combine, and they require memory as well - perhaps in VRAM, perhaps not. And they wouldn't all be fullscreen.

[loukingjr]

thanks mpack. I suppose I'm more interested in recommendations than the minimum system requirements. the only problem with finding links is, as I'm sure you're aware, for the same OS they can vary widely. Microsoft on their pages gives system requirements. I have read elsewhere that those are minimums. On Ubuntu's own pages they have stated that Ubuntu 12.04 can be installed in a machine with as little as 20MB RAM. I can't see how one could run Unity 3D in 20 MB which I'm fairly certain you can't. But they also have minimum requirements of 512MB RAM for the 64bit version and I have seen recommendations for RAM as high as 2048MB and VRAM of 128MB.

I guess the point is the practice in the past was an OS developer would publish the absolute minimums to get their OS to work at all and still seems to be true. Normally I just go with what the recommended settings are and maybe a smidge more.

That is quite a high end resolution for a VM I would think, VRAM requirements would be quite high.

in the case of my Windows 7 guest, I have the VRAM set to 256MB because when I had it set at 128MB, it would occasionally abort even running in a 1920x1080 window. Now it doesn't. It still will occasionally abort in fullscreen however even set to 256MB.

thanks again. I have plenty of RAM to play with so I'll just continue to use, for a guest when I can find them, people's recommendations for the particular OS to run well on hardware.