virtualbox.org

I found one related post and nothing specific in the documentation about this.

I am wondering about memory and processor limitations, as pertains to running two simultaneous guests.
I have an AMD 64x2 Athlon 6000+ with 8GB DDR2 mem and host Ubuntu 11.10 GUI is my primary workstation.
I think my first confusion stems from not understanding just how much of my physical resources I need to allot to a given vm.

For instance, because I fear that I am not able to give up Windows cold-turkey, I have a vm that I set up to replace one of my Windows boxes. It runs Win 7 Professional 64 bit with MS Office Home & Student 2010. When I built it, I gave it a 50GB Fixed HDD, 4GB RAM, and 256GB video memory with 3D accelleration. But I honestly do not expect to be doing with it very much more than keeping my resume up to date and in MS Word format for the recruiters that are *.rtf-illiterate.

So have I been overly generous to a fault with my resource allocation to this particular guest? What would be the minimum allocations for the useage described above, and what would be an appropriate allocation if I wanted a little comfort-room to say, dowload a DVD image and burn it to disk?

Along the same line of questioning... another vm I have is running Win Vista Ultimate 64-bit and Office 2007. I need this one primarily for my son's online school... some of their interface tools are not compatible with any browsers other that IE 7 & 8 or Firefox 3.6. So the older OS makes FF 3.6 possible. Again, I don't have to download a lot of files, nor do I need to run many apps, other than web-browsers and theirlive-classroom software tool. So have I been wastefully generous with my physical resources by allocating 4GB RAM and 40GB fixed hdd?

Suppose I wanted to run both of these guests simultaneously? I realize that would be impossible when each takes 4 GB of the toal 8GB of memory. But, given the useage info provided above, could I scale back the memory allocatio on the two guests to something that would allow them both to run comfortably at the same time, while still allowing me to perform daily Internet and OOo tasks on the Ubuntu host?

Is it possible that perhaps operating systems and programs do not have quite the same requirements on a virtual machine as they do on their own hardware?

You should be able to run both just fine with 2GB of memory apiece. The only thing that might slow down is heavy CPU usage by the guests so just keep an eye on that.

is it possible to "shrink" a fixed hard drive, other than delete and rebuild it?

Use CloneVDI for this. The image will be cloned, no new guest installation.

stefan.becker wrote:Use CloneVDI for this. The image will be cloned, no new guest installation.

How will cloning shrink the size of the fixed hdd?

It won't. It can compact the drive but AFAIK there is no easy way to shrink the physical size of the drive.
You can shrink the partition to restrain the amount of space actually used, but this is dangerous.

Well... if you clone a fixed size image to dynamic (which is what happens if you clone using CloneVDI) then you can expect the clone to be physically smaller. If you set the "Compact" option then it will be smaller yet. If you want to permanently constrain the size of the hdd you would have to shrink the partition using gparted, and then clone using CloneVDI with Compact enabled.

My feeling is that you'll probably find that you don't need to shrink the partition: just the conversion to dynamic will make the size manageable. There are very few good reasons to go for fixed (none that I can remember on the spot!). Most of the things you will read about "fixed" are invalid myths.

thx mpack. the only reason i chose "fixed" was due to thinking in terms of physical disk requirements for OS. But I am beginning to see that I really do not need to be too concerned about that. it sounds as though, if I just create with dynamic disk, then VB will adjust disk size automatically as needed... so if I end up only installing a total of 20GB of data, then that's all the space it will use (plus VB "overhead" ) on the physical storage volume.