What's the ideal size of a virtual hard drive for a Virtual Machine

When you create a vm for Virtual Box, you must select how big the virtual HDD is. By default the virtual hdd is set at 8 gb (which actually only takes up 2 gb of real hdd space). I am running out of hdd space (my HDD only has 80 gigs of free space left...much of the space allocated to VMs and computer games...i need to download more computer games and other free stuff lol).

The ISO image of most operating systems take up about 2 gigs of HDD space. The OS itself of Backtrack, Tails, XP and 7 take up a gig or two of HDD space. I think 8 gb is a bit excessive unless I plan on storing many files in the virtual hdd.

So what is the ideal size of a virtual HDD? Can I check how much space an OS will take on a virtual HDD? I plan on installing Linux Backtrack. Can I check how much virtual HDD space Linux Backtrack takes up before installing it and then allocate an extra gig or two of virtual HDD space to the Backtrack VM, instead of dedicating way too much extra HDD space? An extra 5 or 6 gigs of virtual HDD space is way too much.

Let's say the Backtrack OS itself only takes up 2 gigs. So the virtual HDD only needs to be 3 to 4 gigs--one to two gigs of extra HDD space. No need for a 8 gig virtual HDD, since 6 gigs of free space is excessive. Hopefully this question makes sense. Hope you guys can help answer my question about how big I should make the virtual HDD space.

 

I typically use dynamically-sized virtual disks with 100-200 GB maximum. There's a little performance hit vs fixed-size disks, but not enough to make up for the space commitment. If a VM is getting too big for some unplanned reason, I can just move it to other hardware.

 

Should Linux guests have smaller max dynamic size for their scattered files all over the disk and constant updates? I already see multiple instances of 3+ GB more space allocated than what the OS show as free space with an 8 GB limit.

 

That takes up way too much space man. LOL I barely have 300 gb of space on my HDD in total and there is barely any HDD space left on my HDD for games and other stuff I'll like to store on it.

 

I mean I don't mind having large virtual machines, but I don't want my VMs to take up all of the remaining space I have left on my HDD, which can be used to store other stuff.

 

I usually make em 20GB's just to try out random things. Im pretty sure it doesnt matters, just make sure it will be enough for what you will do.

 

A 200 GB dynamic disk holding 3 GB is no larger than a 5 GB dynamic disk holding 3 GB.

The only problem is that it doesn't get smaller after you delete stuff from the VM.

Alternatively, you can attach additional virtual disks if you need more space, and then remove them later. But that's a little complicated if you want full-disk encryption.