I know when running vm software like Oracle VM VirtualBox you can have the option to make your HD expand with the system. 

Is there a way to make that happen with unRaid?

I'm not sure exactly what you are asking, but yes, if you create a VM using defaults it will set up a sparse vdisk image, with a max size of whatever you specified, but the file will only occupy whatever is used inside the image on disk. There are a couple topics on passing that sparseness through to the VM, so that the OS will actively trim deleted files and pass the space back to the host. If not then as the image gets used and fragmented it will grow to occupy the max size.

 

If that's not what you are asking, you need to ask a more specific question.

Its opposite of what you are saying. 

So lets say the os/software is a total of 20gb then you install some more stuff and it goes to 30gb. 

The vm image will then go from 20gb to 30gb. The vm image will expand with the system.

Evidently we are talking at cross purposes, because that is exactly what I said. You set up the VM, specifying a 50GB image. You install the OS and whatever, which takes up 20GB. The total size on disk is 20GB. You then add 10GB more data to your VM, and it will now occupy 30GB of space. The 50GB initial specification is just the maximum that the image will be allowed to eventually occupy, it's not what it takes up on the disk.

 

If, however, you copy that vdisk image to a location that doesn't support sparse files, or with a method that doesn't support sparse files, and it will take up the entire 50GB.

Nope. Not what I meant. I'm sorry if I am confusing you. 

Say you set the VM image to max of 30GB

The OS install is 25GB and then you go to install your files and software. However it is 10GB. So what would happen is once you hit the 30GB instead of the drive showing FULL. It will expand with the needed space. So the VM image will expand to 35GB automatically. 

 

I know when I do a Windows VM it allocates all 30GB at one go (if set that as the drive space). So in your scenario. By looking at total HD/SSD available space it will show a full 30GB taken. Not 25GB taken that the OS install. 

25 minutes ago, demonmaestro said:

I know when I do a Windows VM it allocates all 30GB at one go (if set that as the drive space). So in your scenario. By looking at total HD/SSD available space it will show a full 30GB taken. Not 25GB taken that the OS install. 

My vdisk size:

61G -rw-rw-rw- 1 root   users 160G Jun 27 19:46 vdisk1.img
11M -rwxrwxrwx 1 root   root  1.0G Apr 28 17:29 vdisk2.img*

61G taken actually used on the disk, but 160 Gig allocated to Windows

 

26 minutes ago, demonmaestro said:

Say you set the VM image to max of 30GB

The OS install is 25GB and then you go to install your files and software. However it is 10GB. So what would happen is once you hit the 30GB instead of the drive showing FULL. It will expand with the needed space. So the VM image will expand to 35GB automatically.

It can't (and it shouldn't) because you've set the max size to be 30G.  If you want it to be able to expand to 35G, you have to tell it the max size is 35G

root@Tower:/mnt/user/domains/Office7# ls -alsh   
total 37G
  0 drwxrwxrwx 1 nobody users  24 Jun 16  2016 ./
  0 drwxrwxrwx 1 nobody users 119 May 28 23:52 ../
37G -rwxrwxrwx 1 root   root  50G May 20 11:27 vdisk1.img*

In this example I have a windows 7 pro install that has a 50G vdisk1.img file currently occupying 37G of space, because of deletions and other activity that hasn't been trimmed.

 

 

You might also want to look at this;

This is the reason our @jonathanm and my vdisks are relatively small.  Without this, Your vdisk will only ever grow (until it reaches the max size) and will never shrink.