Dynamically Allocated Storage not reaching Max

[just4lizzy]

I have a feeling there are a lot of threads like this already, but I am a new user and the tips aren't working for me. I have a dynamic storage .VDI that currently has an actual size of 30.41GB and virtual size of 50GB (The file in my Mac HD is 32.65GB). I have about 58GB left of storage on my Mac, so there should be enough room for the .VDI to reach 50GB if needed? I was under the impression that with dynamically allocated storage, the storage can adjust automatically as needed but only up to the maximum virtual size.

I'm trying to download and install a program that is about 7GB and I get an error on the guests OS that there isn't enough storage. I've tried the modifyhd --resize method, and I get an error that says "Resize medium operation for this format is not implemented yet!" Am I doing something wrong?

[socratis]

You didn't mention your guest so we can't help you with details, but if it's a Linux one check from within the guest where it allocates the space. Most of the people forget about the 'swap' partition which takes a considerable amount of hard disk space.

So, we'll need some more details: full host version, full VirtualBox version, full guest version and details and the complete command and output of the modifyhd error that you got.

[mpack]

One glance at the partition map for the drive would probably be enough. What's the default swap size these days? Is it still 2 x RAM? So if, let's say, the guest had 8GB RAM when the OS was installed then the swap partition would be 16GB. A 50GB drive would have a user-usable apparant filesystem of 34GB.

Or, ask the guest OS what size the filesystem is. It'll tell you something around 34GB, because the swap partition isn't part of the users filesystem.

This has nothing to do with being virtual or dynamically expanding. You'd see exactly the same behaviour if you installed Ubuntu on a physical PC with a 50GB drive (and 8GB RAM): i.e. you'd run out of filesystem space at around 34GB.

[Perryg]

Not to mention LVM if that is what they are using and what about compression of the new program? It would need to be decompressed before installing ( double the size needed ) and also compiling if it were needed which would also require double the space initially. Point is you should never try to use all of the drive space. There needs to be some at the end to work with.

[just4lizzy]

I ended up just extending the partition on the guest to fill up the rest of the 50GB that was allocated to it in the .vdi. Solved my problem, but didn't really address why the storage wasn't acting like it was dynamic, unless I misunderstand the definition.

I'm running Max OS X 10.12.6, VirtualBox 5.1.28 r117968, and the Guest is running Windows 10 Pro (v1607?).

I think the resize function didn't work because I was trying to resize to 40GB, which is smaller than the 50GB I already gave it. I think I mistakened the function for extending the partition on the guest.

[socratis]

Either your description was off, or I missed something. The original question was "why doesn't this expand to it's maximum". Then you came back with "I resized the partition". What??? If you created a 50 GB hard disk and you installed your Win10 guest, then it would have seen a 50 GB hard disk, no more, no less. So why would you need to resize the partition? And why did you need the VBoxManage command to resize the HD?

[mpack]

Did you take that one glance at the partition map that I recommended? It sounds like not.

Incidentally, VirtualBox knows absolutely nothing about the meaning of any data you store on a drive. That includes metadata such as the partition map. So if the disk has a partition map you don't approve of then you should be looking at what you did when you installed the guest OS, there is no need to look elsewhere.