I have an older Dell C521 computer with a decent processor and 8GB of memory. I no longer use the machine but would like to have it available for testing operating systems using VirtualBox.
When testing I want as much of the system resources available for the "guest" operating system as possible.
What base operating system should I use to get the most bang for my buck out of Virtualbox?
I was thinking Ubuntu, but it would be nice if there was something even more minimal.
While a standard Ubuntu desktop install uses around 400-700MB you could try a Ubuntu Server install. The overheads are drastically reduced as there is no GUI. I do not have any expereince with other linux types so cannot say in regards to their effectiveness.
Do you have to use VirtualBox? Consider using a bare-metal virtulisation package such as ESXi (VirtualBox, on the other hand, needs a OS installed on it already).
You could install Ubuntu and still go for a lightweight GUI by replacing unity. In case you don't opt for Ubuntu there are flavors such as lubuntu which can run even on as low as 256 mb of ram.
Default Ububtu setup (i.e. with Unity DE) could barely be considered lightweight. If you stick to Ubuntu, you can install Ubuntu Server, and, if necessary, some lightweight desktop environment (LXDE, for example). The OS itself does not consume a lot of resources, so it does not matter that much.
However, if the machine will be used for virtualization only, you could use bare-metal vistualization solutions, such as ESXi, which are essentially minimal Linux setup + virtualization solution.
Ubuntu Server should do it, and so will any Linux distro. You do not need to run a GUI: the VMs can be managed with something like phpvirtualbox.
But for a machine that will only be used for virtualization, ESXi should be better. However, ESXi requires hardware virtualization support. Looking at Dell's datasheet for the C521, it's unclear whether the CPUs used in this model have this feature.
