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Do you think that me using 512MB of ram for my VM Base memory with Windows XP when I am running 2.7GB of ram is okay? or should I return it back to 192MB?

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According to Ubuntu reqs it would be enough if You have left for it 1GB of RAM. For example I have done something like this:

I have got a PC with 4GB of RAM, host is Ubuntu and the Guest is Windows 7. When I need to use Windows it means I need Windows at the moment, and not Linux, so my Win7 WM has 3GB of ram. The Linux is just working to run VM. But I don't run any apps on Linux in such situation.

For me such solution works really fine. So I think You could even enlarge the amount of RAM given to Your XP machine if necessary.

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The post below mine says if I notice a change in swap I should lower it? so should I? or is swap okay? – Alex Poulos Feb 18 '12 at 7:37
Your Ubuntu will use swap if it will be forced to handle more data than it is possible for it to place in RAM. What happens then is that OS will write something like an image of piece of RAM onto the disk - exactly in the swap partition. The problem with this, is that it makes Your PC work slower, as it has to read some data from (generally slow)disk instead of fast RAM. However, due to my expierence if You run Your Windows guest and leave Ubuntu You will be able to work on Your XP without any problems. Just don't open apps on Ubuntu while using VM. – Misery Feb 18 '12 at 7:45
Run windows guest and leave Ubuntu? almost sounds like dualbooting. – Alex Poulos Feb 18 '12 at 10:49
Not really. It depends on what You need. If You want to run two systems in parallel, and to work very well, then the only option is to buy a proper hardware. For example i7, 2x GTX 480 and at least 16GB of RAM. – Misery Feb 18 '12 at 12:50

That completely depends on what else you run at the same time, but it should be fine. Track your Linux memory usage with free -m in a terminal window and if you start using even the slightest amount of swap, lower the RAM setting for the VM again.

When the OS runs out of actual RAM memory (which is, relatively speaking, blazingly fast), it has to use swap memory, which is a file or a dedicated partition on your harddrive (which is really slow, relatively speaking -- hundreds of times slower than RAM). Obviously, you don't want your system to run into this situation. Hypervisors (the programs that host virtual machines) tend to allocate the whole amount of RAM that you set aside for the virtual machine since allocating it bit by bit (what normal programs tend to do) would negatively impact the performance of the virtual machine guest OS.

The output of free -m looks about as follows:

username@hostname:~$ free -m
             total       used       free     shared    buffers     cached
Mem:          4025       1893       2132          0        306        956
-/+ buffers/cache:        630       3395
Swap:         4769          0       4769

As you see, the swap is not used in this case ("used" is 0). This is fine. But if you run many RAM-intensive programs, such as Firefox with a bunch of tabs (especially ones with Flash content), an image editor, and your virtual machine together, then you might be taxing your system's resources. If you computer feels like it's getting slower, you now know where to check.

I would also like to comment on the reply that quotes Ubuntu's minimum system requirements: these do not take your running applications into account, so they refer to what you need to just get the basic Ubuntu environment up and running. Any application you run on top of that environment will also require resources.

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what exactly do you mean the slightest amount of swap? like how do I know that and what exactly does that mean if it does start? – Alex Poulos Feb 18 '12 at 7:37
I've updated my answer to be more informative, @AlexPoulos, check it out. – Lakritsbollar Feb 18 '12 at 8:47
So, how will I make sure for sure that I'm safe? because now Im worried to run it at 512MB... – Alex Poulos Feb 18 '12 at 10:52
Swapping is just suboptimal from a performance point of view, not harmful. :-) Don't worry, just try and see and if it feels sluggish, close a few programs or lower the RAM setting. – Lakritsbollar Feb 18 '12 at 11:09

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