Question on maximizing Virtual PC performance

sschmidlap

Hello folks. Host OS is Win XP SP3 with 2 GB physical RAM. When running virtual machines, I have found I am limited to 1 GB RAM total. For example, I can have 4 VMs running if they only have 256 MB each or 1 VM running with 768 MB and another with 256 MB but can't get past 1 GB total for virtual machines. Does anybody have any ideas or tricks I can try to be able to allocate more total RAM to the virtual machines? Thank you.

JDMurray

If you try to run VMs that eat up more than 1GB of RAM, do you you get an error message that complains about there not being enough memory available on the host when you start up that last VM? And look in Task Manager to see how much memory is your XP host is eating up. A clean installation of XP with no apps running should only need 250-300MB of RAM.

sschmidlap

Yes, I get the message saying there is not enough physical memory on the host. Right now I am running Server 2003 VM with 256 MB and Vista VM with 768 MB. I try to start a 3rd VM with 256 MB Ram and get the error. I looked in Task Manager like you said. Seems odd... when I roughly add up the running processes and memory usage in my head it seems like a total of just 200-300 MB RAM being consumed by the host. So, let's say 300 MB for the host and 1 GB for the VMs. 256 MB is shared as video memory I believe so I can't count that as available. I still show just under 400 MB physical memory available in Task Manager Performance but I again tried to open a VM using 256 MB Ram and get the error.
P.S. I know the best solution is to just get more physical RAM. I just have an older motherboard with only 2 slots for RAM. I am running XP x64 on the host so I should be able to put, say, 2 8 GB sticks in there I presume. 1)I am trying to put off spending any more money on hardware for the time being, and 2)according to the specs from HP/Compaq the motherboard only supports 2 GB Ram total. Not sure how this could be, it's a 64 bit processor. Maybe they just say that since the machine ships with a 32 bit operating system? I mean, as long as you have a 64 bit CPU and OS you should be able to add as much RAM as you have slots for right?
One last question, PLEASE... if I have to choose between upgrading current machine with RAM or a CPU that supports hardware virtualization (like an affordable Pentium D) which do you think would show greater performance boost for VMs? I am thinking the CPU. I guess I don't really need to run more than 2 VMs right now anyway (on one host) Thank you sir.

Devilsbane

sschmidlap wrote: »

Hello folks. Host OS is Win XP SP3 with 2 GB physical RAM. When running virtual machines, I have found I am limited to 1 GB RAM total. For example, I can have 4 VMs running if they only have 256 MB each or 1 VM running with 768 MB and another with 256 MB but can't get past 1 GB total for virtual machines. Does anybody have any ideas or tricks I can try to be able to allocate more total RAM to the virtual machines? Thank you.

RAM is the most needed resource for running multiple VM's. Processor power can help but it is really the ram that limits your VM. And you never want to make your hosting os short. That just spells disaster. As you run out of RAM your computer pages it to the HDD. HDD is about 1,000 times slower than RAM. So your going to slow to a halt and eventually crash the entire system, which is bad.

The only thing you could really do is add ram to your computer. It is pretty cheap unless your looking at ddr3. And since your os is xp your probably using ddr2 or ddr depending on the age.

Edit: Check out new egg for prices, don't waste your money at best buy or something like that. I bought 4GB of ddr2 about a year ago for like $50. A small price to pay to double the ram in my old laptop.

Also, don't forget that a 32 os can at best utilize 4gb of ram. Usually somewhere in the 3.5 range since different hardware configurations and decrease the amount available. Your also going to want to make sure the MB supports the extra ram.

earweed

I'm kind of inthe same boat you are. I have an HP which they say the motherboard will only support 2GB RAM. I'm running Vista Ultimate (32 bit) host but haven't had the error messages. If I'm running 3 2k8 VM's (512MB each) they just slow way down so I just try to limit myself to 2.