virtualbox.org

I am trying to install W2K as a guest OS on Windows XP3 host and I get the dreaded HostMemoryLow error. This machine has 2G of memory, of which 1.2 are physically available when the error occurs, and I only requested 512M for the VM, so this is totally baffling!

I did search the forums but did not find any good answer.

Which VBox version?

The latest one, i.e., 2.1.4. I was able to create the VM with 256M but that may not be enough for futures uses.

Resources reported to be available are not always correct, the host cache eats away more ram when more (other) resources start doing stuff like starting a VM. See if you can disable some Host services or add more ram.

I am once again getting the error while trying to start a second VM, also of 256M, while there are still 1.1G available. It really looks like you have a bug here.

"Resources reported to be available are not always correct" Come on, a 850M discrepancy? VBox says there is less than 256M left, Task Manager says there is 1.1G: that is not credible.

Anyway, is there a tool that will report memory usage as seen by VBox?

Could be a bug yes, get processexplorer, it will show you exactly how your ram is used and by who.

Process Explorer (the SysInternals tool, right?) agrees with Task Manager to within 1M: they both say there is 1.2G left.

Yes that one, but what happens to your ram when starting that VM? and who's grabbing it?

Before starting and after closing it the VM, PE reports 2G total, 1.2G available, 13G system cache. While the error dialog is showing the figures are the same except for available, which drops to 1.2G. What information do you need to know exactly and how can I get it?

All other applications can function within these parameters: none seems to think that memory is exhausted. Thus even if this is not a VBox bug it is (from a practical point of view) a severe drawback.

1.2G available,
1.3G system cache
?
This makes sense when running out of ram... system cache is always the culprit here, it sometimes doesn't release enough or too late.

Additional:
You have to see this in a liniar fashion, if one block(application) registers X amount of ram then system cache will try to reserve cache for it in a liniar fashion which is about 25% of X, this then has to be taken away from the OS, where Z=Y(OS)+25%(Y)+Cachereserve-(X(VM)+25%(X)), you won't see that happening until the VM starts running. System cache will shoot up in use liniar to what the VM is requesting. Not even mentioning what (shared)video ram use can do when more then 1 graphical instance is doing its thing.

That still doesn't explain why I can start other applications but not VBox.

No it doesn't really explain that the easy way, all you can try is disabling services that seem to use alot of ram.

I have almost nothing else running. The OS is responsible for most of the memory consumption.

The reason you can't start another VM is because you are running out of physical RAM. VB only uses RAM. Other programs can use your pagefile. Check how much RAM you are using. On my system, I have 3 GB of RAM, no page file and by default I'm already using more than 700 MB of RAM. With a VM of 512 RAM, I climb up to 1.5 GB in use. You can easily see how much physical RAM you have and are using, by opening the Windows Task Manager, go to the Performance tab and check the values under Physical Memory (K). That is the upper right block, of the 4.