I'm running into a problem on my xen 4.0.1 server (debian squeeze)
My host has 32G of memory, Domain-0 has 2048 M assigned to it. (scaled down with xm mem-set Domain-0 2048) top in Domain-0 confirms this.
I created a virtual machine config file (using xen-tools) with the following options:
memory = '512' maxmem = '2048'
Both host and guest machines are running the standard 2.6.32-5-xen-amd64 debian kernel.
'xm create' creates a virtual machine with 512MB of memory as expected.
Then 'xm mem-set domU 1024' will not expand the memory to 1024MB
running 'xm mem-set domU 400' does set the memory to about 400MB
Then 'xm mem-set domU 1024' will expands the memory back to 512MB
Based on this, you would say that xm ignores the maxmem and silently sets maxmem to 512, but in the output of xm top the MAXMEM column reads 2G. the MEM column will not go over 512M.
The output of xm list tells another story, it shows 1024 when I 'xm mem-set domU 1024'.
I've googled myself all away around the internet for this issue and found that most people don't scale back Domain-0. I know I've seen a bugreport about the issue I'm experiencing, but can't find it anymore.
Does anyone see what I'm doing wrong here?
Hmm.. I just upgraded my kernel to the one provided by debian backports. The issue has gone.