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Re: [Xen-users] 8GB RAM on a 32Bit Dom0 - Xen 3.2

On Wed, 2013-07-03 at 11:13 +0200, ml ml wrote:
> Hello Lan,
> thanks for your reply. I am aware that i need to leave enough ram for
> my Dom0. I was just wondering if the concept all together works:
> Dom0 = 32Bit  but 8GB Ram (in 32Bit can only handle up to 4GB?!)

A 32-bit PAE kernel (which is required to run on Xen 32-bit anyway) can
handle up to ~16GB of RAM in total, although obviously any one process
can only have up to 4GB.


> Cheers,
> Mario
> On Wed, Jul 3, 2013 at 10:54 AM, Ian Campbell
> <Ian.Campbell@xxxxxxxxxx> wrote:
>         On Wed, 2013-07-03 at 10:41 +0200, ml ml wrote:
>         > Question: Does this make sense? Can i assign almost all my
>         8GB to my
>         > guests? Or will this cause problems?
>         Assigning up to, say, 7GB to guests to ballooning dom0 down to
>         1GB ought
>         to be fine. Below that you run the risk of dom0 running short
>         of memory
>         because some data structures are sized at boot to fit the 8GB
>         size and
>         cannot be shrunk when ballooning. The point at which this can
>         happen
>         varies though so you could experiment, e.g. you might be fine
>         going down
>         to 512M in dom0.
>         If you run into trouble then you could use the dom0_mem=
>         hypervisor
>         option to reduce the maximum amount of RAM dom0 can see, which
>         would
>         cause those static datastructures to be proportionately
>         smaller. Of
>         course this means that you cannot easily use that RAM for dom0
>         when no
>         domains are running, so whether this is appropriate depends on
>         your
>         usecase.
>         Ian.
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