# Setting max memory of a Xen Dom0

I’ve had some issues with Xen crashing when I wanted to create a DomU for which the Dom0 had to shrink (see bug report). Therefore, it’s better to force a memory limit on the dom0. That is done with a kernel param.

# Start dom0 with less RAM
GRUB_CMDLINE_XEN_DEFAULT="dom0_mem=512M"

And make sure you disabling ballooning of dom0 in /etc/xen/xend-config.sxp:

(enable-dom0-ballooning no)

Then run update-grub2 and reboot.

1. Comment by Rowan Rodrik
On November 28, 2011 at 21:29

Dude, I recall you saying at some time that it’d be impossible to beat my post count, because I had such a big head start… Well, a few posts ago, you did. Just sayin’. 😉

2. Comment by Gabriel
On February 15, 2012 at 01:32

neat, this was the piece of the puzzle that was missing on my setup.

I’ve disabled dom0 ballooning entirely to try and avoid resizing crash issues (what a bad bug ..) but the dom0 was then taking all the available space for itself and wouldn’t let it go for VMs.

now it’s restricted to 500Mb and the rest is available to domUs.

3. On Feb 28, 2013 at 14:45

[…] (network-script network-bridge) (dom0-min-mem 196) (dom0-cpus 0) (vnc-listen '127.0.0.1') (vncpasswd '') (Also, don’t forget to disable ballooning and setting a max memory.) […]