[15:07] <Alexey_> Ваше здоровье! 🍺
[15:19] <lotuspsychj3> !english | Alexey_ 
[18:33] <pvh_sa> Hey there... I have a 22.04 server (recently upgrade) that is hosting some VMs using libxl (Xen driver) in libvirt - trying to start a VM fails with "Failed to balloon domain0 memory" - does anyone know what this means and how to fix it?
[18:36] <ChmEarl> pvh_sa, its usually the xen hypervisor cmdline lacks max in dom0_mem=
[18:37] <pvh_sa> thanks! let me look into that
[18:37] <ChmEarl> see the hypervisor lines in /etc/default/grub
[18:38] <ChmEarl> GRUB_CMDLINE_XEN_DEFAULT=
[18:39] <pvh_sa> ok - so this is going to be the max RAM that all VMs can consume (together)?
[18:39] <pvh_sa> or... the max memory used for the host?
[18:41] <ChmEarl> max for host
[18:42] <pvh_sa> ok let me carve off 16 GB for that and leave the rest for VMs. I'm just using this machine for a few legacy VMs (the main stuff is over on OpenStack)
[18:45] <pvh_sa> so reading some docs... Xen guests also have access to the balloon device to negotiate memory dynamically
[18:46] <ChmEarl> pvh_sa, mine has: dom0_mem=4096M,max:4096M
[18:47] <pvh_sa> so the Xen hypervisor (dom0) runs in 4GB?
[18:47] <ChmEarl> so that any VM balloon won't hurt my dom0
[18:47] <ChmEarl> it can be much lower, like 1024M
[19:00] <ChmEarl> pvh_sa, sudo xl dmesg | grep Command
[19:01] <ChmEarl> shows hypervisor cmdline
[19:09] <pvh_sa> thanks... that resolved the balloon error - now its giving "libxenlight failed to create new domain" - the libxl log is saying "libxl__get_domid: failed to get own domid"
[19:10] <pvh_sa> I see others found this was related to stale config - https://askubuntu.com/questions/1239384/xen-cannot-start-domains-after-upgrading-from-18-04-to-20-04