User`s guide

Advanced Tasks 71
Rebooting Virtual Private Server
When you issue the reboot command at your Linux box console, the command makes the
reboot system call with argument ‘
restart’, which is passed to the computer BIOS. The
Linux kernel then reboots the computer. For obvious reasons this system call is blocked inside
Virtual Private Servers: no Virtual Private Server can access BIOS directly; otherwise, a reboot
inside a VPS would reboot the whole Hardware Node. That is why the
reboot command
inside a VPS actually works in a different way. On executing the
reboot command inside a
VPS, the VPS is stopped and then started by a special script (
/etc/sysconfig/vz-
scripts/vpsreboot
) which is executed periodically (every minute by default) by the cron
daemon. Cron configuration to run the script is in the file
/etc/cron.d/vpsreboot.
If you want a Virtual Private Server to be unable to initiate reboot itself, add the
ALLOWREBOOT=”no” line to the Virtual Private Server configuration file
(
/etc/sysconfig/vz-scripts/vps_id.conf). If you want to have VPS reboot
disabled by default and want to specify explicitly which Virtual Private Servers are allowed to
reboot, add the
ALLOWREBOOT=”no” line to the OpenVZ global configuration file
(
/etc/sysconfig/vz) and explicitly specify ALLOWREBOOT=”yes” in the corresponding
Virtual Private Server configuration files.