The following demo scripts (scenarios) can be used to show advantages of OpenVZ.
Contents
Full VE lifecycle
Create VE, set IP, start, add user, enter, exec, show ps -axf output inside VE, stop, and destroy. It should take two minutes ("compare that to a time you need to deploy a new (non-virtual) server!"). During the demonstration, describe what's happening and why.
Here are the example commands needed:
# VE=123 # IP=10.1.1.123 # sed -i "/$IP /d" ~/.ssh/ # time vzctl create $VE --ostemplate fedora-core-5-i386-default # vzctl set $VE --ipadd $IP --hostname newVE --save # vzctl start $VE # vzctl exec $VE ps axf # vzctl set $VE --userpasswd guest:secret --save # ssh guest@$IP [newVE]# ps axf [newVE]# logout # vzctl stop $VE # vzctl destroy $VE
Massive VE creation
Create/start 50 or 100 VEs in a shell loop. Shows fast deployment and high density.
Here are the example commands needed:
# time for ((VE=200; VE<250; VE++)); do \ > time vzctl create $VE --ostemplate fedora-core-5-i386-default; \ > vzctl start $VE; \ > done
Massive VE load
Use VEs from previous item — load those by ab or http_load. This demo shows that multiple VEs are working just fine, with low response time etc.
# for ((VE=200; VE<250; VE++)); do \ > vzctl set $VE --ipadd 10.1.1.$VE --save; \ > done
On another machine:
# rpm -ihv http_load #
FIXME: http_load commands
Live migration
If you have two boxes, do "vzmigrate --online" from one box to another. You can use, say, xvnc in a VE and vncclient to connect to it, then run xscreensaver-demo and while the picture is moving do a live migration. You'll show xscreensaver stalls for a few seconds but then keeps running — on another machine! That looks amazing, to say at least.
FIXME: commands, setup, vnc template.
Resource management
Below scenarios aims to show how OpenVZ resource management works.
UBC protection
fork() bomb
# while [ true ]; do \ > while [ true ]; do \ > echo " " > /dev/null; > done & > done
We can see that number of processes inside VE will not be grow up. We will see only increase of numproc or kmemsize fail counters in /proc/user_beancounters.
dentry cache eat up
FIXME
CPU scheduler
Create 3 VEs:
# vzctl create 101 # vzctl create 102 # vzctl create 103
Set VEs weights:
# vzctl set 101 --cpuunits 1000 --save # vzctl set 102 --cpuunits 2000 --save # vzctl set 103 --cpuunits 3000 --save
We set next cpu sharing VE101 : VE102 : VE103 = 1 : 2 : 3
Run VEs:
# vzctl start 101 # vzctl start 102 # vzctl start 103
Run busy loops in VEs:
# vzctl enter 101 [ve101]# while [ true ]; do true; done # vzctl enter 102 [ve102]# while [ true ]; do true; done # vzctl enter 103 [ve103]# while [ true ]; do true; done
Check in top that sharing works:
# top COMMAND %CPU bash 48.0 bash 34.0 bash 17.5
So, we see that CPU time is given to VEs in proportion ~ 1 : 2 : 3.
Disk quota
# vzctl set VEID --diskspace 1048576:1153434 --save # vzctl start VEID # vzctl enter VEID [ve]# dd if=/dev/zero of=/tmp/tmp.file bs=1048576 count=1000 dd: writing `/tmp/tmp.file': Disk quota exceeded