Demo scripts

The following demo scripts (scenarios) can be used to show advantages of OpenVZ.

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