Here is the list of some useful OpenVZ commands which should be run from the main node :
1. To fetch the consumption of disk for each container in the node along it’s hostname and ctid
vzlist -H -o veid,hostname,diskspace | awk '{ printf("%d\t%s\t%.2f GB\n", $1, $2, $3/(1024*1024))}'
2. To find the load average of each container on the node. Pretty useful command to find the culprit.
vzlist -o ctid,laverage,hostname
3. Using PLOOP containers? Use this command to free up some space.
vzctl compact [ctid]
4. Change the number of CPU allocated to a container by the following command
vzctl set [ctid] --cpus 4 --save
5. Command to modify the disk space allocated to a container
vzctl set [ctid] --diskspace 480G:500G --save
6. Command to change password of a container (including root user)
vzctl set [ctid] --userpasswd [username]:[password]
7. Command to change/set hostname of a container.
vzctl set [ctid] --hostname server.hostname.com --save
8. Command to adjust/allocate the RAM for the container.
vzctl set [ctid] --ram 1G --swap 2G --vm_overcommit 2 --save
[ctid] with 1 GB of RAM, 2 GB of swap, and (1+2)*2, i.e. 6 GB of virtual memory. That means this container can allocate up to 6 GB of memory, but can’t use more than 3 GB.
You can set vm_overcommit manually as well by using the following commands
64MB Guaranteed, 128MB Burstable
vzctl set [ctid] --vmguarpages 64M --save
vzctl set [ctid] --oomguarpages 64M --save
vzctl set [ctid] --privvmpages 64M:128M --save
1024MB Guaranteed, 2048MB Burstable
vzctl set [ctid] --vmguarpages 1024M --save
vzctl set [ctid] --oomguarpages 1024M --save
vzctl set [ctid] --privvmpages 1024M:2048M --save
9. Starting, Stopping, Restarting, and Querying Status of Container
Start a Container
vzctl start [ctid]
Stop a Container
vzctl stop [ctid]
Restart a Container
vzctl restart [ctid]
Status of a Container
vzctl status [ctid]
10. Listing Containers
vzlist -a
11. Deleting Container
vzctl stop [ctid]
vzctl destroy [ctid]
12. Disabling Container
vzctl set [ctid] --disabled yes --save
13. Suspending Container
vzctl chkpnt [ctid]
14. Running Commands in Container
vzctl exec [ctid] /etc/init.d/sshd status
openssh-daemon is stopped
vzctl exec [ctid] /etc/init.d/sshd start
Starting sshd: [ OK ]
vzctl exec [ctid] /etc/init.d/sshd status
openssh-daemon (pid 9899) is running…
15. Setting SWAP Space for the container
4GB SWAP Space
vzctl set [ctid] --swappages 4G:4G --save
Extras
VZCTL Log File Location: /var/log/vzctl.log
