vzctl(8) Virtual Private Server vzctl(8)

vzctl - utility to control Virtual Private Server.

vzctl [flags] create vpsid --ostemplate name] [--config name] [--private path] [--root path] [--ipadd addr] [--hostname name]

vzctl [flags] set vpsid [parameters] [--save]

vzctl [flags] destroy | mount | umount | start | stop | restart | status | enter vpsid

vzctl [flags] exec | exec2 vpsid command [arg ...]

vzctl runscript ve_id <script>

vzctl --help | --version

Utility vzctl runs on Hardware Node (HN) and performs direct manipulations with virtual private server (VPS).

Virtual Private Servers can be referred to by numeric vpsid. Note that VPS ID <= 100 are reserved for OpenVZ internal purposes.

These flags can be used with almost any option.
--quiet
Disables logging to log file and screen.
--verbose
Sets logging level to maximum value.

set vpsid [parameters] [--save]
This command sets various VPS parameters. If flag --save is given, parameters are saved in VPS configuration file vps.conf(5). If VPS is currently running, vzctl applies these parameters to VPS.

The following options can be used with set command.

Miscellaneous parameters
--onboot yes|no
Sets whether this VPS will be started during system boot up. VPS will not be auto-started during system boot up unless this parameter is set to yes.
--root path
Sets the path to root directory for this VPS. This is essentially a mount point for VPS root. Value must contain string $VEID, which will be substituted with numeric VPS ID. Changing this parameter is not recommended, better edit vz(5) global configuration file.
--userpasswd user:password
Sets password for given user in VPS, creating the user if it does not exists. Note that this option is not saved in configuration file at all (so --save flag is useless), it is applied to VPS (by modifying its /etc/passwd and /etc/shadow files).

In case VPS root is not mounted, it is automatically mounted, then all appropriate file changes are applied, then it is unmounted.

Note that VPS area should be created before using this option.

--disabled yes|no
Disable VPS start. For force start disabled VPS option --force can be used.
Network related parameters
--ipadd addr
Adds IP address to given VPS. Note that this option is incremental, so addr are added to already existing ones.
--ipdel addr | all
Removes IP address addr from VPS. If you want to remove all addresses, use --ipdel all.
--hostname name
Sets VPS hostname. vzctl writes it to the appropriate file inside a VPS (distribution-dependent).
--nameserver addr
Sets DNS server IP address for VPS. If you want to set several nameservers, you should do it at once, so use --nameserver option multiple times in one call to vzctl, as all the name server values set in previous calls to vzctl gets overwritten.
--searchdomain name
Sets DNS search domains for VPS. If you want to set several search domains, you should do it at once, so use --searchdomain option multiple times in one call to vzctl, as all the search domain values set in previous calls to vzctl gets overwritten.
Resource limits
The following options sets barrier and limit for various user beancounters. Each option requires one or two arguments. In case of one argument, vzctl sets barrier and limit to the same value. In case of two colon-separated arguments, the first is a barrier, and the second is a limit.

Arguments are in items, pages or bytes. Note that page size is architecture-specific, it is 4096 bytes on IA32 platform.

You can also specify different suffixes for set parameters (except for the parameters which names start with num). For example, vzctl set VPSID --privvmpages 5M:6M should set privvmpages' barrier to 5 megabytes and its limit to 6 megabytes.

Available suffixes are:
g, G -- gigabytes.
m, M -- megabytes.
k, K -- kilobytes.
p, P -- pages (page is 4096 bytes on x86 architecture, other architectures may differ).

--numproc items[:items]
Maximum number of processes and kernel-level threads. Setting the barrier and the limit to different values does not make practical sense.
--numtcpsock items[:items]
Maximum number of TCP sockets. This parameter limits the number of TCP connections and, thus, the number of clients the server application can handle in parallel. Setting the barrier and the limit to different values does not make practical sense.
--numothersock items[:items]
Maximum number of non-TCP sockets (local sockets, UDP and other types of sockets). Setting the barrier and the limit to different values does not make practical sense.
--vmguarpages pages[:pages]
Memory allocation guarantee. This parameter controls how much memory is available to VPS. The barrier is the amount of memory that VPS's applications are guaranteed to be able to allocate. The meaning of the limit is currently unspecified; it should be set to 2,147,483,647.
--kmemsize bytes[:bytes]
Maximum amount of kernel memory used. This parameter is related to --numproc. Each process consumes certain amount of kernel memory - 16 KB at leas, 30-50 KB typically. Very large processes may consume a bit more. It is important to have a certain safety gap between the barrier and the limit of this parameter: equal barrier and limit may lead to the situation where the kernel will need to kill VPS applications to keep the kmemsize usage under the limit.
--tcpsndbuf bytes[:bytes]
Maximum size of TCP send buffers. Barrier should be not less than 64 KB, and difference between barrier and limit should be equal to or more than value of numtcpsock multiplied by 2.5 KB.
--tcprcvbuf bytes[:bytes]
Maximum size of TCP receive buffers. Barrier should be not less than 64 KB, and difference between barrier and limit should be equal to or more than value of numtcpsock multiplied by 2.5 KB.
--othersockbuf bytes[:bytes]
Maximum size of other (non-TCP) socket send buffers. If VPS processes needs to send very large datagrams, the barrier should be set accordingly. Increased limit is necessary for high performance of communications through local (UNIX-domain) sockets.
--dgramrcvbuf bytes[:bytes]
Maximum size of other (non-TCP) socket receive buffers. If VPS processes needs to send very large datagrams, the barrier should be set accordingly. The difference between the barrier and the limit is not needed.
--oomguarpages pages[:pages]
Guarantees against OOM kill. Under this beancounter the kernel accounts the total amount of memory and swap space used by the VPS processes. The barrier of this parameter is the out-of-memory guarantee. If the oomguarpages usage is below the barrier, processes of this VPS are guaranteed not to be killed in out-of-memory situations. The meaning of limit is currently unspecified; it should be set to 2,147,483,647.
--lockedpages pages[:pages]
Maximum number of pages acquired by mlock(2).
--privvmpages pages[:pages]
Allows controlling the amount of memory allocated by the applications. For shared (mapped as MAP_SHARED) pages, each VPS really using a memory page is charged for the fraction of the page (depending on the number of others using it). For "potentially private" pages (mapped as MAP_PRIVATE), VPS is charged either for a fraction of the size or for the full size if the allocated address space. It the latter case, the physical pages associated with the allocated address space may be in memory, in swap or not physically allocated yet.

The barrier and the limit of this parameter control the upper boundary of the total size of allocated memory. Note that this upper boundary does not guarantee that VPS will be able to allocate that much memory. The primary mechanism to control memory allocation is the --vmguarpages guarantee.

--shmpages pages[:pages]
Maximum IPC SHM segment size. Setting the barrier and the limit to different values does not make practical sense.
--numfile items[:items]
Maximum number of open files. Setting the barrier and the limit to different values does not make practical sense.
--numflock items[:items]
Maximum number of file locks. Safety gap should be between barrier and limit.
--numpty items[:items]
Number of pseudo-terminals (PTY). Note that in OpenVZ each VPS can have not more than 255 PTYs. Setting the barrier and the limit to different values does not make practical sense.
--numsiginfo items[:items]
Number of siginfo structures. Setting the barrier and the limit to different values does not make practical sense.
--dcachesize bytes[:bytes]
Maximum size of filesystem-related caches, such as directory entry and inode caches. Exists as a separate parameter to impose a limit causing file operations to sense memory shortage and return an errno to applications, protecting from memory shortages during critical operations that should not fail. Safety gap should be between barrier and limit.
--numiptent num[:num]
Number of iptables (netfilter) entries. Setting the barrier and the limit to different values does not make practical sense.
--physpages pages[:pages]
This is currently an accounting-only parameter. It shows the usage of RAM by this VPS. Barrier should be set to 0, and limit should be set to 2,147,483,647.
CPU fair scheduler parameters
These parameters control CPU usage by VPS.
--cpuunits num
CPU weight for VPS. Argument is positive non-zero number, which passed to and used in kernel fair scheduler. The larger the number is, the more CPU time this VPS get. Maximum value is 500000, minimal is 8. Number is relative to weights of all the other running VPSs. If cpuunits not specified default value 1000 ia used.

You can set CPU weight for VPS0 (hardware node itself) as well (use vzctl set 0 --cpuunits num).

--cpulimit num
Limit of CPU usage for the VPS, in per cent. Note if the computer has 2 CPUs, it has total of 200% CPU time. Default CPU limit is 0 (no CPU limit).
Iptables control parameters
--iptables name
Restrict access to iptable modules inside VPS (by default all iptables modules that loaded in host system are accessible inside VPS)

You can use the following values for name: iptable_filter, iptable_mangle, ipt_limit, ipt_multiport, ipt_tos, ipt_TOS, ipt_REJECT, ipt_TCPMSS, ipt_tcpmss, ipt_ttl, ipt_LOG, ipt_length, ip_conntrack, ip_conntrack_ftp, ip_conntrack_irc, ipt_conntrack, ipt_state, ipt_helper, iptable_nat, ip_nat_ftp, ip_nat_irc, ipt_REDIRECT.

Network devices control parameters
--netdev_add name
move network device from VPS0 to specified VPS
--netdev_del name
delete network device from specified VPS
Disk quota parameters
--diskspace num[:num]
sets soft and hard disk quotas, in blocks. First parameter is soft quota, second is hard quota. One block is currently equal to 1Kb.
--diskinodes num[:num]
sets soft and hard disk quotas, in i-nodes. First parameter is soft quota, second is hard quota.
--quotatime seconds
sets soft overusage time limit for disk quota (also known as grace period).
--quotaugidlimit num
sets maximum number of user/group IDs in VPS for which disk quota in VPS will be accounted If this value is set to 0, user and group quotas will not be accounted inside VPS.

Note that if you have previously set value of this parameter to 0, changing it while VPS is running will not take effect.

Mount option
--noatime yes|no
Sets noatime flag (do not update inode access times) on file system.
Capability option
--capability capname:on|off
Sets capability inside VPS. Note that setting capability when VPS is running does not take immediate effect; restart VPS in order for changes to take effect. VPS has default set of capability, any operations on capability is logical and with default capability mask.

You can use the following values for capname: chown, dac_override, dac_read_search, fowner, fsetid, kill, setgid, setuid, setpcap, linux_immutable, net_bind_service, net_broadcast, net_admin, net_raw, ipc_lock, ipc_owner, sys_module, sys_rawio, sys_chroot, sys_ptrace, sys_pacct, sys_admin, sys_boot, sys_nice, sys_resource, sys_time, sys_tty_config, mknod, lease, setveid, ve_admin

Device access management
--devnodes device:r|w|rw|none
Give access (r - read, w - write, rw - read write, none - no access) to special file /dev/device from VPS.
Apply config
--applyconfig name
Read VPS parameters from VPS sample configuration file /etc/sysconfig/vz-scripts/ve-name.conf-sample, and apply them, if --save option specified save to VPS config file. These parameters are not changed (HOSTNAME IP_ADDRESS OSTEMPLATE VE_ROOT VE_PRIVATE)

create vpsid --ostemlate name] [--config name] [--private path] [--root path]
Creates VPS area. This operation should be done once, before the first startup of VPS.

If the --config name option is specified, values from example configuration file /etc/sysconfig/vz-scripts/ve-name.conf-sample are put into VPS configuration file. If VPS configuration file already exists, it will be removed.

You can use --root path option to sets the path to the mount point for VPS root directory (default is VE_ROOT specified in vz(5) file). Argument can contain string $VEID, which will be substituted with numeric VPS ID.

You can use --private path option to set the path to directory in which all the files and directories specific to this very VPS are stored (default is VE_PRIVATE specified in vz(5) file). Argument can contain string $VEID, which will be substituted with numeric VPS ID.

destroy
Removes VPS private area by deleting all files, directories and configuration file of this VPS.
start
Mounts (if necessary) and starts VPS.
stop
Stops and unmounts VPS.
restart
Restart VPS, stop if running and start.
status
Shows VPS status. Basically this is a line with five words separated by spaces. First word is literally VPS. Second word is VPS ID. Third word is showing whether VPS exists or not, it can be either exist or deleted. Fourth word is showing the status of VPS filesystem, it can be either mounted or unmounted. Fifth word shows if VPS is running, it can be either running or down.

This command can also be usable from scripts.

mount
Mounts VPS private area.
umount
Unmounts VPS private area. Note that stop does umount automatically.
exec vpsid command
Executes command in VPS. Environment variables are not set inside VPS. Signal handlers may differ from default settings. If command is -, commands are read from stdin.
exec2 vpsid command
The same as exec, but return code is that of command.
runscript
Run specified shell script in VPS, if VPS is not runnning it will be started.
enter
Enters into VPS. This option is a back-door for host root only.

--help
Prints help message with a brief list of possible options.
--version
Prints vzctl version.

Returns 0 upon success.

To create and start "basic" VPS with ID 1000 using fedora-3 ostemplate, and IP address 192.168.10.200:
vzctl create 1000 --ostemplate fedora-3 --config vps.basic
vzctl set 1000 --ipadd 192.168.10.200 --save
vzctl start 1000
To set number of processes barrier/limit to 80/100 processes and PTY barrier/limit to 16/20 PTYs:
vzctl set 1000 --numproc 80:100 -t 16:20 --save

To execute command ls -la in this VPS:
vzctl exec 1000 /bin/ls -la

To execute command pipe ls -l / | sort in this VPS:
vzctl exec 1000 'ls -l / | sort'

To stop this VPS:
vzctl stop 1000

To permanently remove this VPS:
vzctl destroy 1000

/etc/sysconfig/vz
/etc/sysconfig/vz-scripts/vpsid.conf
/proc/vz/veinfo
/proc/vz/vzquota
/proc/user_beancounters
/proc/fairsched

vz(5), vps.conf(5), vzquota(8),

Copyright (C) 2000-2005, SWsoft. Licensed under QPL.
10 Aug 2005 OpenVZ