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vzctl

NAME

vzctl - utility to control a Virtual Environment.

SYNOPSIS

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

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

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

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

vzctl runscript veid script

vzctl --help | --version

DESCRIPTION

Utility vzctl runs on Hardware Node (HN) and performs direct manipulations with Virtual Environments (VEs).

Virtual Environments can be referred to by either numeric veid or by name (see --name option). Note that VE ID <= 100 are reserved for OpenVZ internal purposes.

OPTIONS

Flags

These flags can be used with almost any option.

--quiet

Disables logging to log file and screen.

--verbose

Sets logging level to maximum value.

Setting VE parameters

set veid [parameters] [--save]

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

The following options can be used with set command.

Miscellaneous parameters

--onboot yes|no

Sets whether this VE will be started during system boot up. VE 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 VE. This is essentially a mount point for VE root. Value must contain string $VEID, which will be substituted with numeric VE ID. Changing this parameter is not recommended, better edit vz(5) global configuration file.

--userpasswd user:password

Sets password for the given user in VE, 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 VE (by modifying its /etc/passwd and /etc/shadow files).

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

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

--disabled yes|no

Disable VE start. To force the start of a disabled VE, use vzctl start with --force option.

--name name

Add a name for a VE. The name can later be used in subsequent calls to vzctl in place of veid.

--setmode restart|ignore

Whether to restart a VE after applying any parameters requiring that the VE be restarted for those to take effect.

Network related parameters

--ipadd addr

Adds IP address to a given VE. Note that this option is incremental, so addr are added to already existing ones.

--ipdel addr | all

Removes IP address addr from a VE. If you want to remove all addresses, use --ipdel all.

--hostname name

Sets VE hostname. vzctl writes it to the appropriate file inside a VE (distribution-dependent).

--nameserver addr

Sets DNS server IP address for a VE. 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 a VE. 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.

--netif_add ifname[,mac,host_ifname,host_mac]

Adds a virtual ethernet device (veth) to a given VE. Here ifname is the ethernet device name in the VE, mac is its MAC address, host_ifname is the ethernet device name on the host, and host_mac is its MAC address. MAC addresses should be in the format like XX:XX:XX:XX:XX:XX. All parameters except ifname are optional and are automatically generated if not specified.

Interface configuration

The following options can be used to reconfigure the already-created virtual ethernet interface. To select the interface to configure, use --ifname name option.

 --mac XX:XX:XX:XX:XX:XX - MAC address of interface inside VE.
 --host_ifname name - interface name for virtual interface in VE0.
 --host_mac XX:XX:XX:XX:XX:XX - MAC address of interface in VE0.

--netif_del dev_name|all

Removes virtual ethernet device from VE. If you want to remove all devices, use all.

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. Each argument is either a number, a number with a suffix, or a special value unlimited.

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 veid --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).

You can also specify the literal word unlimited in place of a number. In that case the corresponding value will be set to LONG_MAX, i. e. the maximum possible value.

--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 a VE. The barrier is the amount of memory that VE's applications are guaranteed to be able to allocate. The meaning of the limit is currently unspecified; it should be set to unlimited.

--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 VE 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 VE 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 VE 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 VE processes. The barrier of this parameter is the out-of-memory guarantee. If the oomguarpages usage is below the barrier, processes of this VE are guaranteed not to be killed in out-of-memory situations. The meaning of limit is currently unspecified; it should be set to unlimited.

--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 VE 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), VE 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 VE 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 VE 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 VE. Barrier should be set to 0, and limit should be set to unlimited.

CPU fair scheduler parameters

These parameters control CPU usage by VE.

--cpuunits num

CPU weight for a VE. 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 VE get. Maximum value is 500000, minimal is 8. Number is relative to weights of all the other running VEs. If cpuunits not specified default value 1000 ia used.

You can set CPU weight for VE0 (hardware node itself) as well (use vzctl set 0 --cpuunits num). Usually, OpenVZ initscript (/etc/init.d/vz) takes care of setting this.

--cpulimit num[%]

Limit of CPU usage for the VE, 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). --cpus num sets number of CPUs available in the VE.

Memory output parameters

This parameter control output of /proc/meminfo inside a VE

--meminfo none

No /proc/meminfo virtualization (the same as on host system).

--meminfo mode:value

Configure total memory output in a VE. Free memory is evaluated accordingly to the mode being set.
You can use the following modes for mode:
pages:value - sets total memory in pages
privvmpages:value - sets total memory as privvmpages * value

Default is privvmpages:1.

Iptables control parameters

--iptables name

Restrict access to iptables modules inside a VE (by default all iptables modules that are loaded in the host system are accessible inside a VE).

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, xt_mac, ipt_owner.

Network devices control parameters

--netdev_add name

move network device from VE0 to a specified VE

--netdev_del name

delete network device from a specified VE

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. Also suffixes G, M, K can be specified (see Resource limits section for more info).

--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 a VE for which disk quota inside the VE will be accounted. If this value is set to 0, user and group quotas will not be accounted inside the VE.

Note that if you have previously set value of this parameter to 0, changing it while the VE 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 a VE. Note that setting capability when the VE is running does not take immediate effect; restart VE in order for changes to take effect. Note a VE has default set of capabilities, thus any operation on capabilities is "logical and" with the 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.

WARNING: setting some of those capabilities may have far reaching security implications, so do not do it unless you know what you are doing. Also note that setting setpcap:on for a VE will most probably lead to inability to start it.

Device access management

--devnodes device:r|w|rw|none

Give the VE an access (r - read, w - write, rw - read write, none - no access) to a device designated by the special file /dev/device. Device file is created in VE by vzctl.

--devices b|c:major:minor|all:[r|w|rw|none]

Give the VE an access to a block or character device designated by its major and minor numbers. Device file have to be created manually.

Features management

--features name:on|off

Enable or disable a specific VE feature. Known features are: sysfs, nfs.

Apply config

--applyconfig name

Read VE parameters from the VE sample configuration file /etc/vz/conf/ve-name.conf-sample, and apply them, if --save option specified save to the VE config file. The following parameters are not changed: HOSTNAME, IP_ADDRESS, OSTEMPLATE, VE_ROOT, and VE_PRIVATE.

--applyconfig_map name

Apply VE config parameters selected by name group, now only name argument supported. Restore VE name based on NAME variable in VE configuration file.

I/O priority management

--ioprio priority

Assigns I/O priority to VE. Priority range is 0-7. The greater priority is, the more time for I/O activity VE has. By default each VE has priority of 4.

Checkpointing and restore

Checkpointing is a feature of OpenVZ kernel which allows to save a complete state of a running VE, and to restore it later.

chkpnt veid [--dumpfile name]

This command saves a complete state of a running VE to a dump file, and stops the VE. If an option --dumpfile is not set, default dump file name /vz/dump/Dump.veid is used.

restore veid [--dumpfile name]

This command restores a VE from dump file created by the chkpnt command.

Performing VE actions

create veid [--ostemplate name] [--config name] [--private path] [--root path] [--ipadd addr] [--hostname name]

Creates a new VE area. This operation should be done once, before the first start of the VE.

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

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

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

You can use --ipadd addr option to assign an IP address to a VE. Note that this option can be used multiple times.

You can use --hostname name option to set a host name for a VE.

destroy

Removes a VE private area by deleting all files, directories and configuration file of this VE.

start [--wait] [--force]

Mounts (if necessary) and starts a VE. Unless --wait option is specified, vzctl will return immediately; otherwise an attempt to wait till the default runlevel is reached will be made by vzctl.

Specify --force if you want to start a VE which is disabled (see --disabled).

stop

Stops and unmounts a VE.

restart

Restarts a VE, i.e. stops it if it is running, and starts again.

status

Shows a VE status. Basically this is a line with five words separated by spaces. First word is literally VEID. Second word is the numeric VE ID. Third word is showing whether this VE exists or not, it can be either exist or deleted. Fourth word is showing the status of the VE filesystem, it can be either mounted or unmounted. Fifth word shows if the VE is running, it can be either running or down.

This command can also be usable from scripts.

mount

Mounts VE private area.

umount

Unmounts VE private area. Note that stop does umount automatically.

exec veid command

Executes command in a VE. Environment variables are not set inside the VE. Signal handlers may differ from default settings. If command is -, commands are read from stdin.

exec2 veid command

The same as exec, but return code is that of command.

runscript

Run specified shell script in a VE, if the VE is not runnning it will be started.

enter

Enters into a VE. This option is a back-door for host root only.

Other options

--help

Prints help message with a brief list of possible options.

--version

Prints vzctl version.

DIAGNOSTICS

Returns 0 upon success.

EXAMPLES

To create and start "basic" VE with ID of 1000, using fedora-core-5 OS template, and IP address of 192.168.10.200:
       vzctl create 1000 --ostemplate fedora-core-5 --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, 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 VE:
       vzctl exec 1000 /bin/ls -la

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

To stop this VE:
       vzctl stop 1000

To permanently remove this VE:
       vzctl destroy 1000

FILES

/etc/vz/vz.conf
/etc/vz/conf/veid.conf
/proc/vz/veinfo
/proc/vz/vzquota
/proc/user_beancounters
/proc/fairsched

SEE ALSO

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

LICENSE

Copyright (C) 2000-2007, SWsoft. Licensed under GNU GPL v2.