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vzmigrate

This command is used for moving Containers to another system with minimal downtime. It has the following syntax:

vzmigrate [options] Destination_Node {Container_list}

{CT_list} is a list of <CT_ID>[:<new_CT_ID>] pairs. A new Container ID parameter is needed in case both the Source Node (the one where you run the vzmigrate command) and the Destination Node have a Container with the ID of <CT_ID>. You can specify multiple Containers at once for migration.

The following options can be used with vzmigrate:

-s, --nostart

Do not attempt to start the Container on the Destination Hardware Node after its successful migration if the Container was running on the Source Hardware Node prior to the migration. This option does not have any effect if the Container was not running on the Source Hardware Node.

-r, --remove-area yes|no

This option takes precedence of the REMOVEMIGRATED setting from the global configuration file. If "yes" is specified, then the Container private area and configuration file will be deleted after successful migration. If "no" is specified, the private area and configuration file will be left on the Source Node and have the .migrated suffix appended to them.

-f, --nodeps
[=[all][,cpu_check]
[,disk_space]
[,technologies]
[,license][,rate]]

During its execution, vzmigrate performs a number of checks on the Destination Node (e.g. it verifies that all OS and application templates required for the Container are present on the Destination Node) and if some checks fail, exits with an error. This option allows you to bypass all checks and migrate the Container. If you specify this option for a running Container, the Container will not be automatically started on the Destination Node. You should manually start it after adding the missing templates.

You can additionally use one or several of the following parameters with this option:

  • all: do not perform any checks on the Destination Node;
  • cpu_check: do not check the CPU capabilities of the Destination Node;
  • disk_space: do not check the amount of disk space on the Destination Node;
  • technologies: do not check a set of technologies provided by the Virtuozzo kernel on the Destination Node (please see the description of the TECHNOLOGIES parameter in the Container Configuration File subsection for details);
  • license: do not check the license installed on the Destination Node;
  • rate: do not check the value of the RATE parameter in the Virtuozzo global file.

-b, --batch

Normally you do not have to specify this option. It is used by Virtuozzo scripts and changes the screen output to a computer-parsable form.

--ssh=<ssh_options>

Additional options to be passed to ssh while connecting to the Destination Node.

Note: Please do not specify the Destination Node hostname as an option of --ssh.

--keeper[=CT_ID]

The Container used to keep identification information on the migrated Container (e.g. information on Container IP addresses). If this option is omitted, the Service Container on the Source Node is used for this purpose.

--keep-dst

Do not remove the 'synched' Container private area on the Destination Node if some error occurred during the migration. This option allows you to prevent vzmigrate from the repeated 'synching' the Container private area if the first migration attempt failed for some reason or other.

--online

Migrates the running Container with zero downtime. By default, the 'iterative online migration' type is used. During the migration:

  • the main amount of Container memory is transferred to the Destination Node;
  • the Container is 'dumped' and saved to an image file;
  • the image file is transferred to the Destination Node where it is 'undumped'.

Using this type of online migration allows you to attain the smallest service delay.

To not use the 'iterative online migration' type, supply the --noiter option.

Note: Detailed information on zero-downtime migration types is provided in the Parallels Virtuozzo Container User's Guide.

--lazy

Can be used only together with the --online option. Speeds up the zero downtime migration process if your Container is running a number of memory-consuming applications. This option allows you to decrease the size of the image file storing all Container private data and transferred to the Destination Node by leaving the main amount of memory in a locked state on the Source Node and swapping this memory from the Source Node on demand.

While using the --lazy option, please turn your attention to the following:

  • The migration type is set to "lazy" only if you additionally supply the --noiter option.
  • If the --noiter option is not supplied, the migration type is set to 'lazy + iterative'.

--noiter

Can be used only together with the --online option. Sets the migration type to 'simple'. This option cannot be used together with the --require-realtime option.

--require-realtime

Can be used only together with the --online option. Forces vzmigrate to move the Container by using the 'iterative online migration' type. If this migration type cannot be carried out for some reason or another, the command will fail and exit. This option cannot be used together with the --noiter option.

If the default 'iterative online migration' type cannot be carried out, and this option is omitted , vzmigrate will try to move your Container by making use of other types: the 'simple online migration' type or the 'lazy online migration' type (depending on the presence of the --lazy option).

--readonly

Just copy the specified Container to the Destination Node without making any changes to the Container on the Source Node.

--dry-run

Simulate the same operations as vzmigrate completes without specifying this option (connects to the Destination Node, verifies that all OS and application templates required for the Container are present on the Node, etc.); however, the Container itself is not moved to the Destination Node.

Note: Containers created under the Virtuozzo Containers 32-bit version can be migrated to Hardware Nodes running the Virtuozzo Containers 64-bit version for the x86-64 processors and cannot be moved to Hardware Nodes running the Virtuozzo Containers 64-bit version for the IA-64 processors. Moreover, you can migrate Containers created under the corresponding Virtuozzo Containers 64-bit version to Nodes running the same Virtuozzo Containers version for 64-bit processors.

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