How To Move VMS to a Different CNode

  • Updated on Jan 24, 2026
  • 4 minute(s) read
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Summary

The VAST Management Service runs in a dedicated Docker container on a single CNode in the VAST Cluster.  By default, it can run on any enabled CNode.  In some cases, it may become desirable or necessary to move VMS.   There are two ways to move the VMS instance to a new CNode.

Prerequisites

  1. Determine which node VMS is running on

    • From the UI, go to Infrastructure -> cnodes

    • The VMS column will indicate which CNode currently has VMS:

The image displays an Infrastructure panel in a management interface, focusing on Cnodes listed with various details such as IP address, OS version, BMC build, and VMS status. The highlighted 'VMS' column indicates whether Virtual Machines Service is enabled or not, crucial for system monitoring and configuration.

VMS will indicate current CNode

  • From the CLI run the command clush -g cnodes docker ps | grep vms.  This will return an IP address from the CNode that has VMS:

vastdata@cnode-3-13 ~:$ clush -g cnodes docker ps | grep vms
172.16.3.11: 95a5407f6efb vastdata.registry.local:5000/dev/orion:release-4.2.0-sp-active-606303-vms "/usr/bin/dumb-init …" 19 minutes ago Up 19 minutes vast_vms

Moving VMS

Deactivate the CNode

The easiest way to move VMS is to deactivate the CNode on which it is running, thereby forcing it to move.  You can then re-activate the CNode once VMS has moved.  To do this, simply click on the three dots under the Actions column on the same page as above, and click on Deactivate

In this Infrastructure dashboard, administrators can manage various CNodes listed under their respective details such as Name, Hostname, Management IP, Operating System (OS), BMC version, and more. The Actions dropdown provides options like Activate or Deactivate nodes, among others, allowing users to control node statuses dynamically. --- The image depicts an Infrastructure management interface where users can oversee and manipulate CNodes through detailed parameters including names, hostnames, management IPs, OS versions, BMCs, states, and enabling/disabling actions via the 'Actions' menu.

Deactivate the current CNode where VMS is running

Moving VMS without deactivating the CNode - Using VIP

Beginning with VAST version 4.2, it is possible to indicate a VMS preferred status in a VIP pool.  In order to move VMS without deactivating a CNode, you can temporarily create a dummy VIP pool with all the CNodes and then disable the CNode it is currently on.

  1. Go to Network Access -> VIP Pools in the UI

In the network configuration interface, under the "Infrastructure" section and within the "Network Access" category, there users can manage virtual IP pools to allocate dynamic IP addresses for their network elements.

Virtual IP Pools

  1. Click on "Create VIP Pool"

The image shows the "Network Access" section in a configuration interface with tabs for Virtual IP Pools, Virtual IPs, and DNS management. The "Create New VIP pool" button is highlighted by an arrow, indicating where users can create new virtual IP pools.

Create VIP Pool

 

  1. In the Add Virtual IP Pool window, use a dummy IP range, ensure all of your CNodes are in the pool, and toggle VMS Preferred on.

The image shows a configuration interface for updating a VIP pool, with fields to specify the name, subnet CIDR, CNodes included in the pool (cnode-3-11, cnode-2-12, cnoade-313), and an IP range from 192.168.50.54 to 182.58.

toggle VMS Preferred

 

  1. Click Update.  This will activate the VIP Pool

  2. Now edit that VIP Pool by clicking the three dots under the Actions column to reopen the same window.

The image displays an interface element where users can select their preference for using Virtual Machines (VMS) and edit or remove their choice through the options provided in the drop-down menu below 'Actions'.

Edit VIP Pool

  1. Uncheck the CNode that currently has VMS (found in the prerequisite section)

The screenshot displays a dropdown list titled "CNodes," listing nodes labeled as cnode-3-11, cnode3- 12, and cnode_3- -13, with "cnode- 3-ll" highlighted in red to indicate selection or.

Uncheck the current CNode

 

  1. Click Update at the bottom of the Update Vip Pool page.  VMS will then move to a new CNode.

  2. The VIP Pool can then be deleted using the three-dot menu under Actions and selecting Remove

The image displays an interface option with options for selecting 'VMS preferred'. The red arrows point to an "Edit" and "Remove" button, indicating functionalities available in this section for modifying or deleting selections within the VMS configuration.

Remove VIP pool

Moving VMS without deactivating the CNode - Using VMS Settings

  1. Connect via vCLI with the admin user

  2. Execute vms list and check which node is the VMS

    vcli: admin> vms list
+------+---------------------+------------+--------------------------------+---------------------+------------+-----------+----------------+-------------+---------------------+------------------+--------------+-----------------------+------------------------+---------------+----------------------------+
| Name | Created             | SW-Version | Build                          | Auto-Logout-Timeout | IP1        | IP2       | MGMT-VIP       | Mgmt-CNode  | Performance-base-10 | Capacity-base-10 | Login-banner | Access-token-lifetime | Refresh-token-lifetime | MGMT-VIP-IPv6 | Perf-debug-metrics-enabled |
+------+---------------------+------------+--------------------------------+---------------------+------------+-----------+----------------+-------------+---------------------+------------------+--------------+-----------------------+------------------------+---------------+----------------------------+
| VMS  | 2024-12-12 17:04:29 | 5.1.0.200  | release-5-1-0-sp45-1560629-vms | 600                 | 10.10.64.1 | 10.10.0.1 | 10.141.200.132 | cnode-128-1 | True                | True             | None         | 01:00:00              | 1 00:00:00             | UNKNOWN       | N/A                        |
+------+---------------------+------------+--------------------------------+---------------------+------------+-----------+----------------+-------------+---------------------+------------------+--------------+-----------------------+------------------------+---------------+----------------------------+

    1. Mgmt-CNode is cnode-128-1

  3. Run the following command to change the VMS to a different node 

    vms modify --preferred-cnode-ids 2

  4. Check after a few minutes that VMS moved to cnode ID 2

    vcli: admin> vms list
+------+---------------------+------------+--------------------------------+---------------------+------------+-----------+----------------+-------------+---------------------+------------------+--------------+-----------------------+------------------------+---------------+----------------------------+
| Name | Created             | SW-Version | Build                          | Auto-Logout-Timeout | IP1        | IP2       | MGMT-VIP       | Mgmt-CNode  | Performance-base-10 | Capacity-base-10 | Login-banner | Access-token-lifetime | Refresh-token-lifetime | MGMT-VIP-IPv6 | Perf-debug-metrics-enabled |
+------+---------------------+------------+--------------------------------+---------------------+------------+-----------+----------------+-------------+---------------------+------------------+--------------+-----------------------+------------------------+---------------+----------------------------+
| VMS  | 2024-12-12 17:04:29 | 5.1.0.200  | release-5-1-0-sp45-1560629-vms | 600                 | 10.10.64.2 | 10.10.0.2 | 10.141.200.132 | cnode-128-2 | True                | True             | None         | 01:00:00              | 1 00:00:00             | UNKNOWN       | N/A                        |
+------+---------------------+------------+--------------------------------+---------------------+------------+-----------+----------------+-------------+---------------------+------------------+--------------+-----------------------+------------------------+---------------+----------------------------+

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