Time synchronization troubleshooting

VMmanager platform uses a built-in time synchronization service for proper cluster operation. For more details, see the article Time synchronization.

The time synchronization service operates automatically, but in some cases, issues may arise that prevent it from functioning correctly. This article describes typical scenarios and their solutions.

Basic time synchronization service check on a node

If a node fails to join the cluster or the platform reports time synchronization problems, perform the following checks:

Connect to the cluster node via SSH. For more information about connecting via SSH, see Workstation setup.
Check which time synchronization services are installed:
Astra Linux
```
sudo apt policy chrony
sudo apt policy ntp
```
Alma Linux
```
sudo rpm -q chrony
sudo rpm -q ntp
```
The same synchronization service must be used on the platform server and all cluster nodes. For example, if the platform server uses chrony, the nodes must also use it.
Note
Astra Linux uses ntp by default. However, for correct time synchronization in heterogeneous environments where a platform on Astra Linux interacts with nodes on AlmaLinux, it is recommended to use chrony instead of the default service.
If both packages are installed, remove ntp:
Important!
Before removing any package, ensure the alternative time synchronization service is correctly configured and running.
AlmaLinux
```
sudo dnf remove ntp
```
Astra Linux
```
sudo apt remove ntp
```

Check the status of the ntp or chrony service:

sudo systemctl status ntp

sudo systemctl status chronyd

Check the configuration of the ntp or chrony service:
```
cat /etc/ntp.conf
```
```
cat /etc/chrony/chrony.conf
```
Ensure the configuration file specifies correct time servers. For more details, see the article Time synchronization.
Check the overall system time status:
```
timedatectl
```
Expected result: The line System clock synchronized should have the value yes.
For the chrony service only, additionally check:
- synchronization accuracy:
```
chronyc tracking
```
  Expected result: The value of the Last offset parameter should be small, e.g., less than a few milliseconds.
  Example output
```
Stratum         : 3
Ref time (UTC)  : Tue Nov 18 09:42:49 2025
System time     : 0.000004589 seconds slow of NTP time
Last offset     : -0.000031991 seconds
```
- current synchronization sources:
```
chronyc sources -v
```
  Expected result: There should be sources with the state ^* or ^+. Sources with ^? indicate a loss of connection.

Tasks fail on nodes

Problem

Time synchronization settings are applied, tasks appear on the nodes, but they fail almost immediately.

Solution

To find the cause of the problem:

Connect to the server with the platform via SSH. For more information about connecting via SSH, see Workstation setup.
Switch to the vm_box container:
```
docker exec -it vm_box sh
```
Check the following logs from the time the setting was applied:
- /var/log/vm_writer.log;
- /var/log/vmctl.log.

For more details on working with logs, see the article Platform log files.

Setting is not applied on the platform

Problem

After attempting to apply the time synchronization setting, tasks are not created on the nodes.

Solution

To find the cause of the problem:

Connect to the server with the platform via SSH. For more information about connecting via SSH, see Workstation setup.
Switch to the vm_box container:
```
docker exec -it vm_box sh
```
Check the following logs from the time the setting was applied:
- /var/log/vm_writer.log;
- Installer logs, e.g., /var/log/vm-install.log.

The logs will indicate the specific error preventing the platform from initiating the synchronization process.

For more details on working with logs, see the article Platform log files.

Node is synchronized, but "Time is not synchronized" error persists

Problem

After connecting a new node, all tasks are completed successfully, checks on the node show correct synchronization, but the platform still displays the Time is not synchronized warning.

Solution

This is expected behavior. Synchronization monitoring runs on a schedule once per hour and may have saved the node's state before it was synchronized. To resolve, do one of the following:

wait for about an hour. The warning should disappear automatically after the next monitoring run;
restart the monitoring service on the platform server:
```
docker restart nodewarden
```

Node was in maintenance mode and its time is desynchronized

Problem

Time settings were changed while the node was disabled. After re-adding it to the cluster, its time is not synchronized.

Solution

To resolve the issue:

Go to Settings in the right sidebar menu → Global Settings section → Time block.
On the warning banner Time is not synchronized on N node, click the Apply settings button.

This will initiate the synchronization process on all nodes, including the recently re-added one.

Useful tips