Time Management

What is Time Management?

Time Management: Manages the Cloud system time and allows you to configure time servers for the Cloud. After you configure NTP time servers for the Cloud, the clock of the time servers is synced with all nodes of the Cloud.

Concepts

Time management involves the following concepts：

Internal time server: Uses a management mode or host as an NTP time server of the Cloud system time so the other nodes of the Cloud may sync time with the time server.
External time server: Uses a node that does not belong to the Cloud as an NTP time server, which directly syncs time with all nodes of the Cloud or syncs time with the Cloud nodes via the internal time server.
Time sync: The process in which the time of a node on the Cloud is synced with a time server.

Fundamentals

The time sync of the nodes on the Cloud with a time server is achieved mainly via network time protocol (NTP) and related algorithms. The following lists the sync process:

You configure an internal or external time server for time sync.
The nodes on the Cloud connect to the time server to obtain its timestamp information.
Based on the timestamp, the nodes on the Cloud calculate their time difference with the time server.
Based on their respective time difference, the nodes on the Cloud alter their local time to achieve time sync.
The nodes on the Cloud implement process 2 to 4 regularly for sustained time sync.

The Cloud supports the following three time protocol modes:

Internal: Uses a management mode or host as an NTP time server of the Cloud system time so the other nodes of the Cloud may sync time with the time server. You can add up to 2 internal time servers for the Cloud.
Internal and External: Uses a node that does not belong to the Cloud as an NTP time server and uses a management mode or host as an NTP time server of the Cloud system time. The external time server syncs time with the internal time server first and then the internal time server syncs time with the other nodes of the Cloud. You can add up to 2 internal time servers and 2 external time servers for the Cloud.
External: Uses a node that does not belong to the Cloud as an NTP time server, which syncs time with all nodes of the Cloud. You can add up to 2 external time servers for the Cloud.

Benefits

Time management has the following benefits:

Accurate: The time clock adjustment algorithm used ensures an accurate time sync.
Automatic: The time sync mechanism is auto implemented regularly. Manual interference is not required.
Reliable: You can configure multiple time servers to ensure the reliability and stability of the time sync mechanism.
Intuitive: Time server configuration and its relationship with the Cloud time are displayed in a topology. In addition, the current Cloud time and the time zone are displayed.

Scenarios

Time management applies to the following scenarios:

Network management: The logs collected from different network devices require accurate time records for efficient troubleshooting. The time sync mechanism provided can well satisfy this demand.
Billing: Time management can ensure consistent and accurate time records for billing systems so that the billing info is correct.
Collaboration: Time management can ensure unified time for multiple systems so that they can well collaborate with each other based on the preconfigured execution time sequence when handling a complex task.

Manage Time Server

On the main menu of ZStack Cloud, choose Settings > System Setting > Time Management. Then, the Time Management page is displayed.

The following table lists the actions that time management supports:

Action	Description
Modify NTP Time Server	Modify NTP time servers. The following three modes are supported: Internal: Uses a management mode or host as an NTP time server of the Cloud system time so the other nodes of the Cloud may sync time with the time server. Internal and External: Uses a node that does not belong to the Cloud as an NTP time server and uses a management mode or host as an NTP time server of the Cloud system time. The external time server syncs time with the internal time server first and then the internal time server syncs time with the other nodes of the Cloud. External: Uses a node that does not belong to the Cloud as an NTP time server, which syncs time with all nodes of the Cloud. You can add up to 2 external time servers for the Cloud. Note: You can add up to 2 internal time servers and 2 external time servers for the Cloud. You can enter an IP address or domain name of an external time server. Before you modify a time server, make sure that the management node is in Connected status. Modifying an NTP time server may cause the time of the nodes on the Cloud inconsistent with each other and monitoring data errored or corrupted, and may affect operating tasks. Proceed with caution.
Forced Sync Time by Force	If the system time has relatively large difference with the time of the NTP time server, The auto time consistency adjustment may take a while. You can implement forced time sync to eliminate the time difference in a short time.

Action

Description

Modify NTP Time Server

Modify NTP time servers. The following three modes are supported:

Internal: Uses a management mode or host as an NTP time server of the Cloud system time so the other nodes of the Cloud may sync time with the time server.
Internal and External: Uses a node that does not belong to the Cloud as an NTP time server and uses a management mode or host as an NTP time server of the Cloud system time. The external time server syncs time with the internal time server first and then the internal time server syncs time with the other nodes of the Cloud.
External: Uses a node that does not belong to the Cloud as an NTP time server, which syncs time with all nodes of the Cloud. You can add up to 2 external time servers for the Cloud.

Note:

You can add up to 2 internal time servers and 2 external time servers for the Cloud. You can enter an IP address or domain name of an external time server.
Before you modify a time server, make sure that the management node is in Connected status.
Modifying an NTP time server may cause the time of the nodes on the Cloud inconsistent with each other and monitoring data errored or corrupted, and may affect operating tasks. Proceed with caution.

Forced Sync Time by Force

If the system time has relatively large difference with the time of the NTP time server, The auto time consistency adjustment may take a while. You can implement forced time sync to eliminate the time difference in a short time.

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