Considerations

Overview

ZStack provides high availability (HA) for multiple management nodes (MNs, also known as hosts) by using separate HA suites. When any one of the MNs is disconnected, the HA will be triggered in seconds to ensure the business continuity.

HA mechanism: In a multi-MN model, each MN runs a zsha2 HA process. This process monitors the key services, including the MN service, UI service, and database service, in each MN in real time. When any key service is down, the system immediately triggers virtual IP (VIP) migration through Keepalived, and then attempts to restore the downtime service.

This topic provides an example of a dual-MN HA scenario to describe the procedures for installation, deployment, and upgrade. This topic also provides some considerations for using multi-MN HA. For more information, see the Multi-MN HA Tutorial.

Installation and Deployment

• Assume that you have a single-MN environment and want to upgrade it to a dual-MN HA environment.
  1. Download the latest ZStack Custom ISO, bin package, and multi-MN HA suite from the official website.
  2. Upgrade your existing MN to the latest version of ZStack.
  3. Install the latest version of ZStack in the newly added MN.
  4. Install a license for the newly added MN. Make sure that the license type of these two MNs is exactly the same.
  5. Import the HA suite into the previous MN. Then, decompress and install the suite.
• Assume that you have a newly installed dual-MN environment and want to deploy it as an HA environment.
  1. Download the latest ZStack Custom ISO, bin package, and multi-MN HA suite from the official website.
  2. Install the latest version of ZStack in these two MNs.
  3. Install a license for these two MNs. Make sure that the license type of these two MNs is exactly the same.
  4. Import the HA suite into one of the MNs. Then, decompress and install the suite.

Upgrade

• HA suite upgrade

  After you obtain the new version of the HA suite, you can use it to upgrade the current zsha2 service.

  After the databases of the active and standby MNs are automatically synchronized, import the new version of the HA suite into the active MN and decompress the suite. Then, run the following command in the active MN to finish the HA suite upgrade:

  [root@localhost ~]# ./zsha2 upgrade-ha

• MN upgrade

  In the dual-MN HA scenario, you need to upgrade the HA suite before you can upgrade a MN.

  You only need to run the following commands in one MN. Then, both MNs can be upgraded.

  • If you perform upgrade from the bin package, run the following command:

    [root@localhost ~]# zsha2 upgrade-mn -peerpass password ./ZStack-installer-3.10.0.bin

  • If you perform upgrade from ISO, run the following command:

    [root@localhost ~]# zsha2 upgrade-mn -peerpass password ./ZStack-x86_64-DVD-3.10.0-c76.iso

    Note: In the command above, the -peerpass parameter is optional. You can set a password for SSH login to the peer MN.

Considerations

• We recommend that you configure at least 8 CPUs and 12 GB memory for the host (MN).
• We recommend that you use a 10-Gigabit bandwidth or above for the management network. If the management network is deployed independently, a 1-Gigabit bandwidth is allowed.
• We recommend that you use zs-network-setting to create static network bridges as needed.
• The multi-MN HA suite depends on ZStack 2.6.0 and later versions. Note that the version of the HA suite and ZStack must be the same. For example, if the version of the HA suite is 2.6.0, the version of ZStack must also be 2.6.0.
• The ZStack version of these two MNs must be the same. In addition, the license type of these two MNs must also be the same.
• To install an HA suite, you need to put zsha2 and zstack-hamon to the same directory. During the installation, zsha2 will automatically deploy zstack-hamon and related configuration files.
• During the installation, the database of the standby MN will be overwritten by the database of the active MN. Please exercise caution.
• To ensure real-time synchronization of monitoring data between these two MNs, we recommend that you perform password-free SSH login between these two MNs.
• The version of the Chrome browser used to access the MN must be 49 or later.