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ONTAP MetroCluster

Prepare to install the ONTAP Mediator service

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Your environment must meet certain requirements.

The following requirements apply to one disaster recovery group (DR group). Learn more about DR groups.

  • If you plan on updating your Linux version, do so before you install the most current ONTAP Mediator service.

  • The ONTAP Mediator service and MetroCluster Tiebreaker software should not both be used with the same MetroCluster configuration.

  • The ONTAP Mediator must be installed on a LINUX host at a separate location from the MetroCluster sites.

    The connectivity between the ONTAP Mediator and each site must be two separate failure domains.

  • The ONTAP Mediator service can support up to five MetroCluster configurations simultaneously.

  • Automatic unplanned switchover is supported in ONTAP 9.7 and later.

Network requirements for using Mediator in a MetroCluster configuration

To install the ONTAP Mediator service in a MetroCluster configuration, you must make sure that the configuration meets several network requirements.

  • Latency

    Maximum latency of less than 75ms (RTT).

    Jitter must be no more than 5ms.

  • MTU

    The MTU size must be at least 1400.

  • Packet loss

    For both Internet Control Message Protocol (ICMP) and TCP traffic, packet loss must be less than 0.01%.

  • Bandwidth

    The link between the Mediator service and one DR group must have at least 20Mbps of bandwidth.

  • Independent connectivity

    Independent connectivity between each site and the ONTAP Mediator is required. A failure in one site must not interrupt the IP connectivity between the other two unaffected sites.

Host requirements for the ONTAP Mediator in a MetroCluster configuration

You must ensure that the configuration meets several host requirements.

  • ONTAP Mediator must be installed at an external site that is physically separated from the two ONTAP clusters.

  • ONTAP Mediator supports a maximum number of five MetroCluster configurations.

  • ONTAP Mediator does not require more than the host operating system's minimum requirements for CPU and memory (RAM).

  • In addition to the host operating system's minimum requirements, at least 30GB of additional usable disk space must be available.

    • Each DR group requires up to 200MB of disk space.

Firewall requirements for ONTAP Mediator

ONTAP Mediator uses a number of ports to communicate with specific services.

If you are using a third-party firewall:

  • HTTPS access must be enabled.

  • It must be configured to allow access on ports 31784 and 3260.

    When using the default Red Hat or CentOS firewall, the firewall is automatically configured during Mediator installation.

The following table lists the ports that you must allow in your firewall:

Note The iSCSI port is only required in a MetroCluster IP configuration.






ONTAP cluster management interfaces

ONTAP Mediator web server



ONTAP cluster (data LIF or data management LIF)

ONTAP Mediator iSCSI targets

iSCSI data connection for mailboxes

Guidelines for upgrading the ONTAP Mediator in a MetroCluster configuration

If you are upgrading the ONTAP Mediator you must meet the Linux version requirements and follow guidelines for the upgrade.

  • The Mediator service can be upgraded from version from an immediately prior version to the current version.

  • All Mediator versions are supported on MetroCluster IP configurations running ONTAP 9.7 or later.

After the upgrade

After the Mediator and operating system upgrade is complete, you should issue the storage iscsi-initiator show command to confirm that the Mediator connections are up.