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> Chapter 13 - High Availability > An introduction to the FGCP > Disk storage configuration and HA

Disk storage configuration and HA

If your cluster units include storage disks (for example for storing log messages, WAN optimization data and web caching) all cluster units must have identical storage disk configurations. This means each cluster unit must have same number of disks (including AMC and FortiGate Storage Module (FSM) hard disks) and also means that matching disks in each cluster unit must be the same size, have the same format, and have the same number of partitions.

In most cases the default hard disk configuration of the cluster units will be compatible. However, a hard disk formatted by an older FortiGate firmware version may not be compatible with a hard disk formatted by a more recent firmware version. Problems may also arise if you have used the execute scsi-dev command to add or change hard disk protections.

If a cluster unit CLI displays hard disk compatibility messages, you may need to use the execute scsi-dev delete command to delete partitions. You can also use the execute formatlogdisk command to reformat disks. In some cases after deleting all partitions and reformatting the disks, you may still see disk incompatibility messages. If this happens, contact Fortinet Customer Support for assistance.

Heartbeat interfaces

Fortinet suggests the following practices related to heartbeat interfaces:

Do not use a FortiGate switch port for the HA heartbeat traffic. This configuration is not supported.
  • For clusters of two FortiGate units, as much as possible, heartbeat interfaces should be directly connected using patch cables (without involving other network equipment such as switches). If switches have to be used they should not be used for other network traffic that could flood the switches and cause heartbeat delays.
  • If you cannot use a dedicated switch, the use of a dedicated VLAN can help limit the broadcast domain to protect the heartbeat traffic and the bandwidth it creates.
  • For clusters of three or four FortiGate units, use switches to connect heartbeat interfaces. The corresponding heartbeat interface of each FortiGate unit in the cluster must be connected to the same switch. For improved redundancy use a different switch for each heartbeat interface. In that way if the switch connecting one of the heartbeat interfaces fails or is unplugged, heartbeat traffic can continue on the other heartbeat interfaces and switch.
  • Isolate heartbeat interfaces from user networks. Heartbeat packets contain sensitive cluster configuration information and can consume a considerable amount of network bandwidth. If the cluster consists of two FortiGate units, connect the heartbeat interfaces directly using a crossover cable or a regular Ethernet cable. For clusters with more than two units, connect heartbeat interfaces to a separate switch that is not connected to any network.
  • If heartbeat traffic cannot be isolated from user networks, enable heartbeat message encryption and authentication to protect cluster information. See Enabling or disabling HA heartbeat encryption and authentication.
  • Configure and connect redundant heartbeat interfaces so that if one heartbeat interface fails or becomes disconnected, HA heartbeat traffic can continue to be transmitted using the backup heartbeat interface. If heartbeat communication fails, all cluster members will think they are the primary unit resulting in multiple devices on the network with the same IP addresses and MAC addresses (condition referred to as Split Brain) and communication will be disrupted until heartbeat communication can be reestablished.
  • Do not monitor dedicated heartbeat interfaces; monitor those interfaces whose failure should trigger a device failover.
  • Where possible at least one heartbeat interface should not be connected to an NPx processor to avoid NPx-related problems from affecting heartbeat traffic.

Interface monitoring (port monitoring)

Fortinet suggests the following practices related to interface monitoring (also called port monitoring):

  • Wait until a cluster is up and running and all interfaces are connected before enabling interface monitoring. A monitored interface can easily become disconnected during initial setup and cause failovers to occur before the cluster is fully configured and tested.
  • Monitor interfaces connected to networks that process high priority traffic so that the cluster maintains connections to these networks if a failure occurs.
  • Avoid configuring interface monitoring for all interfaces.
  • Supplement interface monitoring with remote link failover. Configure remote link failover to maintain packet flow if a link not directly connected to a cluster unit (for example, between a switch connected to a cluster interface and the network) fails. See Remote link failover.


The following sections in this document contain troubleshooting information:

FGCP HA terminology

The following HA-specific terms are used in this document.


A group of FortiGate units that act as a single virtual FortiGate unit to maintain connectivity even if one of the FortiGate units in the cluster fails.

Cluster unit

A FortiGate unit operating in a FortiGate HA cluster.

Device failover

Device failover is a basic requirement of any highly available system. Device failover means that if a device fails, a replacement device automatically takes the place of the failed device and continues operating in the same manner as the failed device.


A FortiGate unit taking over processing network traffic in place of another unit in the cluster that suffered a device failure or a link failure.


A hardware or software problem that causes a FortiGate unit or a monitored interface to stop processing network traffic.


The FortiGate clustering protocol (FGCP) that specifies how the FortiGate units in a cluster communicate to keep the cluster operating.

Full mesh HA

Full mesh HA is a method of removing single points of failure on a network that includes an HA cluster. FortiGate models that support redundant interfaces can be used to create a cluster configuration called full mesh HA. Full mesh HA includes redundant connections between all network components. If any single component or any single connection fails, traffic switches to the redundant component or connection.

HA virtual MAC address

When operating in HA mode, all of the interfaces of the primary unit acquire the same HA virtual MAC address. All communications with the cluster must use this MAC address. The HA virtual MAC address is set according to the group ID.


Also called FGCP heartbeat or HA heartbeat. The heartbeat constantly communicates HA status and synchronization information to make sure that the cluster is operating properly.

Heartbeat device

An Ethernet network interface in a cluster that is used by the FGCP for heartbeat communications among cluster units.

Heartbeat failover

If an interface functioning as the heartbeat device fails, the heartbeat is transferred to another interface also configured as an HA heartbeat device.

Hello state

In the hello state a cluster unit has powered on in HA mode, is using HA heartbeat interfaces to send hello packets, and is listening on its heartbeat interfaces for hello packets from other FortiGate units. Hello state may appear in HA log messages.

High availability

The ability that a cluster has to maintain a connection when there is a device or link failure by having another unit in the cluster take over the connection, without any loss of connectivity. To achieve high availability, all FortiGate units in the cluster share session and configuration information.

Interface monitoring

You can configure interface monitoring (also called port monitoring) to monitor FortiGate interfaces to verify that the monitored interfaces are functioning properly and connected to their networks. If a monitored interface fails or is disconnected from its network the interface leaves the cluster and a link failover occurs. For more information about interface monitoring, see Link failover (port monitoring or interface monitoring).

Link failover

Link failover means that if a monitored interface fails, the cluster reorganizes to re-establish a link to the network that the monitored interface was connected to and to continue operating with minimal or no disruption of network traffic.

Load balancing

Also known as active-active HA. All units in the cluster process network traffic. The FGCP employs a technique similar to unicast load balancing. The primary unit interfaces are assigned virtual MAC addresses which are associated on the network with the cluster IP addresses. The primary unit is the only cluster unit to receive packets sent to the cluster. The primary unit can process packets itself, or propagate them to subordinate units according to a load balancing schedule. Communication between the cluster units uses the actual cluster unit MAC addresses.

Monitored interface

An interface that is monitored by a cluster to make sure that it is connected and operating correctly. The cluster monitors the connectivity of this interface for all cluster units. If a monitored interface fails or becomes disconnected from its network, the cluster will compensate.

Primary unit

Also called the primary cluster unit, this cluster unit controls how the cluster operates. The primary unit sends hello packets to all cluster units to synchronize session information, synchronize the cluster configuration, and to synchronize the cluster routing table. The hello packets also confirm for the subordinate units that the primary unit is still functioning.

The primary unit also tracks the status of all subordinate units. When you start a management connection to a cluster, you connect to the primary unit.

In an active-passive cluster, the primary unit processes all network traffic. If a subordinate unit fails, the primary unit updates the cluster configuration database.

In an active-active cluster, the primary unit receives all network traffic and re-directs this traffic to subordinate units. If a subordinate unit fails, the primary unit updates the cluster status and redistributes load balanced traffic to other subordinate units in the cluster.

The FortiGate firmware uses the term master to refer to the primary unit.

Session failover

Session failover means that a cluster maintains active network sessions after a device or link failover. FortiGate HA does not support session failover by default. To enable session failover you must change the HA configuration to select Enable Session Pick-up.

Session pickup

If you enable session pickup for a cluster, if the primary unit fails or a subordinate unit in an active-active cluster fails, all communication sessions with the cluster are maintained or picked up by the cluster after the cluster negotiates to select a new primary unit.

If session pickup is not a requirement of your HA installation, you can disable this option to save processing resources and reduce the network bandwidth used by HA session synchronization. In many cases interrupted sessions will resume on their own after a failover even if session pickup is not enabled. You can also enable session pickup delay to reduce the number of sessions that are synchronized by session pickup.

Standby state

A subordinate unit in an active-passive HA cluster operates in the standby state. In a virtual cluster, a subordinate virtual domain also operates in the standby state. The standby state is actually a hot-standby state because the subordinate unit or subordinate virtual domain is not processing traffic but is monitoring the primary unit session table to take the place of the primary unit or primary virtual domain if a failure occurs.

In an active-active cluster all cluster units operate in a work state.

When standby state appears in HA log messages this usually means that a cluster unit has become a subordinate unit in an active-passive cluster or that a virtual domain has become a subordinate virtual domain.

State synchronization

The part of the FGCP that maintains connections after failover.

Subordinate unit

Also called the subordinate cluster unit, each cluster contains one or more cluster units that are not functioning as the primary unit. Subordinate units are always waiting to become the primary unit. If a subordinate unit does not receive hello packets from the primary unit, it attempts to become the primary unit.

In an active-active cluster, subordinate units keep track of cluster connections, keep their configurations and routing tables synchronized with the primary unit, and process network traffic assigned to them by the primary unit. In an active-passive cluster, subordinate units do not process network traffic. However, active-passive subordinate units do keep track of cluster connections and do keep their configurations and routing tables synchronized with the primary unit.

The FortiGate firmware uses the terms slave and subsidiary unit to refer to a subordinate unit.

Virtual clustering

Virtual clustering is an extension of the FGCP for FortiGate units operating with multiple VDOMS enabled. Virtual clustering operates in active-passive mode to provide failover protection between two instances of a VDOM operating on two different cluster units. You can also operate virtual clustering in active-active mode to use HA load balancing to load balance sessions between cluster units. Alternatively, by distributing VDOM processing between the two cluster units you can also configure virtual clustering to provide load balancing by distributing sessions for different VDOMs to each cluster unit.

Work state

The primary unit in an active-passive HA cluster, a primary virtual domain in a virtual cluster, and all cluster units in an active-active cluster operate in the work state. A cluster unit operating in the work state processes traffic, monitors the status of the other cluster units, and tracks the session table of the cluster.

When work state appears in HA log messages this usually means that a cluster unit has become the primary unit or that a virtual domain has become a primary virtual domain.

HA web-based manager options

Go to System > Config > HA to change HA options. You can set the following options to put a FortiGate unit into HA mode. You can also change any of these options while the cluster is operating.

You can configure HA options for a FortiGate unit with virtual domains (VDOMs) enabled by logging into the web-based manager as the global admin administrator and going to System > Config > HA.

If already operating in HA mode, go to System > Config > HA to display the cluster members list (see Cluster members list).

Go to System > Config > HA and select View HA Statistics to view statistics about cluster operation. See Viewing HA statistics.

If your cluster uses virtual domains, you are configuring HA virtual clustering. Most virtual cluster HA options are the same as normal HA options. However, virtual clusters include VDOM partitioning options. Other differences between configuration options for regular HA and for virtual clustering HA are described below and see Virtual clusters.
FortiGate HA is compatible with DHCP and PPPoE but care should be taken when configuring a cluster that includes a FortiGate interface configured to get its IP address with DHCP or PPPoE. Fortinet recommends that you turn on DHCP or PPPoE addressing for an interface after the cluster has been configured. If an interface is configured for DHCP or PPPoE, turning on high availability may result in the interface receiving an incorrect address or not being able to connect to the DHCP or PPPoE server correctly.

Select an HA mode for the cluster or return the FortiGate unit in the cluster to standalone mode. When configuring a cluster, you must set all members of the HA cluster to the same HA mode. You can select Standalone (to disable HA), Active-Passive, or Active-Active.

If virtual domains are enabled you can select Active-Passive or Standalone.

Device Priority

Optionally set the device priority of the cluster FortiGate unit. Each FortiGate unit in a cluster can have a different device priority. During HA negotiation, the FortiGate unit with the highest device priority usually becomes the primary unit.

In a virtual cluster configuration, each cluster FortiGate unit can have two different device priorities, one for each virtual cluster. During HA negotiation, the FortiGate unit with the highest device priority in a virtual cluster becomes the primary FortiGate unit for that virtual cluster.

Changes to the device priority are not synchronized. You can accept the default device priority when first configuring a cluster.

Reserve Management Port for Cluster Member

You can provide direct management access to individual cluster units by reserving a management interface as part of the HA configuration. Once this management interface is reserved, you can configure a different IP address, administrative access and other interface settings for this interface for each cluster unit. Then by connecting this interface of each cluster unit to your network you can manage each cluster unit separately from a different IP address. See Managing individual cluster units using a reserved management interface.

Group Name

Enter a name to identify the cluster. The maximum length of the group name is 32 characters. The group name must be the same for all cluster units before the cluster units can form a cluster. After a cluster is operating, you can change the group name. The group name change is synchronized to all cluster units.


Enter a password to identify the cluster. The password must be the same for all cluster FortiGate units before the cluster FortiGate units can form a cluster.

Two clusters on the same network must have different passwords.

The password is synchronized to all cluster units in an operating cluster. If you change the password of one cluster unit the change is synchronized to all cluster units.

Enable Session pickup

Select to enable session pickup so that if the primary unit fails, sessions are picked up by the cluster unit that becomes the new primary unit.

You must enable session pickup for session failover protection. If you do not require session failover protection, leaving session pickup disabled may reduce HA CPU usage and reduce HA heartbeat network bandwidth usage. See Session failover (session pick-up).

Port Monitor

Select to enable or disable monitoring FortiGate interfaces to verify the monitored interfaces are functioning properly and are connected to their networks. See Link failover (port monitoring or interface monitoring).

If a monitored interface fails or is disconnected from its network, the interface leaves the cluster and a link failover occurs. The link failover causes the cluster to reroute the traffic being processed by that interface to the same interface of another cluster FortiGate unit that still has a connection to the network. This other cluster FortiGate unit becomes the new primary unit.

Port monitoring (also called interface monitoring) is disabled by default. Leave port monitoring disabled until the cluster is operating and then only enable port monitoring for connected interfaces.

You can monitor up to 64 interfaces.

Heartbeat Interface

Select to enable or disable HA heartbeat communication for each interface in the cluster and set the heartbeat interface priority. The heartbeat interface with the highest priority processes all heartbeat traffic. If two or more heartbeat interfaces have the same priority, the heartbeat interface with the lowest hash map order value processes all heartbeat traffic. The web-based manager lists interfaces in alphanumeric order:

  • port1
  • port2 through 9
  • port10

Hash map order sorts interfaces in the following order:

  • port1
  • port10
  • port2 through port9

The default heartbeat interface configuration is different for each FortiGate model. This default configuration usually sets the priority of two heartbeat interfaces to 50. You can accept the default heartbeat interface configuration or change it as required.

The heartbeat interface priority range is 0 to 512. The default priority when you select a new heartbeat interface is 0.

You must select at least one heartbeat interface. If heartbeat communication is interrupted, the cluster stops processing traffic. See HA heartbeat and communication between cluster units.

You can select up to 8 heartbeat interfaces. This limit only applies to units with more than 8 physical interfaces.

VDOM partitioning

If you are configuring virtual clustering, you can set the virtual domains to be in virtual cluster 1 and the virtual domains to be in virtual cluster 2. The root virtual domain must always be in virtual cluster 1.