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Q-SYS Redundancy

Overview

There are four types of redundancy available in a Q-SYS system:

• Network Redundancy
• Core Redundancy
• I/O Peripheral Redundancy
• Amplifier Redundancy

Network Redundancy

The Core, and each Q-SYS peripheral device (I/O Frame), has 2 LAN ports: LAN A and LAN B. LAN A is the default, primary port, LAN B the backup or redundant. Each audio peripheral can be configured in Q-SYS Designer to use LAN B as a backup (Is Network Redundant). For each audio peripheral that "Is Network Redundant" (uses LAN B), the Core establishes redundant audio streams to and from that peripheral. These streams are always active, allowing the Core and peripherals to use the audio streams from LAN B if there is a problem with LAN A. If a port, switch, or link is lost, there is no failover time, and no interruption of the audio stream.

The control communication streams, while not necessarily constantly replicated over the two ports, will also failover seamlessly.

NOTE:  The Core only establishes redundant audio and control streams with those peripherals that are configured in Q-SYS Designer as "Is Network Redundant" (using LAN B). This means that those peripherals not configured and physically wired, to use both LAN ports, cannot make use of network redundancy.

There are network configuration and topology considerations to understand when implementing Q-SYS Network Redundancy, refer to Q-LAN Networking.

Core Redundancy

A second or Backup Core can be paired with the Primary Core in an installation. There is a configuration option in the Core Properties in Q-SYS Designer to match the hardware installation. Initially, the Primary Core is the Active Core, and the Backup Core is the Standby Core.

In a Core-redundant system, the Standby Core is responsible for constantly communicating with the Active Core so as to verify the health of the Active Core, and to synchronize its control settings, snapshots and event schedules with the Active Core. The Standby Core also communicates with the peripherals so as to verify its readiness to take over. If the Standby Core detects a fault with the Active Core, it establishes full audio streaming and control communications with peripherals and becomes the "active" Core. If the Primary, for whatever reason, does not actually go into standby during a failover, the Backup has priority and remains the Active Core. After a failover, Q-SYS does not automatically change back to the failed Core when the Core recovers. This is to prevent additional audio gaps. You can manually change back at an appropriate time.

During a failover, the audio peripherals are muted, and are un-muted once the backup becomes active. An automatic failover, in which the backup must automatically decide to go active, takes about 10 seconds. If the backup is manually instructed to go active, the process takes about 3 seconds.

NOTE:  Failover time has not yet been tested with large systems.

Both the primary and backup Cores must be present and online during system installation so that both get configured with the proper design data.

Core Redundancy Limitations

• A CobraNet card in a Core which is in standby is not automatically suppressed from transmitting and receiving. This might affect your ability to use a redundant pair of Cores populated with CobraNet cards.
• If the Primary Core is set to the highest-priority clock master and the backup Core set to the second highest-priority, there is a short audio stream dropout if the Primary Core loses connection to the network or is rebooted.

I/O Frame Redundancy

A second or backup I/O Frame can be paired with another I/O Frame for redundancy. You can have redundancy for one to all of the I/O Frames in an installation. The Core monitors the status of the I/O Frames. If there is a problem detected with a primary I/O Frame, the Core directs the backup I/O Frame to take over.

I/O Card and GPIO Requirements

Both the Core and I/O Frame can have any of the various I/O cards installed in the available slots. Redundancy for individual I/O cards within a single I/O Frame is not supported. Each of the available cards are listed below with their requirements for I/O Frame or Core redundancy.

• AES3 Input / Output - AES3 Outputs do not wire together - you must physically switch the output cabling on failover.
• DataPort Out - You must use the DataPort Amplifier Backup panel and have redundant amplifiers. The DataPort card outputs cannot be wired in parallel.
• Mic Line Out - Wire the outputs of the Line Out card in parallel
• Mic/Line In - Wire the inputs of the Mic/Line In card in parallel, for active circuitry devices requiring phantom power, and devices not requiring phantom power such as dynamic microphones.

NOTE:  When phantom power is used, the active circuitry device gets the average of both Mic/Line In card's phantom power, which is +48 VDC. When a failover occurs, the device again gets the average of both Mic/Line In card's phantom power (+48 VDC and 0 VDC) + 24 VDC which should be enough to operate the device.

• GPIO - Wire the GPIO pins in parallel except when you are using a high impedance analog source such as a potentiometer.

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