201 · Question #54
Assuming other failover settings are at their default state, what would occur if the failover cable were to be disconnected for five seconds and then reconnected.
The correct answer is C. When the cable is disconnected, both systems will become active. When the voltage is restored, unit two. If the failover cable is disconnected, both systems will become active due to loss of communication; upon reconnection, the systems will negotiate roles, with one typically reverting to standby.
Question
Assuming other failover settings are at their default state, what would occur if the failover cable were to be disconnected for five seconds and then reconnected.
Options
- AAs long as network communication is not lost, no change will occur.
- BNothing. Failover due to loss of voltage will not occur if the voltage is lost for less than ten seconds.
- CWhen the cable is disconnected, both systems will become active. When the voltage is restored, unit two
- DWhen the cable is disconnected, both systems will become active. When the voltage is restored, both
How the community answered
(65 responses)- A11% (7)
- B5% (3)
- C82% (53)
- D3% (2)
Why each option
If the failover cable is disconnected, both systems will become active due to loss of communication; upon reconnection, the systems will negotiate roles, with one typically reverting to standby.
Loss of the failover cable, which provides a dedicated heartbeat, is a critical failover event regardless of other network connectivity.
Failover is triggered by the loss of the failover cable's heartbeat, not specifically voltage loss, and default timeouts are typically shorter than ten seconds.
When the failover cable is disconnected, both systems lose communication and independently assume they are the only active unit, resulting in a split-brain scenario where both become active. Upon reconnection, the units negotiate roles, typically with the lower-priority or higher-ID unit reverting to standby.
While both systems becoming active is correct upon disconnection, the resolution process upon reconnection typically results in one unit becoming standby, not both remaining active.
Concept tested: BIG-IP HA failover cable split-brain
Source: https://techdocs.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/bigip-concepts-11-2-0/bigip-ha-concepts.html
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