Module 12: High Availability Lesson 1:High Availability Flashcards
(16 cards)
What is high availability?
A system or component that is continuously operational for a long length of time
What is fault tolerance?
A system or component that is designed so that, if a component fails, a backup component or procedure can immediately take its place with no loss of service
What is the five 9s?
A widely held standard of availability
If your systems must be 99 percent available, how much downtime can you afford for both planned and unplanned downtime?
3.5 days per year
HA provides the ______ of virtual machines in case of physical host failures.
HA provides the restart of virtual machines in case of physical host failures.
A cluster enabled for HA and DRS can have up to how many hosts per cluster?
32
A cluster enabled for HA and DRS can have up to how many virtual machines per host?
320
A cluster enabled for HA and DRS can have up to how many virtual machines per cluster?
3,000
How does FT work?
It creates a duplicate copy of each running virtual machine
What could happen if HA admission control is turned off and DPM is enabled?
It could power off hosts leaving fewer resources available
How does HA check host status?
Through the exchange of heartbeats
By default, how often do heartbeats get exchanged?
Every second
By default, how much time must pass with no response before a host is declared as failed?
15 seconds
By default, how much time must pass with no responses from other hosts before a host declares itself as failed?
12 seconds
What is the first thing a host will do after it does not receive any responses from other hosts for 12 seconds?
It will attempt to ping the isolation address
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