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Difference between revisions of "System Failover"

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The system failover is switching to a passive system when an active system is in a state of failure(e.g. hardware fault, network problem).
 
The system failover is switching to a passive system when an active system is in a state of failure(e.g. hardware fault, network problem).
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A passive system monitors the active system
 
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시스템 이중화란 두개의 장비를 Active-Passive 형태로 시스템을 유지하여 어느 한 장비의 장애 발생시 서비스의 연속성을 유지하기 위함입니다.<br>
 
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하나의 장비는 Active 모드로 그리고 다른 장비는 Passive 모드로 시작합니다.
 
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[[File:failover.png|400px|thumb|Failover 진행]]
 
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가상 IP 주소는 Active 장비에 항상 연결되어 장애 전환 이후에도 [[운영 서비스|서비스]]의 연속성을 보장합니다.
 
  
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Passive 모드 장비는 Active 장비를 수 초 간격으로 감지하며 지정된 시간(deadtime) 이상 Active 장비로 부터 응답이 없으면 Active 모드로 전환합니다. 또한 실시간 데이터베이스 동기화가 진행되어 장애 전환 이후 데이터의 연속성도 보장합니다.
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A passive system synchronizes all data from the master database in which is running in an active system by the Database Replication<ref>https://mariadb.com/kb/en/replication-overview/</ref> and monitors the active system.
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A passive system sends a heartbeat about every 10 seconds to monitor an active system. If the passive does not receive the response from an active system for the [[CLI - Configuring System Failover | Deadtime]], the passive system switches the mode to "active".
  
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Active / Passive 장비의 각 역할은 다음 표와 같습니다.
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[[File:failover.png|400px|thumb|Failover Flow]]
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You can connect the management page without changing the URI because a virtual IP is automatically configured in the active system by the [[ImRAD services(daemons) | failover service]].
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All services in the active and passive devices work as shown in the table below.
 
{| class="wikitable"
 
{| class="wikitable"
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! 역할 !! Active !! Passive
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! Service !! Active System !! Passive System
 
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| dhcpv4 || O || O
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| dhcpv4 || running || running
 
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|-
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| dhcpv6 || O || O
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| dhcpv6 || running || running
 
|-
 
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| radius || O || O
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| radius || running || running
 
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| logexp || 모든 역할 || 로컬 syslog만 저장
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| logexp || running  || running but only saves its Syslog.
 
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| failover || 가상 IP 설정 || Active 장비 감시
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| failover || Configuring a Virtual IP || Monitoring a active system and replicating the database
 
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| 데이터베이스 || Master || Slave
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| Database || Master || Slave
 
|-
 
|-
 
|}
 
|}
  
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failback은 지원하지 않으며 Active 장비가 장애 발생 후 다른 장비로 Active 모드가 전환된 이후 복구되면 Passive 모드로 전환됩니다(그림 마지막 단계).
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Note that, If an active system is recovered from a fault after another system has switched to the active mode, the recovered system switches to passive mode. In other words, The failback<ref>https://en.wikipedia.org/wiki/Failover</ref> does not occur.
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You can configure the System Failover via the [[CLI - Configuring System Failover | CLI]].
  
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이중화 설정은 CLI를 통해 설정할 수 있으며 "[[CLI - Configuring System Failover | Configuring System Failover]]"을 참고하세요.
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=== References ===

Revision as of 15:16, 16 April 2021

The system failover is switching to a passive system when an active system is in a state of failure(e.g. hardware fault, network problem).

A passive system synchronizes all data from the master database in which is running in an active system by the Database Replication[1] and monitors the active system. A passive system sends a heartbeat about every 10 seconds to monitor an active system. If the passive does not receive the response from an active system for the Deadtime, the passive system switches the mode to "active".

Failover Flow

You can connect the management page without changing the URI because a virtual IP is automatically configured in the active system by the failover service.

All services in the active and passive devices work as shown in the table below.

Service Active System Passive System
dhcpv4 running running
dhcpv6 running running
radius running running
logexp running running but only saves its Syslog.
failover Configuring a Virtual IP Monitoring a active system and replicating the database
Database Master Slave

Note that, If an active system is recovered from a fault after another system has switched to the active mode, the recovered system switches to passive mode. In other words, The failback[2] does not occur.

You can configure the System Failover via the CLI.

References

  1. ↑ https://mariadb.com/kb/en/replication-overview/
  2. ↑ https://en.wikipedia.org/wiki/Failover