Hello Friends,
Here with one more topic on.
Fencing Basics - Node Eviction in Oracle RAC || Real Application Cluster:
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Why are nodes evicted?
• Evicting (fencing) nodes is a preventive measure (it’s a good thing)!
• Nodes are evicted to prevent consequences of a split brain:
- Shared data must not be written by independently operating nodes
- The easiest way to prevent this is to forcibly remove a node from the cluster
How are nodes evicted? - STONITH
EXAMPLE: Network heartbeat failure
What happens, if CSSD is stuck?
How can nodes be evicted?
EXAMPLE: IPMI based eviction on heartbeat failure
Which node gets evicted?
Cluster members can escalate a kill request
Re-Bootless Node Fencing
EXCEPTIONS
• With Oracle Clusterware 11.2.0.2, re-boots will be seen less, unless…:
- IF the check for a successful kill of the IO processes fails → reboot
- IF CSSD gets killed during the operation → reboot
- IF cssdmonitor (oprocd replacement) is not scheduled → reboot
- IF the stack cannot be shutdown in “short_disk_timeout”-seconds → reboot
#Fencing #NodeEviction #exadata #oracle #oracledatabase #oracledba #rac #database #databaseadministration #databases
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26 июн 2020
