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by napsterbr
622 days ago
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> Do I need 2 replicas to avoid the split brain scenario? my brain hurts already. It will hurt even more. The recommended way is to set up a witness server. Yet another thing to manage in a properly designed Postgres cluster. Certainly not an easy/trivial thing to do, ops-wise. From [0]: > By creating a witness server in the same location (data centre) as the primary, if the primary becomes unavailable it's possible for the standby to decide whether it can promote itself without risking a "split brain" scenario: if it can't see either the witness or the primary server, it's likely there's a network-level interruption and it should not promote itself. If it can see the witness but not the primary, this proves there is no network interruption and the primary itself is unavailable, and it can therefore promote itself (and ideally take action to fence the former primary). An interesting acronym you'll hear is STONITH (in order to fence the former primary). [0] - https://www.repmgr.org/docs/current/repmgrd-witness-server.h... |
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