Replicating a disk to a standby versus replicating at the application level: what does the second give you?

Answer

A replicated disk (active/standby) keeps an exact copy, but only the active machine serves traffic, and the standby waits idle until failover. Application-level replication makes every copy a live, readable replica, so all of them serve reads, and the application can use quorums to keep writing with one copy down.

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