Standby Database

[jmodic]

It does not need to know which SCN is in which archived log file. All it needs to know is which is the first redo log that has not yet been recorded in one of the database files, but has allready been checkponted in some of the other database files or in the controlfile.

[LND]

"how does Oracle know that certain SCN is in certain archived log therefore it needs the corresponding archived log for recovery" - I guess Oracle knows SCN just by using formula last_scn_from_last_applied_log+1,
and knows log number just from log_sequence_no_from_last_applied_log+1 (some issues regarding OPS may be here?)

[jrpm]

Why would you want the standby in noarchive?

Presumptively, it will take over when the primary fails. Won't there be transactions processed by the secondary? If it fails, won't you want the archive logs to recover (assuming the primary is not yet ready?) Depending on the failure mode, won't you need them to bring the primary back up to speed until you switch processing back?