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Manual archiving of redo logs gone with 9i – or is it not?

Originally published on Dbvisit blog at http://blog.dbvisit.com/manual-archiving-of-redo-logs-gone-with-9i-or-is-it-not/.

If you memory dates back to the pre-10g times, you will maybe recall the steps to enable archivelog mode on the database at that time. Perhaps the greatest catch was that the online logs did not get archived automatically by default – you had to do it manually.

Or, let Oracle come to rescue, and let the ARCH process(es) do it for you by starting them with log_archive_start = true (or even dynamically with alter system archive log start/stop). You could even start ARCH in noarchivelog mode, so they did completely nothing, just writing error messages to alert.log.

One of the new features of 10g was getting rid of all of this – ARCH starting is governed solely by (no)archivelog mode and the DBA does not need to fiddle with anything else to get it right. Great applause, many thanks, scene over.

Well, all above is just a short transcript of my memory of those great times, and I lived with it happily and well till this week.

As it turns out, the story with 10g is not so straightforward – although it is true that if you just set no/archivelog mode that ARCH works as expected, the manual way of archiving was in fact not removed. But the way to enable it new:

To enable manual archiving mode, use alter database archivelog manual. The rest is the same as with 9i – use alter system archive log commands.

One consequence of this change – the log_mode in v$database can be archivelog, noarchivelog (as in 9i and before) or manual (from 10g on). This also means that if you want to detect whether a database runs in archivelog mode, you have to check for manual log_mode as well.

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