Re: Backup en Caliente

> Yes, but, "ALTER SYSTEM ARCHIVE LOG CURRENT', moves online redo logs
> data to archived redo logs.

The point I'm getting at is that if you lose your entire system, you will also lose your archived redo logs unless you have a copy somewhere else.

> If I do a hot backup
> of tablespaces and control file ("alter database backup controlfile to
> 'd:\backup\controlAbr181158'; alter system switch logfile") and copy
> the archived redo logs and I try to recover until time
> '2006-04-18:11:58:04' (date created of controlAbr181158), I suppose
> that online redo logs are not required for recovering.

If you have the online redo logs, then you can use them for recovery, which would give you a *complete* recovery. If you do not have the online redo logs (or are missing some archived redo logs), then your only option left is *incomplete* recovery.

> I try this option because if there is a complete hardware failure I
> would lose the online redo logs too (although I had mirrored them).

Yes you would. And you would also lose any archived redo logs that are only available on that server.

> If I can not made a hot backup of online redo logs, but I have a hot
> backup of tablespaces files, control file and archived redo logs(at a
> given date), I try recovering without using online redo logs (if it's
> possible).

True enough.

> Although I lost the last changes (at least I could recover
> my database quickly at a date).

You will lose any changes made after your last archived redo log that you have available.

> I know this scenario is not very common, but I think it should be taken
> into account.

Actually, it's more common than you might think. Many DBAs do not give enough thought to their archived redo logs. Yes, they are archiving the redo logs on that server. And they may even dump those archived redo logs to tape or to another server on a daily basis. But that means they stand to lose up to one day's worth of changes to the database. Is that acceptable to your business? It may be acceptable. Or it may not. That is the question that must be answered when designing your backup (and recovery) strategy. If you can only lose an hour's worth of changes, then you must copy off your archived redo logs at least once an hour. If you cannot lose any database changes, then look into Data Guard. One thing that some DBA's do is to leverage the multiple archive log destination feature available in Oracle. Your redo logs get archived to your local server. And then they also can get archived to a remote server accessible through a cross mount. That way, should you lose your entire server, your archived redo logs, up until the last one that was created, can be found on the other server.

Note: A good backup strategy is worthless unless you also have a good recovery strategy to go along with it.

> (excuse me if not always I'm clear; English is not my native language).

No apologies necessary. Your English in this conversation has been very good. And definitely much, better than if I had to reply in Spanish!!! :)

And consider that much is lost if the correct terminology is not used. Those of us who grew up speaking and writing English suffer from that as well.

Cheers,
Brian

-- 
===================================================================

Brian Peasland
oracle_dba_at_nospam.peasland.net
http://www.peasland.net

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