Re: benefits of multiple switch logfile calls?

"lsattle" <lsattle_at_yahoo.com> wrote in message news:95898986.0312061724.322dd9b2_at_posting.google.com...

> I will have to do some homework on what you are saying. I agree,
> using the trace (non binary) version of the controlfile will work
> (I've proved it during cloning). However you are coming across as
> expert with all the answers.

There might be a reason for that.

>My orignal intention of posting against
> the original message was that I have found Oracle's older writeups to
> have holes.

Certainly.

>I never remember seeing them say to not bu and restore
> the online redo logs (but one of their documents we looked at this
> week did say to skip the online redo logs). Maybe I'm wrong, I have
> some old doc from the mid nineties (class material also) and I will
> look it up.

It pays to keep current. I dread to think of the nonsense that was taught in 8.0 Performance Tuning. It's still not perfect, but at least these days they are strongly dissuading people from Buffer Cache Hit Ratio tuning approaches. But the 8.0 backup and recovery stuff was pretty sound, and I don't remember any particular howlers. Before that... dunno. But I wouldn't be applying version 7 backup and recovery techniques to an 8.0+ database, regardless.

> In totality I'm reading your bone of contention to be that I restore
> the binary control file and use it in the recovery (at D/R). What I'm
> not sure of is where / why you are saying I am at risk.

Because (RMAN excepted) there is seldom a need to use the binary version of the backup controlfile; because doing so requires a resetlogs; because a resetlogs renders all prior backups and archive logs redundant; therefore a resetlogs requires an immediate new backup to be taken; therefore your database is vulnerable to a further failure until that backup is complete; and that none of that risk and expense need be incurred in the first place.

And mainly because the actions one takes when performing recovery should depend on the nature of the failure, or the nature of the result required, not something which originally came across as a one-size-fits-all, lowest-common-denominator, mis-use of recovery commands.

> Why does oracle provide a backup command to back up the binary
> controlfile?

Because there are certain occasions when it might be appropriate!

>
> You come across as an expert with "the only way". How many d/r
> recoveries have tested / proved out?

Then you're reading me wrong. Everyone is entitled to find a backup and recovery scenario which works for them, and which they are happy with. All I'm saying is that this isn't, or shouldn't, be 'fumble in the dark' stuff. The consistency and recovery mechanisms which Oracle uses are quite well documented, easily understood, and a scientific approach to backup and recovery is therefore perfectly attainable. That, as a result, whichever backup and recovery strategy you opt for should be based on those scientific principles, should be logical, robust and capable of withstanding changing circumstances.

And that in a public forum, one should push 'best practice', not stuff which happens to work for a particular person/organisation with a particular set-up, the subtle details of which we can never really find out here.

Regards
HJR

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