Re: I need one opinion and one answer

to answer the question - the settings in init.ora on their own will not switch on archiving. You must start the database in Exclusive mode, then 'alter database archivelog' - then restart the database.

Alex

Neil May wrote:

> Raid5 should protect you from a data loss in the event of 1 disk
> failing. It won't protect you if you do something like :
>
> $ rm database_file
>
> You can recover from media failure if you have:
>
> 1. Lost archive logs, but have all the database files and online logs
> intact or
>
> 2. Lost some or all database files but have backups of them and ALL
> archivelogs since the backup was done. If you lose 1 archive log, you
> can only rollforward to that point.
>
> If you lose the current online log, you will lose some data and will
> need to recover all files from backup and rollforward. You don't want
> this to happen. This is why we mirror the online logs.
>
> Also, with raid, it stripes the data across all the drives in the raid
> set, so it doesn't really matter what file is on what disk. Raid5 also
> gives a significant write performance penalty, but reads perform well.
>
> Regards,
> Andrew.
>
> Van Messner wrote:
> >
> > Opinions Please
> >
> > I'm monitoring a group of databases running on Novell servers. Each
> > server has two disks (each with its own controller) which hold mirrored
> > control files and mirrored online redo logs. Everything else goes on the
> > server's raid5 setup - including the archived redo logs. This means I have
> > no control over which disks hold data, indexes, archived logs etc.
> > Normally I'd want to see the archived redo logs separate from the data
> > files (and even mirrored), but I don't know enough about raid5 to tell
> > whether we're protected against disk failure. The company takes a complete
> > cold backup of each database every night. But they say they can't afford to
> > lose part of a day's data if we crash after some of the redo logs have been
> > archived. Is this a danger or does raid5 protect us?
> >
> > Question
> >
> > For each database the init.ora file sets archiving on and sets a
> > destination for the archived redo logs. I can look at the alert log and see
> > that log switches take place with some regularity on each database. When I
> > do a backup controlfile to trace I see that nine of the databases have
> > archivemode set to yes and one has it set to no. The one that has it set to
> > no is not producing any archived redo logs. Since each database is shut
> > down, backed up and started again the following morning, and since each
> > init.ora sets archiving on, how or why does the one database not archive the
> > logs? Where is the setting being overridden?
> >
> > Thanks,
> > Van
Received on Thu Feb 11 1999 - 04:35:33 CST