Re: Archive logs? help?

"Norman Dunbar" <Norman.Dunbar_at_lfs.co.uk> wrote in message news:E2F6A70FE45242488C865C3BC1245DA70364DA5D_at_lnewton.leeds.lfs.co.uk...
> Hi James,
>
> In answer to your question, you only need the backup of the file(s) that
> are 'broken' and the appropraiet pile of archived logs since the start
> time of the hot backup you are recovering from. There is no need to
> recover ALL the datafiles and recover the database if there is only one
> datafile that is broken. Saves much time and effort and gets users back
> on-line quicker - they like that !
>
>
> when doing a hot backup you start (well, I do) by 'alter system archive
> log current' to get a fresh flush of the current logfile, which forces a
> new one to be used. You'll need to know the name, rank & serial number
> of this new one as it needs to stay with the hot backup files.
>
> Than slap each tablespace into backup mode ONE AT A TIME, copy it, take
> it out of backup mode. Repeat until finished. DON'T put all tablespaces
> into backup mode, copy them all etc - it just causes masses of archive
> logs to be generated ! (Read Only tablespaces should be dumped at the
> point they became read only, then they never need dumping again - unless
> you make them read-write again !)
>
> Do another' archive log current' at the end of the hot backup.
>
> Once you have taken the dump, all the hot backup files and all the
> archived logs from the start of the backup should be kept. The first one
> of course is the one you forced to be used with the initial 'archive log
> current' command. From this point onwards, until the next backup, you
> will need the datafile copies and the archived logs, all of them.
>
> When a restore is required, simply restore the datafile(s) that are
> actually broken, and either recover database or recover tablespace or
> even recover datafile 'blah' at which point, Oracle will tell you which
> log file it needs to begin the recovery.
>
> (God help me if I've made any errors in the above - I'll get a severe
> and well deserved telling off from Howard !)
>
> Basically, to do a recovery from hot backup dump files taken at time X,
> you need all the archived log files since the START of that hot backup
> to be available.
>
> If you have a 'spare' database lying around, take a hot backup, add some
> data to a tables or three, shut it down and delete a/the/some datafiles
> using the OS commands applicable, then do a recovery from your hot
> backup. Practice makes perfect (sometimes) and it is best to have tried
> it out on a totally unimportant database before you have to do it for
> real. Trust me, I know - junior dba, first day on job, senior dba left
> on the Friday previous with instructions for me to 'delete file xxx from
> the source database as the tablespace has been dropped' so I did. You
> can imagine the panic that then ensued as I work in a software house and
> that database is where the source code lives !!! I did, get a recovery
> with no loss of data in the end, but it took me a long time (until 02:00
> AM - I'd never heard of this NewsGroup then - wish I had !!)
>
> Cheers,
> Norman.
>
>
>
> -----Original Message-----
> From: James [mailto:james_at_nothing.com]
> Posted At: Friday, March 07, 2003 2:41 PM
> Posted To: server
> Conversation: Archive logs? help?
> Subject: Re: Archive logs? help?
>
>
> Thanks
> And just to confirm if I take a hot backup of the datafiles and the
> babkup
> files at the time and directly after the backup(that was 100%
> successful) I
> only have to restore the archive logs that I have just backed up and the
> datafiles. Is this true?
>
> cheers
> James
>
>
>

IMHO this is an excellent summary, Norman. Jonathan; any chance of adding this as an answer in the FAQ section?

Regards,
Paul Received on Sun Mar 09 2003 - 13:18:02 CST