Archive logs? help?

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 Received on Fri Mar 07 2003 - 09:06:27 CST