Re: Issues Outstanding for Point In Time Recovery (PITR)

I know that in Oracle there are 'alter database begin backup' and 'alter 
database end backup' commands that allow you to script your hot backups 
through a cron job by calling the begin backup command first, then using 
disk backup method of choice and then finally call the end backup command.

--Barry

Patrick Macdonald wrote:

>Zeugswetter Andreas SB SD wrote:
>  
>
>>>As noted, one of the main problems is knowing where to begin
>>>in the log.  This can be handled by having backup processing
>>>update the control file with the first lsn and log file
>>>required.  At the time of the backup, this information is or
>>>can be made available.  The control file can be the last file
>>>added to the tar and can contain information spanning the entire
>>>backup process.
>>>      
>>>
>>lsn and logfile number (of latest checkpoints) is already in the control
>>file, thus you need control file at start of backup. (To reduce the number
>>of logs needed for restore of an online backup you could force a checkpoint
>>before starting file backup)
>>    
>>
>
>Maybe I should have been more clear.  The control file snapshot must 
>be taken at backup start (as you mention) but can be stored in cache.
>The fields can then be modified as we see fit.  At the end of backup,
>we can write this to a temp file and add it to the tar.  Therefore,
>as mentioned, the snapshot spans the entire backup process.
> 
>  
>
>>You will also need lsn and logfile number after file backup, to know how much
>>log needs to at least be replayed to regain a consistent state.
>>    
>>
>
>This is a nicety but not a necessity. If you have a backup end log 
>record, you just have to enforce that the PIT recovery encounters 
>that particular log record on forward recovery.  Once encountered,
>you know that you at passed the point of back up end.
>
>Cheers,
>Patrick
>
>
>
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