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Re: backup of large databases

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Date: Fri, 26 Oct 2001 11:19:43 -0700
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We have a 180 Gig database on Sun Solaris 2.6, version 8.0.4 of Oracle.

We use RMAN and Veritas to back up to tape. Archiving is turned on.

Full hot backups are done once a week. Incremental backups are done at mid-week. It takes about eight hours to do the full backup to tape.

We used to run an hourly RMAN job that would back up our archive files to tape and then delete them from disk. We found that with the few recoveries
that we've had to do, the part that took the most time was the robot finding and mounting
the tapes that contained the archive files. Our goal is to decrease the number
of archive files that we have to get off of tape, thereby decreasing our mean time to recover.

We requested additional disk in order to be able to keep a weeks worth of archives on hand. The reality is that we have occasssional peaks of activity that have frequently caused us to run through most of our archive directory in a single day. We're still trying to tweak the interval
between archive backup jobs.

Our agreement with the users of this database is that we will complete a database recovery within 12 hours. To this point, we've been successful in doing so with the three recoveries that we've had to do.

We've told the users that if they want a faster recovery time, we will need to implement BCVs (we have EMC disk) or some other, more expensive solution.

We also do a weekly logical backup using export piped to split UNIX files. We have not had to do a logical recovery on this database yet. Since it is a data warehouse, it is probably faster for them to reload a day's worth of
data than it us for us to truncate some of the larger tables and re-import the
data from a dump.

We also do a daily export of just the structure of the data objects without the
rows of data.

We do not do cold backups on this database.

Cherie Machler
Oracle DBA
Gelco Information Network

                    "Ed Lewis"                                                         
                    <eglewis_at_hotma       To:     Multiple recipients of list ORACLE-L 
          >              cc:                                           
                    Sent by:             Subject:     backup of large databases        
                    10/26/01 01:51                                                     
                    Please respond                                                     
                    to ORACLE-L                                                        


    I'm curious how people handle the backups for     large/very large databases; 200gb or greater.

    My questions are not targeted towards any     specific hardware platform, but we are using     Oracle 8.1.7. I'm assuming that archiving is enabled.

    Are backups done nightly, or because of     time constraints are they done weekly ?     If weekly, do you feel comfortable having to possibly     apply a week of archives, in the case of a recovery ?

    Do you use disk or tape ?

    Do you use RMAN or other backup tools ?

    What are the customer's expections for recovery and     how do they effect your backup strategy ?

    I appreciate your input.



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