RE: Choosing data file size for a multi TB database?

  • From: Branimir Petrovic <BranimirP@xxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Fri, 2 Sep 2005 18:54:02 -0400

What about checkpoint against tens of thousands of data files, surely 
more-merrier rule holds? For that reason (or due to a fear factor) I 
was under may be false impression that smaller number (in hundreds) 
of relatively larger data files (20 GB or so) might be better choice. 
Other very real problem with 10TB database I can easily foresee, but 
for which I do not know proper solution, is how would one go about the
business of regular verification of taped backup sets? Have another 
humongous hardware just for that purpose? Fully trust the rust? (i.e. 
examine backup logs and never try restoring, or...) What do people 
do to ensure multi TB monster databases are surely and truly safe 
and restorable/rebuildable?

-----Original Message-----
From: Tim Gorman [mailto:tim@xxxxxxxxx]
Sent: Friday, September 02, 2005 5:59 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: Re: Choosing data file size for a multi TB database?

Datafile sizing has the greatest regular impact on backups and restores.
Given a large multi-processor server with 16 tape drives available, which
would do a full backup or full restore fastest?

*       a 10-Tbyte database comprised of two 5-Tbyte datafiles 

*       a 10-Tbyte database comprised of ten 1-Tbyte datafiles 

*       a 10-Tbyte database comprised of two-hundred 50-Gbyte datafiles? 

*       a 10-Tbyte database comprised of two-thousand 5-Gbyte datafiles?

Be sure to consider what type of backup media are you using, how much
concurrency will you be using, and the throughput of each device?

There is nothing "unmanageable" about hundreds or thousands of datafiles;
don't know why that's cited as a concern.  Oracle8.0 and above has a
limitation on 65,535 datafiles per tablespace, but otherwise large numbers
of files are not something to be concerned about.  Heck, the average
distribution of a Java-based application is comprised of 42 million
directories and files and nobody ever worries about it...

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