Do you use dbverify (dbv) against large datafiles to check for block corruption? Then chances are that you missed an 11gR1 New Feature: dbv can now divide one file into multiple parts and check them in parallel:
SQL> select * from v$version; BANNER -------------------------------------------------------------------------------- Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production PL/SQL Release 11.2.0.3.0 - Production CORE 11.2.0.3.0 Production TNS for Linux: Version 11.2.0.3.0 - Production NLSRTL Version 11.2.0.3.0 - Production SQL> col name for a50 SQL> select name,blocks from v$datafile; NAME BLOCKS -------------------------------------------------- ---------- /home/oracle/prima/system01.dbf 38400 /home/oracle/prima/sysaux01.dbf 25600 /home/oracle/prima/undotbs01.dbf 22912 /home/oracle/prima/users01.dbf 1280
My demo system is on 11.2.0.3, but the feature is already there in 11gR1, as the doc page here shows. See the parameters start and end there.
[oracle@uhesse1 ~]$ dbv file=/home/oracle/prima/users01.dbf start=1 end=500 DBVERIFY: Release 11.2.0.3.0 - Production on Mon Aug 20 21:59:28 2012 Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved. DBVERIFY - Verification starting : FILE = /home/oracle/prima/users01.dbf DBVERIFY - Verification complete Total Pages Examined : 500 Total Pages Processed (Data) : 11 Total Pages Failing (Data) : 0 Total Pages Processed (Index): 0 Total Pages Failing (Index): 0 Total Pages Processed (Other): 136 Total Pages Processed (Seg) : 0 Total Pages Failing (Seg) : 0 Total Pages Empty : 353 Total Pages Marked Corrupt : 0 Total Pages Influx : 0 Total Pages Encrypted : 0 Highest block SCN : 212814 (0.212814) [oracle@uhesse1 ~]$ dbv file=/home/oracle/prima/users01.dbf start=501 end=1280 DBVERIFY: Release 11.2.0.3.0 - Production on Mon Aug 20 22:10:16 2012 Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved. DBVERIFY - Verification starting : FILE = /home/oracle/prima/users01.dbf DBVERIFY - Verification complete Total Pages Examined : 780 Total Pages Processed (Data) : 0 Total Pages Failing (Data) : 0 Total Pages Processed (Index): 0 Total Pages Failing (Index): 0 Total Pages Processed (Other): 0 Total Pages Processed (Seg) : 0 Total Pages Failing (Seg) : 0 Total Pages Empty : 780 Total Pages Marked Corrupt : 0 Total Pages Influx : 0 Total Pages Encrypted : 0 Highest block SCN : 0 (0.0)
Granted, the file here is not large – but you should get the picture: I could have run the two dbv sessions from two different terminal windows in parallel as well. I realized from a recent twitter thread that this 11g New Feature that I teach since years is probably widely unknown – did you know it?
As always: Don’t believe it, test it! 🙂
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#1 von musingdba am August 21, 2012 - 02:26
Thanks Uwe.
This feature is something new to me. thanks for posting.
regards,
madhurendra
#2 von Gokhan Atil am August 21, 2012 - 17:35
Hey Uwe, nice idea! I wrote a small script about it:
http://www.gokhanatil.com/2012/08/dbverify-dbv-in-parallel.html
#3 von Uwe Hesse am August 25, 2012 - 08:43
madhurendra, you’re welcome 🙂
Gokhan, yes I saw that. Great follow up, thank you for sharing. This social media thing is really amazing, isn’t it? 🙂
#4 von Andrew Reid am November 27, 2012 - 01:12
Dear Uwe,
I liked this post so I translated it into Spanish here:
http://oracleenespanol.wordpress.com/2012/11/26/dbverify-en-modo-paralelo/
Incidentally, I think this was already available in Oracle 10.2.
Kind regards,
Andrew
#5 von Uwe Hesse am November 28, 2012 - 20:50
Hi Andrew,
thank you for the translation! I do not think that this was available in 10.2 – at least it is not documented: http://docs.oracle.com/cd/B19306_01/server.102/b14215/dbverify.htm#sthref1843
#6 von Prasad Avadhanam am April 28, 2016 - 16:16
If the activity is I/O bound, then, each task is already keeping disks 100% busy, does the parallel scanning really expedite the whole operation?