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中级:dbv

原创 Linux操作系统 作者:cargoo 时间:2011-08-22 14:32:05 0 删除 编辑
Below are the definitions for each data item.
·     Total Pages Examined – The number of blocks inspected by dbv.  If the entire file was scanned, this value will match the BLOCKS column for the file in v$datafile.
·     Total Pages Processed (Data) –The number of blocks inspected by dbv that contained table data.
·     Total Pages Failing (Data) – The number of table blocks that have corruption.
·     Total Pages Processed (Index) –The number of blocks inspected by dbv that contained index data.
·     Total Pages Failing (Index) – The number of index blocks that are corrupted.
·     Total Pages Processed (Seg) – This output is new to 9i and allows the command to specify a segment that spans multiple files.
·     Total Pages Failing (Seg) – The number of segment data blocks that are corrupted.
·     Total Pages Empty – Number of unused blocks discovered in the file.
·     Total Pages Marked Corrupt – This is the most important one.  It shows the number of corrupt blocks discovered during the scan.
·     Total Pages Influx – The number of pages that were re-read due to the page being in use.  This should only occur when executing dbv against hot datafiles and should never occur when running dbv against cold backup files. 

< dbv.ksh
#!/bin/ksh
# Oracle Utilities
# dbv automation script
#
#
. oraenv
    wlogfile=dbv.${ORACLE_SID}
    SQLPLUS=${ORACLE_HOME}/bin/sqlplus
    $SQLPLUS -s  system/manager >> $wlogfile <       set echo off feedback off verify off pages 0 termout off   
           linesize 150
       spool dbv.cmd
       select 'dbv file=' || name || ' blocksize=' || block_size || ' feedback=' || round(blocks*.10,0) from v\$datafile;
       spool off
       set feedback on verify on pages24 echo on termout on    
EOF
ksh dbv.cmd
#
# End of script

db_block_checking=true – The default is false for this configuration parameter which is system modifiable:
ALTER SYSTEM SET DB_BLOCK_CHECKING = TRUE;
When true, Oracle performs block checks for all data blocks making sure that all data in the block is consistent.
Block checking provides early detection of block corruption, however, it costs between 1-10% in overhead on the database.  The more block writes that occur on a system (INSERT, UPDATE, DELETE), the more costly it becomes.  Any errors encountered by block checking result in an ORA-600 level message.  Before setting this parameter to TRUE, first execute dbv against the datafiles to make sure they are free of corruption.   Even when FALSE, Oracle still provides block checking for the system tablespace.

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