DBVERIFY: Database Verification Utility

DBVERIFY is a utility of Oracle , that can be used to perform a physical structure integrity check against database files.


Note that the database should be off line before performing a DBVERIFY.
But it will work with online data files also,but its not recommended.


DBVERIFY is invoked using dbv command.It should be called from ORACLE_HOME/bin directory.

To access help on DB_VERIFY type: 
dbv help=y




To perform a simple DBVIRIFY use below command.Output will be written to the dbv.log file.


>dbv file=/u01/oracle/product/10.2.0/oradata/orcl/users01.dbf logfile=dbv.log


Note that this is only a verification tool to get a idea about data files,whether they are corrupted or not.You'll have to follow other methods to recover corrupted data files.




Exmples:
dbv example of  a datafile with no corruption.
(Pages are data blocks)


DBVERIFY: Release 11.2.0.2.0 - Production on Tue Mar 13 15:41:47 2012
Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.
DBVERIFY - Verification starting : FILE = /..../a_01.dbf
DBVERIFY - Verification complete


Total Pages Examined         : 193648
Total Pages Processed (Data) : 43877
Total Pages Failing   (Data) : 0
Total Pages Processed (Index): 65406
Total Pages Failing   (Index): 0
Total Pages Processed (Other): 18833
Total Pages Processed (Seg)  : 0
Total Pages Failing   (Seg)  : 0
Total Pages Empty            : 65532
Total Pages Marked Corrupt   : 0
Total Pages Influx           : 0
Total Pages Encrypted        : 0
Highest block SCN            : 3753900931 (1388.3753900931)


dbv example of  a datafile with a corruption. 


DBVERIFY: Release 11.2.0.2.0 - Production on Tue Mar 13 15:32:33 2012


Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.


DBVERIFY - Verification starting : FILE = /..../a_02.dbf
Page 127845 is influx - most likely media corrupt
Corrupt block relative dba: 0x03c1f365 (file 15, block 127845)
Fractured block found during dbv:
Data in bad block:
 type: 6 format: 2 rdba: 0x03c1f365
 last change scn: 0x056c.dd2d2b24 seq: 0x1 flg: 0x06
 spare1: 0x0 spare2: 0x0 spare3: 0x0
 consistency value in tail: 0x00000000
 check value in block header: 0x21e0
 computed block checksum: 0x4ce


Page 127846 is marked corrupt
Corrupt block relative dba: 0x03c1f366 (file 15, block 127846)
Completely zero block found during dbv:


Page 127847 is marked corrupt
Corrupt block relative dba: 0x03c1f367 (file 15, block 127847)
Completely zero block found during dbv:


Page 127848 is marked corrupt
Corrupt block relative dba: 0x03c1f368 (file 15, block 127848)
Completely zero block found during dbv:
......
.....
....
...
Page 141294 is marked corrupt
Corrupt block relative dba: 0x03c227ee (file 15, block 141294)
Completely zero block found during dbv:


Page 141295 is marked corrupt
Corrupt block relative dba: 0x03c227ef (file 15, block 141295)
Completely zero block found during dbv:


Page 141296 is marked corrupt
Corrupt block relative dba: 0x03c227f0 (file 15, block 141296)
Completely zero block found during dbv:


DBVERIFY - Verification complete


Total Pages Examined         : 141296
Total Pages Processed (Data) : 60687
Total Pages Failing   (Data) : 0
Total Pages Processed (Index): 43333
Total Pages Failing   (Index): 0
Total Pages Processed (Other): 5417
Total Pages Processed (Seg)  : 0
Total Pages Failing   (Seg)  : 0
Total Pages Empty            : 18407
Total Pages Marked Corrupt   : 13452
Total Pages Influx           : 1
Total Pages Encrypted        : 0
Highest block SCN            : 3753900926 (1388.3753900926)

Partitioning and Formatting Second Hard Drive in Linux - (ext3)

by Jeff Hunter

http://www.idevelopment.info/data/Unix/Linux/LINUX_PartitioningandFormattingSecondHardDrive_ext3.shtml

Linux tar Command

The tar(tape archive) command bundles a bunch of files together and creates an archive on a tape, disk drive etc.


Simple way for creating a tar file.
Go to the relevant path.In our example go to the path where "myfolder" resides.So if I want to add files in myfolder to a tar file issue below command.It will create the tar file in /my location.


tar -cvf  /my/test.tar  myfolder


How to untar...
Go to the location where you want to untar the files/folder and issue below command.


tar -xvf  /my/test.tar


You can use below command to list the contents of a tar file to a log.


tar -tvf  test.tar  > temp/test.log




Options available with tar command:


c Create a new archive.
t List the contents of an archive.
x Extract the contents of an archive.
f The archive file name is given on the command line (required whenever the tar output is going to a file)
M The archive can span multiple floppies.
v Print verbose output (list file names as they are processed).
u Add files to the archive if they are newer than the copy in the tar file.
z Compress or decompress files automatically.