Question

need to corrupt a block in windows for oracle testing puposes

Asked by: it-rex

for testing puposes we need to corrupt few blocks in windows to test recovering them in Unix you can use the dd coomand to do that but how to do that in windows??

thanks

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Asked On
2009-07-03 at 06:50:09ID24542330
Tags

windows unix oracle corrupt block

Topic

Oracle Database

Participating Experts
2
Points
500
Comments
6

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Answers

 

by: schwertnerPosted on 2009-07-03 at 06:58:20ID: 24772366

Create   own tablespace
create tablespace x datafile 'X01.DBF' size 10m;
create table x(A number,b varchar2(10)) tablespace x;
insert into x values(1,'CATS');
insert into x values(1,'DOGS');
Now i can see CATSin the file. This means i can edit a few
characters here or there that is in that block.
If you are using windows, it will not allow you to open the file with
another program like word.
So make a copy of the file.
 
copy the file using this
alter tablespace x offline
alter tablespace x online)


Another source:

Disclaimer severe damage may result. Make sure you have anything
necessary backed up. Do not do this on a production system!

The best advice would be to open a tar with oracle and get them to
supply info. But they won't do that ( at least easily ) when the
subject is how to corrupt a block.

Then proceed carefully and do some queries to identify what block you
want to wack!

The following script will ( perhaps ) work on a cooked file system.

*** Script supplied by oracle in the advanced rman class ...

> more corrupt.sh
#!/bin/ksh
FILE=${1:?'Parameter 1 should be set to file name'}
BLOCK=${2:?'Parameter 2 should be set to the block to be corrupted'}
dd of=$FILE bs=8192 conv=notrunc oseek=$BLOCK < CORRUPT
EOF

You may have to do something a little differently on a raw partition
and perhaps adjust the seek value ( from what block oracle thinks it is
) ( varies by os and logical volume manager setup )

> more bad_block.sh
#!/bin/ksh
dd if=/home/oracle/badb13.dd of=/dev/vs_4/r_(fill_in_raw_partion)_.dbf
bs=8192 seek=13 count=1


 

by: mrjoltcolaPosted on 2009-07-03 at 08:03:15ID: 24772774

Either install a hex capable editor or install Cygwin, which has UNIX utilities in it like dd

UltraEdit is one such that I use.

 

by: mrjoltcolaPosted on 2009-07-03 at 08:42:50ID: 24773027

Try this, Perl should be on your system already if you have Oracle.

perl corrupt.pl <filename> <blocknum>

It will write the garbage string below to the complete block you specify, based on 8k blocksize.

#!/usr/bin/perl
 
die unless scalar @ARGV > 1;
 
my $file = shift;
my $block = shift;
 
print "Writing garbage to $file block $block\n";
 
open FILE, ">$file" or die "$!";
 
binmode FILE;
 
seek FILE, 8192 * $block, 0;
my $s = "0123456789ABCDEF";
for(my $i = 0; $i < 8192/length($s); $i++) {
   print FILE $s;
}
                                              
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by: it-rexPosted on 2009-07-04 at 20:44:28ID: 24778768

Guys are these methods for windows

 

by: mrjoltcolaPosted on 2009-07-05 at 15:25:00ID: 24781500

This method will work on any platform, it is Perl. The windows Perl will ignore the "#!/usr/bin/perl" portion and take the .pl as an extension to signify it is a Perl program. If the Oracle Perl does not handle it (which it should) then you can use ActivePerl

I wrote and tested on Windows before I posted.

 

by: schwertnerPosted on 2009-07-06 at 03:30:43ID: 24783843

You can ftp the tablespace file in character mode to other server and ftp it back.
it will be corrupted.
Also every common editor like notepad will edit and change some characters in the file.
Do not get involved in exotic methods.

20120131-EE-VQP-002

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