Joel,
DUDE probably is overkill for one block, but it depends on the value
of the data. If you think about the cost of a DBA, an IT manager, a
business manager, and a business analyst all working 4-8 hours
trying to diagnose and clean up the mess caused by the data lost in
a small number of blocks, then the $1000-$5000 spent on DUDE becomes
a bargain. Kurt Van Meerbeeck (http://www.ora600.be) is the creator
of DUDE and Dan Fink and I are the US contacts for Kurt.
There is the ALTER SYSTEM DUMP DATAFILE command, with the following
syntax...
SQL> alter system dump datafile '<file-name>'
| <file#> block [ <block#>
| block min <beginning-block#> block max
<ending-block#> ];
where...
- "<file-name>" is the name of the Oracle datafile
- "<file#>" is the FILE_ID of the Oracle datafile
- "<block#>" is the database block number
- "<beginning-block#>" is the starting block number
within the datafile
- "<ending-block#>" is the ending block number
within the datafile
The output will be dumped to an Oracle trace file within the
USER_DUMP_DEST directory. Example ALTER SYSTEM DUMP DATAFILE
commands include...
- alter system dump datafile
'+DATA_DG/datafile/PROD/system_1_123456.dbf' block 32;
- alter system dump datafile 3932 block min 100 block max
200;
The first command dumps one block from the indicated ASM datafile in
the SYSTEM tablespace. The second command dumps 101 blocks from
datafile #3932.
Of course, I long for the grand old days of the DEC VMS "dump"
command, but on UNIX/Linux you might consider something like the
following...
$ dd if=<file-name> bs=<db-block-size>
seek=<beginning-block#> count=<#blocks>
| od -cx > <output-filename>
where...
- "<file-name>" is the name of the Oracle datafile
- "<db-block-size>" is the size of the Oracle
database blocks in that tablespace
- "<beginning-block#>" is the starting block number
within the datafile
- "<#blocks>" is the number of blocks you wish to
dump
So, the UNIX/Linux "dd" command extracts the block(s) from the
datafile and the UNIX/Linux "od" (a.k.a. "octal dump") command
translates the stream into "ASCII character" (i.e. "-c" flag) and
hexadecimal (i.e. "-x" flag).
Hope this helps...
Tim Gorman
consultant -> Evergreen Database Technologies, Inc.
postal => P.O. Box 630791, Highlands Ranch CO 80163-0791
website => http://www.EvDBT.com/
email => Tim@xxxxxxxxx
mobile => +1-303-885-4526
fax => +1-303-484-3608
Lost Data? => http://www.ora600.be/ for info about DUDE...
On 7/29/2010 8:46 AM, Joel.Patterson@xxxxxxxxxxx wrote:
When
all hope fails – block recover,
dbms_repair, etc. and before you enable skipping corrupt
blocks, is there
some utility that can show me what is in the block?
Something
like a hex reader, but since it
is only one block, (and we are probably going to be
getting rid of that data
anyway), the method should be free. (For instance, I
think dude (possible
spelling) is something that could work, but for one block
it would be
overkill).
Even
if it is not free, you could let me
know. I probably won’t get it, but the information would
be
useful, and the question has been raised.
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