Re: RMAN fails because of corrupt block in seemingly free space in SYSTEM

  • From: Riyaj Shamsudeen <rshamsud@xxxxxxxxxxxx>
  • To: "Bobak, Mark" <Mark.Bobak@xxxxxxxxxxxxxxx>
  • Date: Wed, 03 Jan 2007 13:32:55 -0600

Can you please dump those 10 blocks and confirm those blocks are indeed corrupted ? Not falsely reported as corrupt by rman ? I am not pre-judging rman, but just wanted to be sure.

If all these 10 blocks are corrupted, then I wouldn't think that skgfrsiz issue (as Robert Freeman pointed ) would have caused this corruption. From the bug reports, it looks like only the last block will be corrupted. Further, as per your posting, this block is at 512M of 2000M.

Can you check with sysadmin to see what is so special about this 512M boundary ? May be AIX has some kind of extent or partition management ? That would give out some clues.

Also, do you use concurrent IO in AIX ? If yes, do you have fix for APAR IY70031 installed ? Refer:

If there are no blocks after the 512M boundary, then you could potentially resize down and resize it back. That should remove this corruption.

If not, you could use transportable tablespace method. Still, it's probably better to open a case with Oracle support and IBM, at this point, so that you could avoid this problem in


Riyaj Shamsudeen

Bobak, Mark wrote:
I've seen similar looking corruptions on a few of my databases as well. I never did get to the bottom of the problem. However, in terms of solving the problem and moving on, you ought to be able to set MAXCORRUPT greater than then number of corrupt blocks you have, backup the datafile(s) affected, and then, restore datafile(s) from backup. Since they were corrupt on backup, Oracle will format the block at restore time. As long as the block is not part of any segment, that's ok. Note that if any corrupted block is part of any segment, the above is a bad idea. -Mark

*Mark J. Bobak*

*Senior Oracle Architect*

*P**ro**Q**uest Information & Learning*

There is nothing so useless as doing efficiently that which shouldn’t be done at all. –Peter F. Drucker, 1909-2005

*From:* oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] *On Behalf Of *Uldis.Pavuls@xxxxxxxxxxxxxxx
*Sent:* Wednesday, January 03, 2007 12:35 PM
*To:* rshamsud@xxxxxxxxxxxx
*Cc:* oracledba.williams@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
*Subject:* RE: RMAN fails because of corrupt block in seemingly free space in SYSTEM

it's quite possible the OS partition has been resized, i do not know, my role is rather consulting at need. I'm not on-site, it makes things a bit difficult. However, I did not find any tracs of resizing in the alert-log, at least not for the system tablespace (they certainly had had some difficulties with undo resizing, however). In fact there is account for 10 blocks in row corrupted in similar way, all fractured and with CORRUPTION_CHANGE#=0, rman just falls back on the first, although, it seems, have recorded other piece of 9 blocks - next to the first one - in v_$database_block_corruption.Citation: select T.NAME "T-space", D.NAME "Filename", C."FILE#" "FileId", C."BLOCK#" "BlockId", C.BLOCKS,
where C."FILE#" = D."FILE#" and D."TS#" = T."TS#" order by 1, 2, 3, 4 ;
<Output as CSV>:
<end of output>
All datafiles are locally managed and on raw devices (under VLM on AIX 5.3, so they are partitions in fact); there should be my first post (2 January, 2007) with a bit more info. Thanks for the idea of use of transportable tablespaces, it didn't occur to me. I'll certainly consider that. I was rather thinking about shrinking that file and then re-expanding it, that should clear the corruption on success - how do you think? It would be faster if succeeded. Altogether on the second thought CORRUPTION_CHANGE#=0 should mean media corruption, so your approach may be safer in long run.
Best regards,

Uldis Pavuls
DBA, TietoEnator
41 Lacplesa Str., Riga, Latvia, LV 1011
phone +371 7 286 660, fax +371  7 771 313
mailto:Uldis.Pavuls@xxxxxxxxxxxxxxx <>

    -----Original Message-----
    *From:* oracle-l-bounce@xxxxxxxxxxxxx
    [mailto:oracle-l-bounce@xxxxxxxxxxxxx] *On Behalf Of *Riyaj Shamsudeen
    *Sent:* otrdiena, 2007. gada 2. janvārī 23:50
    *To:* Pavuls Uldis
    *Cc:* oracledba.williams@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
    *Subject:* Re: RMAN fails because of corrupt block in seemingly
    free space in SYSTEM


        rman does not backup "never used" blocks, not "free" blocks.
    It is quite possible that this block was previously used and rman
    will back this block also.

        Looking at the following lines, clearly even rdba in the block
    is corrupted. Many other fields are corrupted too. Weird thing is
    that block is corrupted exactly at 65535 block, which happened to
    be a binary power of 16. Was this raw device extended using OS
    tools in the past  ? If yes, from what size ? What is your
    db_block_size ?

    Corrupt block relative dba: 0x0040ffff (file 1, block 65535)
    Fractured block found during backing up datafile
    Data in bad block -
     type: 0 format: 2 rdba: 0x0000ffff
     last change scn: 0x0000.00000000 seq: 0x1 flg: 0x05
     consistency value in tail: 0x0074117a
     check value in block header: 0xfef9, computed block checksum: 0x9
     spare1: 0x0, spare2: 0x0, spare3: 0x0

        Can you dump the block itself  and print trace lines ? alter
    system dump datafile 1 block min 65535 block max 65535

        Also, in your SQL, can you select block_id too ?

    from SYS.DBA_FREE_SPACE where FILE_ID=1
    and BLOCK_ID <=65535  and (BLOCK_ID+BLOCKS-1)>=65535;

        Is system locally managed or dictionary managed, in your
    database ?
I am not sure why Oracle support would say that it is okay to
    have corrupt block, that too in a system tablespace. If I were
    you, I would be looking at creating a new database and
    transporting non-system tablespaces from current database to new
    database, urgently.

    Riyaj Shamsudeen

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