How to check "bad page" efficiently?

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  • James Yang
    #1

    How to check "bad page" efficiently?

    "bad page", especially in table, is a risk for database maintenance.
    The particular access
    attempt for corrupt blocks may not occur often, and corrupt DB2 blocks
    are not recognized during a database backup, corrupt blocks can remain
    undetected in an UDB system for a long time.

    The potential solution is:

    1) Restore from a GOOD backup and rollforward (Recommended). The
    problem is backup normally is kept for 30 days so we must find the bad
    page in DB with retention period.

    2) db2dart /DDEL to dump the data, db2dart /IP to initialize the
    corrupt page, and then recreate the tabel, upload the data. The
    problem is data lost may happen and we need open an PMR.

    Anyway, we need check the bad page efficiently. My question is:

    * Which tool is recommended? db2dart or "inspect database" command?
    * Can we inspect a backup instead of the online database to avoid
    performance issue?
    * In general, how fast is it? Suppose it takes 10 hours for us to
    backup the database to Tivoli.

    P.S. It is a simple DBA task on Oracle platform.

    Any comment is appreciated.

    TIA
    James
    Tags: None
    • Mark A
      #2
      Re: How to check "bad page" efficiently?

      "James Yang" <James.YangGang @gmail.comwrote in message
      news:4efe63ca-2e6e-4e9d-9148-0966c9a79d15@b5 g2000pri.google groups.com...
      "bad page", especially in table, is a risk for database maintenance.
      The particular access
      attempt for corrupt blocks may not occur often, and corrupt DB2 blocks
      are not recognized during a database backup, corrupt blocks can remain
      undetected in an UDB system for a long time.
      >
      The potential solution is:
      >
      1) Restore from a GOOD backup and rollforward (Recommended). The
      problem is backup normally is kept for 30 days so we must find the bad
      page in DB with retention period.
      >
      2) db2dart /DDEL to dump the data, db2dart /IP to initialize the
      corrupt page, and then recreate the tabel, upload the data. The
      problem is data lost may happen and we need open an PMR.
      >
      Anyway, we need check the bad page efficiently. My question is:
      >
      * Which tool is recommended? db2dart or "inspect database" command?
      * Can we inspect a backup instead of the online database to avoid
      performance issue?
      * In general, how fast is it? Suppose it takes 10 hours for us to
      backup the database to Tivoli.
      >
      P.S. It is a simple DBA task on Oracle platform.
      >
      Any comment is appreciated.
      >
      TIA
      James
      The reason why it is a simple task on Oracle is that, unlike DB2, corrupted
      blocks are not unusual in Oracle. Extremely rare in DB2.


        Comment

        • James Yang
          #3
          Re: How to check &quot;bad page&quot; efficiently?

          Even it happens extremely rarely, we still need take it into account,
          don't we?

          So, how?

          >
          The reason why it is a simple task on Oracle is that, unlike DB2, corrupted
          blocks are not unusual in Oracle. Extremely rare in DB2.- Hide quoted text -
          >
          - Show quoted text -

            Comment

            • Mark A
              #4
              Re: How to check &quot;bad page&quot; efficiently?

              "Mark A" <nobody@nowhere .comwrote in message
              news:ABXKj.3269 6$r76.19021@big news8.bellsouth .net...
              The only time I have seen this happen in DB2 is when the server was
              experiencing serious disk errors (and the disk errors where also recorded
              in the db2idag.log file).
              Correction:

              s/b db2diag.log


                Comment

                • James Yang
                  #5
                  Re: How to check &quot;bad page&quot; efficiently?

                  Understood, thanks.

                    Comment

                    • john.enevoldson@pulsen.se
                      #6
                      Re: How to check &quot;bad page&quot; efficiently?

                      On 10 Apr, 07:29, James Yang <James.YangG... @gmail.comwrote :
                      Understood, thanks.
                      Hi,
                      We actually had this problem once which prompted us to include a
                      little automatic control against the db2diag.log each day:

                      if grep -i "bad page" /home/$1/sqllib/db2dump/db2diag.log
                      then mutt -s "$1 - bad page" dba@????????? < /PXX/scripts/prod/
                      badpage.txt
                      fi;

                      This mails out a warning to our dba mailbox. It gets run as part of
                      our daily housekeeping which amongst other things archives the
                      db2diag.log.

                      Regards,
                      John.


                        Comment

                        • Pierre StJ
                          #7
                          Re: How to check &quot;bad page&quot; efficiently?

                          On Apr 9, 12:09 am, James Yang <James.YangG... @gmail.comwrote :
                          Even it happens extremely rarely, we still need take it into account,
                          don't we?
                          >
                          So, how?
                          >
                          >
                          >
                          >
                          >
                          The reason why it is a simple task on Oracle is that, unlike DB2, corrupted
                          blocks are not unusual in Oracle. Extremely rare in DB2.- Hide quoted text -
                          >
                          - Show quoted text -- Hide quoted text -
                          >
                          - Show quoted text -
                          This is a late answer as I'd been away from the group for a while.
                          At DB2 V8.2 and up you can use the INSPECT command on the whole or any
                          part of the db. It runs concurrently with the db and is not very
                          intrusive.
                          DB2DART is an older command that will give you the bad page info but
                          it ihas to run with the db deactivated.
                          DB2CKBKP will also allow you to check a backup image for checkbits and
                          checksums that would show it in the image.

                          Understand that DB2 has an internal mechanism that will stop it from
                          retrieving a corrupted page.
                          The only way that I see the page being corrupted is if you have
                          hardware problems and/or applications that would have writtwen to the
                          file system holding the container of the tablespace that holds the
                          table. I really don't know or see how that could happen.
                          Regards, Pierre.

                            Comment

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