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RMS File and Disk Bad Block? (Invalid VBN)

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The Question is:

We have a corrupted file (We don4t konw how) and it can be repaired using
 analyze/disk/repair (It just says that some bad blocks there may be in that
 file). Is there another tool to repair this?. The output of analyze/rms is the
Check RMS File Integrity                     19-JAN-2004 10:10:01.95   Page 2
        Current Extent Start: 1003465, Blocks: 250008, Used: 61356, Next: 106482
        Default Extend Quantity: 63744
        Total Allocation: 250008
KEY DESCRIPTOR #0 (VBN 1, offset %X'0000')
        Next Key Descriptor VBN: 2, Offset: %X'0000'
        Index Area: 1, Level 1 Index Area: 1, Data Area: 0
        Root Level: 3
        Index Bucket Size: 12, Data Bucket Size: 12
        Root VBN: 1003381
        Key Flags:
                (0)  KEY$V_DUPKEYS    0
                (3)  KEY$V_IDX_COMPR  0
                (4)  KEY$V_INITIDX    0
                (6)  KEY$V_KEY_COMPR  1
                (7)  KEY$V_REC_COMPR  1
        Key Segments: 2
        Key Size: 19
        Minimum Record Size: 36
        Index Fill Quantity: 6144, Data Fill Quantity: 6144
        Segment Positions:      12    26
        Segment Sizes:           9    10
        Data Type: string
        Name: "juego+juegovta+sorteo+ticket"
        First Data Bucket VBN: 4
***  Attempt to read block with invalid VBN 796360.
Unrecoverable error encountered in structure of file.

The Answer is :

  All disks are subject to these errors, and as stated over in topic
  (6926), you must maintain disk BACKUPs, or utilize disk shadowing
  (mirroring), or other data archival procedures to recover from cases
  of block-level disk failures, or from catastrophic disk failures.
  You will typically want to replace the disk, and restore the BACKUP
  -- disk block errors were traditionally survivable, but bad blocks
  now do tend to be harbingers of impending disk failures.
  For information on the bad block handling available within OpenVMS,
  please see topic (6926) -- you can attempt to rewrite the entire
  disk to trigger bad block revectoring, but this may or may not
  resolve the underlying problem.  If this is not an isolated disk
  block failure, rewriting the entire volume will not likely be the
  appropriate approach.  Replace the disk.
  In all likelyhood, the RMS file with the reported bad block error is
  an innocent victim of the underlying bad block.
  For desperate cases (eg: BACKUP, what BACKUP?), you may be able to
  restore the data from the unaffected portions of the current file.
  This effort can be very time consuming, the outcome is unpredictable,
  and the effort involved can prove expensive.
  If you choose to attempt local restoration, create a small application
  which reads the file seqeuntially, writing out each record read into
  a new file.  Once the error is encountered, attempt reading by higher
  and higher key values until records are retrieved.  Write the record
  retrieved, and resume the sequential read and write processing.
  You might be able to locate potential key values for the intermediate
  processing from an older copy of the file, or from other parallel data
  stored on this or on another disk.
  You might also be able to use Record File Address (RFA) processing,
  using RFA operations within the damaged range to try to recover the
  You might also be able to use knowledge of the existing data records,
  for instance, to simply copy the records from the older (archived)
  version of file if it is known that the records affected by the disk
  corruption have not changed.
  There is an RMS_TUNING presentation available in the RMS_TOOLS area
  of the OpenVMS Freeware, and you can find an overview of an RMS
  Indexed file and its organization, and some ideas on patching the
  file back into operation.
  You will want to make a BACKUP/PHYSICAL of the disk before attempting
  recovery, of course.
  You can also choose to utilize HP Services to assist you in an attempt
  to recover the contents of this or other corrupted files -- if such
  recovery is possible, of course.

answer written or last revised on ( 20-JAN-2004 )

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