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ORA-600 [kcbzpbuf_1] ORA-600 [kcbzpb_1] Troubleshooting and workarounds (Doc ID 1560270.1)

Last updated on AUGUST 04, 2018

Applies to:

Oracle Database - Enterprise Edition - Version 8.0.5.0 to 12.2.0.1 [Release 8.0.5 to 12.2]
Information in this document applies to any platform.

Purpose

The purpose of this article is to describe the possible causes of ORA-600 [kcbzpbuf_1] and potential workarounds.

ORA-600 [kcbzpbuf_1] ORA-600 [kcbzpb_1] are produced by the DBWR background process because it encounters a corrupt block in the buffer cache (SGA Memory) before writing it to disk.  The error is produced to prevent DBWR from writing the corrupt block to DISK.  The block is not physically corrupt on disk but there is a possibility that it is logically corrupt or is free of corruptions on disk. Refer to <Note 840978.1> for Physical and Logical Block corruptions.

 

One example of this error is in the alert log is:

Hex dump of (file 7, block 297688234) in trace file <path>/trace/<sid>_dbw<n>_<pid>.trc
Corrupt block relative dba: 0x11be5caa (file 7, block 297688234)
Bad header found during preparing block for write
Data in bad block:
 type: <type#> format: <format> rdba: <relative dba>
 last change scn: <scn> seq: <seq#> flg: <flag value>
 spare1: <spare> spare2: <spare> spare3: <spare>
 consistency value in tail: <tail>
 check value in block header: <check value>
 block checksum disabled
Errors in file <trace file name>:
ORA-00600: internal error code, arguments: [kcbzpbuf_1], [<Corruption reason>], [<Calculate checksum flag>], [], [], [], [], [], [], [], [], []

 

 

The buffer cache block corruption can be caused by any of these sources:

  1. Memory hardware/OS problem that overwrote the block in the buffer cache (stray writes).
  2. The block is already logically corrupt on disk or modification to other logically corrupt blocks is causing stray writes.  Any modification to an already logically corrupt block may overwrite other blocks in the buffer cache and cause unexpected results.
  3. There is a block modification that is corrupting this block in the buffer cache.   Refer to <Note 337018.1> for known issues.

Troubleshooting Steps

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In this Document
Purpose
Troubleshooting Steps
 Enable checking parameters
 Identify other corrupt blocks on disk
 Additional parameter if checking does not detect a problem
References

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