2617932 - Sporadic IPHR s_corruptdiskblkhdrexception errors in multiplex system after CN rollbacks - SAP IQ 16

• Affects only SAP IQ multiplex systems where a large number of rollback operations happen in the CN Coordinator node.
  
  
• There must be at least one MPX writer node updating disk blocks at the same time within a SQL Cursor opened with HOLD option.
  
  
• Sporadic IPHR errors across multiple physical block numbers (PBNs) start to get reported in the iqmsg file.
  
  

  I. 02/19 20:15:20. 0000006018 {945} main Bufman: Incorrect page header read; from slib/s_trycatch.cxx:2954 into buffer 2513a8c8

  I. 02/19 20:15:20. 0000006018 {945} expected: btype=14,pbn=318134644,txn=99509992,sp=1,nlb=16,npb=16,iscmp=0,uid=3385997,blk=318134644,mn=1006,upmn=1006,flgs=0x80000008
  
  

  I. 02/19 20:15:20. 0000006018 There was an s_buf::Read() error during s_bufman::Find().

  I. 02/19 20:15:20. 0000006018 The following exception is from GetBlockmapEntryInfo

  I. 02/19 20:15:20. 0000006018 Blockmap Member Variables for 4b9a29d758

  I. 02/19 20:15:20. 0000006018 From slib/s_dpidx.cxx:594
  
  

  I. 02/19 20:15:20. 0000006018 Exception Thrown from slib/s_blockmap.cxx:7094, Err# 0, tid 936 origtid 936

  I. 02/19 20:15:20. 0000006018 O/S Err#: 0, ErrID: 2100 (s_corruptdiskblkhdrexception); SQLCode: -1009039, SQLState: 'QSA39', Severity: 14

  I. 02/19 20:15:20. 0000006018 [20060]: main Bufman: An error was detected on a database page. You may have a damaged index. For additional information, please check your IQ message file or run sp_iqcheckdb.

   -- (slib/s_blockmap.cxx 7094)

• This can lead to DBCC corruptions reported by sp_iqcheckdb leaving damaged table objects that need to be rebuilt.

• A variety transaction failures and stacktraces can start to appear, either Non-Fatal or server aborts.

•  SAP IQ 16.x multiplex systems on all platforms

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