PM59395: FTP CHECKPOINT RECORDS NOT FLUSHED TO CHECKPOINT DATASET

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• FTP is configured to write checkpoint records at CHKPTINT record
  intervals.  FTP does not force checkpoint records to be written
  to the file.  It allows the default behavior of the I/O routines
  to determine when records are committed to disk.  If the FTP job
  is canceled or abends prior to a record being written to disk,
  the checkpoint data set can be empty.  The transfer will not be
  able to be resumed.  FTP should write records to disk when
  checkpointing is active.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of the IBM Communications Server   *
  *                 for z/OS Version 1 Release(s) 11, 12 and 13  *
  *                 IP: FTP                                      *
  ****************************************************************
  * PROBLEM DESCRIPTION: The FTP checkpoint file's markers are   *
  *                      buffered in storage before being        *
  *                      written to the external storage media.  *
  *                      This can cause a longer restart time.   *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  FTP uses the IBM XL C/C++ fwrite() facility to write its
  checkpoint markers. fwrite() buffers the markers in storage
  until its buffer is full and then writes them to the external
  file. If the checkpointed file transfer is cancelled by system
  operator command before the fwrite() buffer is full or an
  fclose() is issued, the buffered markers will not be written to
  the external file. This will cause the FTP RESTART subcommand
  to retransmit data that has already been transferred.
  +-------------------------------------------------------------+
  + Please check our Communications Server for OS/390 homepages +
  + for common networking tips and fixes.  The URL for these    +
  + homepages can be found in Informational APAR II11334.       +
  +-------------------------------------------------------------+
  

Problem conclusion

• A new FTP client FTP.DATA statement CHKPTFLUSH has been added
  to specify whether FTP should force z/OS to flush checkpoint
  information to storage media as each record is written, or
  allow z/OS to determine when checkpoints should be flushed from
  volatile storage to storage media.
  
  The following documentation updates will be made.
  
  IBM Communications Server:
  IP Configuration Reference
  SC318776
  
  Add the following FTP.DATA data set statements
  
  CHKPTFLUSH (FTP client) statement
  
  When FTP saves checkpoint information in the check point file or
  data set, z/OS might buffer the records in volatile storage
  instead of writing the data to storage media immediately. Use
  the CHKPTFLUSH statement to specify whether FTP should force
  z/OS to flush checkpoint information to storage media as each
  record is written, or allow z/OS to determine when checkpoints
  should be flushed from volatile storage to storage media.
  
  Guideline:
  If you allow z/OS to buffer check point records, and you
  configure a large check point interval, and your operator
  cancels a file transfer while check pointing is active, you
  could lose most or all of the check point data. This is because
  z/OS has no chance to flush buffered data to storage media when
  the FTP job is cancelled. If you lose most or all of the check
  point data, you cannot restart the file transfer from the point
  where it was interrupted. For long running file transfers, this
  is very inefficient. Code CHKPTFLUSH TRUE if this is a problem
  at your installation.
  
  Syntax
  
  |--- CHKPTFLUSH---FALSE---|
  |-------------------------|------
  |--- CHKPTFLUSH---FALSE---|
                 |---TRUE---|
  
  Parameters
  
       FALSE
            z/OS is allowed to buffer checkpoint records in
            in volatile storage when FTP saves them. z/OS will
            choose when to flush buffered records to storage
            media. This is the default value.
       TRUE
            Checkpoint records are flushed to storage media as
            soon as FTP saves them.
  
  
  Example
       CHKPTFLUSH TRUE  ; Checkpoint records are flushed to
                        ; storage media as soon as FTP saves them.
  
  
  Related topics
         . CHKPTINT (FTP client and server) statement
         . CHKPTPREFIX (FTP client)  statement
  ================================================================
  
  IBM Communications Server:
  IP User's Guide and Commands
  SC318780
  
  Add the following to the LOCSITE Subcommands
  
  Add the following 2 lines into the format chart:
  
      CHKPTFLUSH
      NOCHKPTFLUSH
  
  And add the following descriptions:
  
  CHKPTFLUSH
      whether flush every checkpoint from buffer to storage media
      as soon as FTP saves them.
  
      CHKPTFLUSH      ; Checkpoint records are flushed to storage
                      ; media as soon as FTP saves them.
      NOCHKPTFLUSH    ; z/OS is allowed to buffer checkpoint
                      ; records in volatile storage when FTP saves
                      ; them. z/OS will choose when to flush
                      ; buffered records to storage media.
                      ; This is the default value.
  ================================================================
  
  IBM Communications Server:
  Quick Reference
  SX750124
  
  Chapter 2. TSO commands
  
  LOCSITE subcommand
  
  Add CHKPTFLUSH alphabetically to the syntax diagram for the
  locsite subcommand.
  
      CHKPTFLUSH
      NOCHKPTFLUSH
  ================================================================
  
  * Cross Reference between External and Internal Names
  EZAFTPSM (FTPDMSG )  EZAFTPSM (FTPDMSG )  EZAFTPSM (FTPDMSG )
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UK78083 UK78084 UK78085

Modules/Macros

• EZAFTPAC EZAFTPCG EZAFTPCL EZAFTPCP EZAFTPCY
  EZAFTPDM EZAFTPEA EZAFTPEH EZAFTPEP EZAFTPGL EZAFTPGM EZAFTPMK
  EZAFTPM9 EZAFTPRM EZAFTPRX EZAFTPSM EZAFTPSR EZAFTPTO
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R1B0 PSY UK78083

     UP12/05/30 P F205

• R1C0 PSY UK78084

     UP12/05/30 P F205

• R1D0 PSY UK78085

     UP12/05/30 P F205

Fix is available

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