PM52007: FTP SERVER RETURNS "450 DATASET <DSNAME> IS ALLOCATED TO ANOTHER JOB AND IS UNAVAILABLE FOR STOU COMMAND"

APAR status

• Closed as fixed if next.

Error description

• When transferring a file using SUnique, the FTP server returns
  the response
  
    450 Data set USER1.UPDATE.TXT3 is allocated to another job and
    is unavailable for STOU command
  
  Though it is possible for a file transfer using SUnique to fail,
  it should not fail because a dataset is in use by another job.
  This is caused by a timing window in which multiple jobs may be
  attempting to use the STOU simultaneously.
  

Local fix

• Add automation or an FTP EXIT that will randomize the
  dataset name which will be allocated by the FTP server.  For
  example, a portion of a timestamp can be appended to the
  name to reduce the likelihood of two processes attempting to
  simultaneously allocate the same dataset name.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of the IBM Communications Server   *
  *                 for z/OS Version 1 Release(s) 12 and 13      *
  *                 IP: FTP                                      *
  ****************************************************************
  * PROBLEM DESCRIPTION: When two FTP clients transfer a data    *
  *                      set by PUT command with SUNIQUE         *
  *                      asynchronously, on some rare occasions  *
  *                      one client gets a 450 error. The error  *
  *                      indicates that Data set <data set name> *
  *                      is allocated to another job and is      *
  *                      unavailable for the STOU command. The   *
  *                      transfer fails.                         *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  FTP has a SUNIQUE command to make sure you can get a unique
  data set name for PUT command (STOU). FTP uses function
  find_unique_file() to check whether the data set name exists
  and to get a unique data set name. When two clients try to get
  a unique name from find_unique_file() at the same time, they
  will get the same name. The first client to create the data set
  will not have a problem, but the second client attempting to
  create the data set will receive a 450 error showing that the
  data set is in use by another job.
  +-------------------------------------------------------------+
  + 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

Temporary fix

Comments

• This APAR is being closed FIN (Fixed If Next) with concurrence
  from the submitting customer. This means that a fix to this
  APAR is expected to be delivered from IBM in a release (if any)
  to be available within the next 24 months.
  
  The following change(s) will be included
  in z/OS Communications Server V2R1:
  The FTP client will look for a unique name again if the STOU
  command returns a message showing that the data set is allocated
  to another job. The maximal retrying time is 10. After retrying
  10 times, if the client still can not get the unique name, the
  transfer will fail and a new message will be reported to show
  that the STOU command can not create a unique file name.
  

APAR Information

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

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

Fix information

Applicable component levels

• R1C0 PSN

     UP

• R1D0 PSN

     UP