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SAP Buffers can be reset with below commands :

1.    /$SYNC        - Resets the buffers of the application server
2.    /$CUA          - Resets the CUA buffer of the application server
3.    /$TAB          - Resets the TABLE buffers of the application server
4.    /$NAM          - Resets the nametab buffer of the application server
5.    /$DYN        - Resets the screen buffer of the application server
6.    /$ESM          - Resets the Exp./ Imp. Shared Memory Buffer of the application server
7.    /$PXA          - Resets the Program (PXA) Buffer of the application server.

 **Please Note : Resetting of the buffers could change the performance of the entire system.

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4 Comments

  1. Thanks for the useful transaction details. 

  2. Recommendation:
    If you do not know what you are doing or what you want to achieve... please rather consider a controlled restart !!!

    Resetting buffers can however be the right trick to do if your SAP kernel or applications does not behave correctly and you need/want to avoid a restart of your system.
    There should however be no doubt that a controlled restart is a safer way, though often can be more inconvenient.
    Unnecessary usage of resetting buffers (or even restarts) can be a "quick-fix" to many problems, though does not really deal with the core/root problem which is then likely to occur again. Unless you understand the root cause and impact of your handling it is therefore difficult to give an ultimate answer to what you should do.

    Is it safe to reset buffers?
    *** Please note that resetting buffers can have serious side-effects - also other than Performance loss

    Example: Buffered Number Ranges
    Worst case scenario you could get a "hole" in your number range. This might seem harmless from a technical perspective - and often is, but in rare cases it could lead to legal issues.
    If it is safe to reset a buffer or not would therefore depend on what the buffer is used for, as well as how SAP and the applications handle these...

    Decision to reset or not
    Performance impact might be an acceptable alternative rather than a restart of the system, though a controlled restart of the system would be safer way to deal with issues.
    However, restarting a system with 24x7 could be unacceptable as well...

    You must have a general idea about "Why" you should reset the buffer(s) and preferably be selective related to the buffer you are resetting.

    You should (at least) consider:
     - do you know which buffer is causing you trouble (avoid using /$SYNC)?
     - impact of potential side-effects (is this a production system?)
     - Is it likely that resetting the buffer(s) will solve your problem (has the system been working ok before?)
     - do you have extra application servers (ref. buffer synchronization)?
     - is the system heavy loaded (users/processes)?
     - is there any other alternatives (take out of Logon/RFC group and wait until freed up... consider restart)

  3. Hi,

    /$OBJ resets the shared buffer. This is also documented in SAP Note 100923.

    1. !!!! ### ATENTION ### !!!!

      Resetting buffers can significantly change the performance of the entire system for a long time. 

      It should therefore only be used where there is a good reason to do so.

      (You should run the command where you normally run the transaction)

      /$SYNC - Resets the buffers of the application server
      /$CUA - Resets the CUA buffer of the application server
      /$TAB - Resets the TABLE buffers of the application server
      /$NAM - Resets the nametab buffer of the application server
      /$DYN - Resets the screen buffer of the application server
      /$ESM - Resets the Exp./ Imp. Shared Memory Buffer of the application server
      /$PXA - Resets the Program (PXA) Buffer of the application server
      /$TAB RSADMIN refreshes buffers for specific tables e.g. RSADMIN
      /$TAB refreshes all table buffers + the program buffer
      /$SYNC refreshes all table buffers, except the program buffer

      SU53 and click authorization values —> Reset User Buffer.

      SU01 -> environment -> mass changes -> reset all user buffers

      Executing transaction PFUD or running program RHAUTUPD_NEW

      se38 and program: RSUSR405