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II11712: READ FIRST/FIX LIST: OS/390 AND Z/OS PERFORMANCE AND TUNING (APAR 3 OF 3: SEE APARS II11710 AND II11711)

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APAR status

  • Closed as canceled.

Error description

  • !!! NO LONGER MAINTAINED AS OF 3/26/08 !!!
    REFERENCE THE FOLLOWING URL FOR INFORMATION
    REGARDING z/OS COMMUNICATIONS SERVER PERFORMANCE:
    http://www.ibm.com/support/docview.wss?rs=852&uid=swg27005524
    .
    .
    KEYWORDS: TCPIPINFO PERFORMANCEX
    5655HAL00 R340 R350 R50A OS390IP TCPIP TCP/IP
    TCP/IP Performance Checklist
    ============================
    Here is a quick summary of a performance checklist, which may
    help in confirming performance settings for your environment.
    * MVS dispatching priority of TCP/IP, FTP or other servers:
      Recommendation: Set TCPIP equal to VTAM or 1 lower than VTAM.
      For other started tasks such as FTP, ADSM: slightly lower than
      TCPIP task.
    * Make sure client/server TCP Window size is set to allowed
      maximum.  Recommendation: Set the TCP window size on MVS to
      the allowed maximum by setting TCPRCVBUFRSIZE to 32K or larger
      and, if client workstation permits, use 65535 as the client
      window size. If the installation is storage constrained,
      however, use the default TCPRCVBUFRSIZE of 16K.
    **********NOTE WINDOWS NT USERS************
    Windows NT defaults send window size to 8K(8192) update parm
    DefaultSendWindow in order to increase the send window.
    Users of other TCPIP stacks need to refer to Vendor to
    determine how to increase send window size.
    
    
    
    .
      Note: RFC 1323 which supports larger than 64K-1 TCP window
      size is available in V2R7.
    .
    * Make sure client and server MTU/packet size are equal.  Follow
      the recommendations given in the PROFILE.TCPIP section of this
      information APAR.
    * 3172: Make sure Delay timer and Max. response length are set
      correctly for each LAN adapter:
      Recommendation:  Delay Timer = 10 ms,
                       Max. response length = 500 bytes
    * 2216: Make sure Blk timer and Ack length are set correctly
      for each LCS or MPC+ definition:
      Recommendation:  Blk  Timer = 5 ms,
                       Ack Length = 10 bytes
    * FTP: Use large data set blocksizes on MVS.  Recommendation:
      Data set blocksize = 1/2 DASD track.  Follow the
      recommendations discussed in the FTP DATA section of this
      information APAR.
    * Sockets: Use large msg sizes (> 1 KB) for better performance.
    * PTF's: Make sure you have latest TCP/IP Performance PTF's.  We
      continually improve performance of OS/390 releases and it is
      recommended to keep track of PSP buckets for important PTFs.
    * Make sure TCP/IP and all other traces are turned off for
      optimal performance. Trace activity does create an extra
      processing overhead.
    * CS/39 Performance Web Page References:
      http://www.software.ibm.com/network/commserver/library
            /whitepapers/csos390.html
      http://www.software.ibm.com/enetwork/commserver/library
            /whitepapers/white_csos390ip.html
    .
    CAPACITY PLANNING
    *****************
    The information provided here will provide you the methodology
    for capacity planning for  Telnet and FTP.
    .
    CAPACITY PLANNING (TELNET TN3270):
    In order to determine the capacity planning requirements, one
    needs to determine the CPU cost of performing a transaction of
    interest on a specific machine type.
    For example, we have used the Telnet TN3270 workload where
    100 bytes of data is sent from Telnet client to Echo application
    running on OS/390 Telnet TN3270 Server and 800 bytes of data
    is sent by Echo application as a reply to Telnet client.
    From our benchmarks we have derived CPU cost in terms of
    milliseconds per Telnet TN3270 transaction using IBM
    9672-RX6 (4 CP LPAR).
    .
        - 0.59 msec/tran  (For number of users  4,000 to 16,000)
        - 0.65 msec/tran  (For number of users 16,001 to 32,000)
        - 0.71 msec/tran  (For number of users 32,001 to 64,000)
    .
    Above CPU numbers include TCPIP, VTAM and Echo application.
    For example, we want to determine the capacity planning
    requirements for 4000 users, each doing 6 transactions per user
    per minute on a IBM 9672-RX6 (4 CP LPAR).
    .
    Total CPU Requirements:
      # trans/user  x # users x CPU secs/tran      CPU secs
      ---------------------------------------   =  ---------
                 # of Elap secs                    Elap secs
    .
     Example:   CS/390 R5,  4000 users,   6 tr/min/user
    .
      6 tr/u x 4000u x 0.00059 CPU secs/tr            cpu sec
      ------------------------------------- =  0.236   --------
                60  elap. sec                          elap sec
    .
      If the CPU secs/Elap sec ratio is greater than one, more than
      one CPU processor capacity would be required to drive the
      workload.
    .
    Total CPU Utilization:
    .
      CPU secs/Elap Sec
      -----------------  *  100 %   =  CPU Util %
       # of processors
    .
       # of processors:  4 ( This will be equal to number of
                        390 processors used for the LPAR)
    .
      Example:   Therefore, Percentage of CPU utilization on Four CP
      LPAR to drive 6 tran/user/minute for 4,000 users will be
    .
      0.236 CPU secs/Elap sec
      -----------------------  *  100 %  =  5.9 %
           4 processors
    .
      Thus, the total CPU requirement for 4000 TN3270 users would
      require 5.9 % of a four processor IBM 9672-RX6 machine.
      LSPR can be used to adjust for other processors types.
      Consult your IBM marketing representative or systems engineer
      to get the correct relationship in processing power between
      the different IBM processors.
    .
    FTP Capacity Planning:
    =====================
    The methodology for FTP capacity planning is very similar to
    Telnet. The key difference is that one needs to determine the
    average cost for transferring a Kbytes of data on a given
    setup, i.e., machine type, channel attached device, type of
    workstation, type of transfer, etc.. One can derive the
    CPU cost using the selected setup by repeating FTP transfers
    of large files. CPU cost per Kbyte must include TCPIP, VTAM and
    FTP address space usage.
    .
    Total (TCPIP+VTAM+FTP) CPU Requirements for FTP transfer:
    .
      Max KB         CPU  secs        CPU secs
      ---------   *  ---------   =   ----------
      Elap secs         KB           Elap  secs
    .
    For example, if we are interested in driving aggregate effective
    FTP throughput of 10000 KBytes/Second for transferring data from
    workstations to MVS using 2216 as the Channel attached device
    and FDDI as the LAN media on ES9672-RX5 3 CP LPAR:  From our FTP
    measurements of binary PUT, 20 Mbytes file transfer, we have
    determined that CPU cost per Kbyte is 0.0000347 CPU seconds.
    .
       10000 KB       .0000347          .347    CPU secs
      ---------   *  ------------   =          ----------
      Elap secs         KB                     Elap  secs
    .
    If the CPU secs/Elap sec ratio is 1 or greater, one would need
    more than one processor capacity to drive the desired
    throughput.
    .
    MVS TCP/IP CPU Utilization:
    .
      CPU secs/Elap Sec
      -----------------  *  100 %  =  CPU Util %
       # of processors
    .
      # of processors:  4 ( This will be equal to number of
                        390 processors used for the LPAR)
    .
     Example: For our example we are using ES9672-RX5 4 processor
     LPAR.  Therefore, Total CPU utilization will be
    .
       0.347 CPU secs/Elap sec
      -----------------------   *   100 %   = 8.675 %
           4 processor
    .
    Thus, Total CPU  (TCPIP+VTAM+FTP) requirements for
    driving 10000 Kbytes/second throughput on ES9672-RX5 (4 CP LPAR)
    will be 8.675 %.
    If you are using different type of mainframe, but keeping the
    other setup same, you can use the LSPR information to adjust
    the above CPU utilization. Consult your IBM marketing
    representative or systems engineer to get the correct
    relationship in processing power between the different IBM
    processors.  The above methodology can be used for deriving the
    capacity planning for different types of workload
    

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

APAR Information

  • APAR number

    II11712

  • Reported component name

    PA LIB INFO ITE

  • Reported component ID

    INFOPALIB

  • Reported release

    001

  • Status

    CLOSED CAN

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    1999-02-23

  • Closed date

    1999-03-08

  • Last modified date

    2009-02-18

  • 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



Document information

More support for: z/OS family

Software version: 001

Operating system(s): MVS, OS/390, VSE/ESA, z/OS, z/VM

Reference #: II11712

Modified date: 18 February 2009