DOCUMENT:Q246590 16-MAY-2002 [sna] TITLE :COMTI Cannot Use All Available LU6.2 Sessions PRODUCT :Microsoft SNA Server PROD/VER:WINDOWS:1.0 SP1,4.0,4.0 SP1,4.0 SP2 OPER/SYS: KEYWORDS: ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft SNA Server, versions 4.0, 4.0 SP1, 4.0 SP2 - Microsoft COM Transaction Integrator for CICS and IMS, versions 1.0 SP1, 4.0 SP2 ------------------------------------------------------------------------------- SYMPTOMS ======== When a COM Transaction Integrator for CICS and IMS (COMTI) component attempts to establish multiple APPC conversations to a host transaction program (TP) over a given APPC triplet (Local LU, Remote LU, and Mode), COMTI may be unable to use all of the available sessions that were negotiated during the Change Number of Sessions (CNOS) exchange. For example, if a maximum parallel session limit of 6 is negotiated for a particular LU triplet, COMTI may only see 3 of the sessions. It will never attempt to use the remaining available sessions, regardless of the load or volume of data that may be arriving from upper-layer applications. CAUSE ===== By design, COMTI APPC conversations can only be established over LU6.2 contention winner (conwinner) sessions. In many cases, the conwinner-session limit negotiated during the CNOS exchange is less than the total parallel sessions supported for the mode. Only conwinner sessions are visible to COMTI. RESOLUTION ========== A supported feature that modifies the product's default behavior is now available from Microsoft, but it is only intended to modify the behavior described in this article and should be applied only to systems having a specific need for it. This feature may receive additional testing at a later time, to further ensure product quality. Therefore, if you are not severely affected by the lack of this feature, Microsoft recommends that you wait for the next Microsoft SNA Server version 4.0 service pack 3 that contains this feature. To obtain this feature immediately, contact Microsoft Product Support Services. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web: http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS The English version of this feature should have the following file attributes or later: +---------------------------------+ | File name | Date | Time | +---------------------------------+ | xxxxxxxx.xxx | xx/xx/xx | xx:xx | +---------------------------------+ NOTE: Date and time information will be provided as soon as it becomes available. NOTE: Because of file dependencies, the most recent fix that contains the above files may also contain additional files. STATUS ====== Microsoft has confirmed this to be a problem in the Microsoft products that are listed at the beginning of this article. MORE INFORMATION ================ When COMTI formulates an MC_ALLOCATE request to initiate a conversation to the remote TP, it sets the return control (rtn_ctl) attribute to AP_WHEN_CONWINNER_ALLOC to specifically ask for a conwinner session. Considering that COMTI is the initiator of all transactions, making use of conwinner sessions is the most optimal choice when performance is a concern. There is no bidding overhead incurred for conversation startup. When all conwinner sessions are in use, available contention loser (conloser) sessions will not be useable by COMTI. Contention loser sessions are also known as partner contention winner sessions. The feature update mentioned in this article simply allows COMTI to make use of all available sessions regardless of whether they are conwinners or conlosers. This has been achieved by setting the MC_ALLOCATE rtn_ctl attribute to AP_WHEN_SESSION_ALLOCATED. By default, SNA Server exhausts all cowinner sessions first before resorting to the contention losers. For additional information, click the article number below to view the article in the Microsoft Knowledge Base: Q196391 Factors Affecting COMTI Performance Additional query words: ====================================================================== Keywords : Technology : kbAudDeveloper kbSNAServSearch kbCOMTISearch kbCOMTI100SP1 kbCOMTI400SP2 kbSNAServ400 kbSNAServ400SP1 kbSNAServ400SP2 kbComSearch Version : WINDOWS:1.0 SP1,4.0,4.0 SP1,4.0 SP2 ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2002.