Microsoft KB Archive/268127

= TN3270 LUs must be pooled across multiple nodes or connections =

Article ID: 268127

Article Last Modified on 12/4/2007

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APPLIES TO


 * Microsoft Host Integration Server 2004 Standard Edition
 * Microsoft Host Integration Server 2000 Standard Edition
 * Microsoft SNA Server 4.0
 * Microsoft SNA Server 3.0 Service Pack 2
 * Microsoft SNA Server 3.0 Service Pack 3
 * Microsoft SNA Server 3.0 Service Pack 4
 * Microsoft SNA Server 4.0
 * Microsoft SNA Server 4.0 Service Pack 1
 * Microsoft SNA Server 4.0 Service Pack 2
 * Microsoft SNA Server 4.0 Service Pack 3

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This article was previously published under Q268127



SYMPTOMS
3270 clients that are requesting a session through a TN3270 server may fail with a blank screen or error message when SNA Server or Host Integration Server is configured by using multiple connections or multiple nodes.

See the &quot;More Information&quot; section of this article for configuration environments in which these problems may occur.



CAUSE
When a session request comes in, the TN3270 server searches for the first LU name that matches the request (for example, 3278-2-E). When the TN3270 server finds this, it specifies the LUA name in RUI_INIT, which causes an OPEN SSCP request to be sent to the SNA Server service (node). At this point, the node tries to use that resource because it is informed to use that specific LUA LU. The TN3270 server does not validate whether the LUA LU is available or inactive. It is not the application's (TN3270 server in this case) responsibility to do this. If the requested LUA LU is inactive, the problems described in the &quot;Symptoms&quot; section occur.

When you use LUA Pools, the problem does not occur because the RUI_INIT request contains the Pool name. In this case, the node is responsible for finding an available LUA LU in the pool for use.



RESOLUTION
To resolve this problem, do the following:
 * 1) Delete the individual LUA LUs from the TN3270 server.
 * 2) Assign the LUA LUs from each node or connection to a LUA Pool.
 * 3) Assign the LUA Pool to the TN3270 server.



STATUS
This behavior is by design.



MORE INFORMATION
In both of the following examples, LUA Pools are not being used. Only individual LUA LUs are assigned to the TN3270 server.

Example 1: Using multi-node support
SNA Server or Host Integration Server is configured by using multi-node support (multiple SNA services on one server), and the last node (for example, SNA Server 02) that was added or configured is stopped or paused. When a session is requested, a blank screen is displayed, even though sessions are available on the other (original) SNA Server or Host Integration Server node.

In addition to the blank screen, the following error message is displayed in the lower left corner of the screen if you are using the 3270 applet that is included in SNA Server or Host Integration Server 2000:

[TN3270-36]: Error - An error occurred during device type/name processing.

NOTE: Other third-party emulators may report a different message.

If you review the Application log in the Event Viewer during this time, the following two events are posted:

Event 1955 - Source: SNA RUI Application

RUI_INIT failed for LU , primary_rc = 4f0, secondary_rc = 0

Event 602 - Source: TN3270 Server

TN3270(E) session terminated normally with client at   using LU 

Example 2: Multiple Connections across one or more servers
SNA Server or Host Integration Server is configured by using multiple connections on one SNA Server, or multiple connections on other SNA Servers in the same SNA Server or Host Integration Server subdomain. If the last connection that was added or configured is stopped, the following error message is displayed if you are using the 3270 applet that is included in SNA Server or Host Integration Server, even though other sessions are available on other connections:

TN3270E Service Message 523

The data link is activating for LU 

You may continue to wait, or terminate your session.

NOTE: Other third-party emulators may report a different message.

Additional query words: HIS 2000 HIS2004

Keywords: kbhowto KB268127

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