Buffer Pool Error 685 Printing Two Large Jobs Simultaneously

The information in this article applies to:

• Microsoft SNA Server for Windows NT, versions 3.0 SP1

SYMPTOMS

When SNA Server attempts to process two large print jobs (approximately 700 pages), the SNA 3270 Emulator logs an event 685, indicating that a failure to extend a buffer pool occurred. The affected component is terminated and both print jobs fail.

   ID 685 Event Details

   An attempt was made to extend a buffer pool, but the related pool had
   reached its maximum size. The affected component is terminating, and an
   audit of the buffer pools just before termination is attached

   Pool               Free     Alloced      Max
   Trusted Hdr         122        157     100000
   Trusted Elts         50        112     500000
   Non-Trusted Hdrs      1       2993       3000
   Non-Trusted Elts     87       3142      10000

   Comname      Pid      Trusted      Hdrs       Elts
   SNABASE    00000072      Y            0          0
   MNGAGENT   000000A7      Y            8         11
   MNGCLI     000000C1      Y           12         36
   SNASERVR   00000068      Y            5          5
   SNADLC2    00000106      Y            5          5
   SNADLC1    000000F3      Y            5          5
   WIN3270    000000F0      N            0          0
   SNAPRINT   0000005A      N         2992       3055

   EXPLANATION
   This error is almost always due to either an SNA component (including
   possibly an emulator) losing buffers or a slow emulator (or RUI
   application) using a session without pacing.

   ACTION
   Contact your support personnel.

CAUSE

The print server will occasionally produce an extra credit message. Normally this would not cause a problem. The print server would cope with the extra message. However, in the case of a very large job, the print server never has time to catch up with the extra messages. The input queue increases until the buffer limit is reached (3,000 outstanding messages).

RESOLUTION

Defer sending credit messages until the print server is capable of processing the message immediately, so that the message is not put back on the input queue.

STATUS

Microsoft has confirmed this to be a problem in SNA Server 3.0 Service Pack 1 (SP1). This problem was corrected in the latest SNA Server version 3.0 U.S. Service Pack. For information on obtaining this Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K