Critical buffer congestion

Technote (troubleshooting)


Problem(Abstract)

Upon activation of links, Communications Server runs into critical buffer shortages and memory allocation errors.

Symptom

2012-02-16 11:16:14 EST 256-14(0-10) E (PU)

Critical buffer congestion.

2012-02-16 11:17:40 EST 1-1(1-10) P (PU)

Memory allocation error. Size requested = 0x0140.


Cause

Available buffers ( buf_avail = ) was set to 10000, which is too low. Communications Server will set this dynamically at start up but, in this case, the value was over ridden with a snaadmin command and set too low.


Environment

AIX , Linux

Diagnosing the problem

The following display shows buf_use_status of congested and buf_avail of 10000.

query_buffer_availability display returns the following values:

reset_max_values = NO

buf_avail = 10000

buf_total_count = 79

buf_total_bytes = 67040

buf_rsrv_count = 0

buf_rsrv_bytes = 0

buf_res_use_count = 0

buf_res_use_bytes = 0

peak_usage = 10

peak_decay = 0

throttle_status = 30

buf_use_status = CONGESTED

max_buf_total_count = 82

max_buf_total_bytes = 99728

max_buf_rsrv_count = 0

max_buf_rsrv_bytes = 0

max_buf_res_use_count = 0

max_buf_res_use_bytes = 0

max_peak_usage = 0

max_throttle_status = 30

max_buf_use_status = CONGESTED

debug_param = <0000000000000000000000000000000000000000000000000000000000000000


Resolving the problem

A typical value that Communications Server will set is 2147483392. Communications Server will use 25% of available memory allocated at install for the buffer pool, up to 2GB. This value is set by Communications Server when the /etc/sna/snammlmt.exe is run at install. You can set this value yourself with the snaadmin set_buffer_availability,buf_avail=2147483392.

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Document information


More support for:

Communications Server for AIX
All

Software version:

5.0, 6.0, 6.1, 6.3, 6.3.1, 6.4, 6.4.0.1, 6.4.0.2, 6.4.0.3, 6.4.0.4, 7.0.0.0

Operating system(s):

AIX

Reference #:

1585855

Modified date:

2014-03-26

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