Troubleshooting
Problem
This technote will discuss how to increase connection limits so that the ITDS ldap server can support more than 4000 established TCP/IP concurrent connections,
Symptom
An error message similar to the following may appear in the ibmslapd.log file:
GLPSRV153W The server was not able to accept a requested client connection. The maximum capacity of 1009 has been reached. This error has occurred 78661 times."
Resolving The Problem
The error message may appear even though ulimits -a are set for the machine. Ulimits are operating system enforced. The newer releases of ITDS impose minimum ulimits to help prevent unnecessary cores. These minimum ulimits are configured in the ibmslapd.conf file.
In order to address this error, the solution is to increase the value of the ibm-slapdUlimitNofile in the ibmslapd.conf file. Setting this value will ensure that the server is started with the values that are set in the ibmslapd.conf file. In this case, changing the value from the default of 500 to a value of 4096 allows the number of simultaneous connections to be reached. The resulting message seen in the ibmslapd.log file should be similar to this:
03/30/10 11:59:54 GLPCTL122I Maximum Open Files soft ulimit for the process is 4096000 and the prescribed minimum is 4096000.
The settings in the ibmslapd.conf file can be managed using either the command line or the WebAdmin GUI tool. We do not recommend that you manually edit the ibmslapd.conf file. The operating system defaults and recommended minimums are provided in the "Enforcing Minimum Ulimits" section in the Administration Guide under the Server Administration --> Setting Server Properties sections. The section also provides directions on how to update the ibmslapd.conf file using the command line
or the WebAdmin tool.
http://publib.boulder.ibm.com/infocenter/tivihelp/v2r1/index.jsp?topic=/com.ibm.IBMDS.doc_6.2/admin_gd15.htm
It is also important to monitor the connection usage to get an idea of what the requirements are in the environment. The idsmonitor script is available to provide this function. This will allow the administrator to monitor the server to help determine what is reasonable usage or a client application leaking connections or not closing stale connections. This is a link to the technote which contains usage information for the idsmonitor script as well as a download for the script itself:
http://www-01.ibm.com/support/docview.wss?uid=swg21282708
Some platforms have hard limits on the operating system, and if you try to adjust the values in the ibmslapd.conf file, it can cause the server to start in configuration mode. This is a link for a technote on adjusting user process resource limits for the server process.
http://www-01.ibm.com/support/docview.wss?uid=swg21206894
Note that there is a known issue in ITDS 6.1 and ITDS 6.2 where this error message was erroneously reported. It was addressed via APAR IO10288 which was made available starting with ITDS 6.1.0.3 LA2 (6.1.0.24), and APAR IO10574 which was made available starting with ITDS 6.2.0.1 IF1 (6.2.0.4).
Related Information
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Document Information
Modified date:
16 June 2018
UID
swg21427541