NUMFDSERVERS configuration parameter

For network connections on UNIX, use the NUMFDSERVERS configuration parameter to specify the maximum number of poll threads to handle network connections migrating between HCL Informix® virtual processors (VPs).

Specifying NUMFDSERVERS information is useful if Informix has a high rate of new connect and disconnect requests or if you find a high amount of contention between network shared file (NSF) locks. You can use the onstat -g ath command to display information about all threads. This information includes a status, such as mutex wait nsf.lock, which indicates that you have a significant amount of NSF lock contention.

onconfig.std value
NUMFDSERVERS 4 (Only the first 4 poll threads of each nettype are involved in managing the connection migrations.)
1 - 50

The actual number depends on the number of poll threads, which you specify in the NETTYPE configuration parameter.

takes effect
After you edit your onconfig file and restart the database server.


The specified value of NUMFDSERVERS has no effect on shared-memory (SHM) connections.

If you use the NUMFDSERVERS configuration parameter, also review, and if necessary, change the number of poll threads in the NETTYPE configuration parameter. For example, if you have multiple CPU VPs and poll threads and this results in NSF locking, you can increase NUMFDSERVERS and poll threads to reduce NSF lock contention.

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