> in AIX 5.3, are the number of semaphores in the kernel settings for the
> OS manually configurable?
> and if
> our environment is informix version 10 on aix 5.3 and we received a
> crash and were told that the failure was caused by the engine not
> having enough semaphores in the kernel settings - but alas, we were not
> told any more details than that so far.

According to the documentation, these parameters 'do not require tuning
because they are dynamically adjusted'. See

The parameter in question would be semmni.

There are operating system limits, see

There is no command I know that will show you the value of semmni,
but the following C program does the trick:


int main(int argc, char **argv) {
struct ipc_limits out;

if (vmgetinfo(&out, IPC_LIMITS, sizeof(out))) {
perror("vmgetinfo() unexpectedly failed");
return 1;

printf("semmni = %llu\n", out.semmni);
return 0;

Laurenz Albe