tunining maxusers parameter

[MarkW_1]

HP unix 11i. Trying to increase maxusers per vendor request using sam. Getting this message:

The parameter modification(s) you have made have resulted in at least | ||
|| | one parameter evaluating to a value which is greater than its maximum | ||
|| | allowable value. Parameter "msgseg", currently set to "(MSGTQL*4)", | ||
|| | has evaluated to "77120", which is greater than its maximum allowable | ||
|| | value of "32767".

[A. Clay Stephenson · Accepted solution]

This is very typical of trying to use the pseudovalue (or macro) "maxusers" to adjust kernel parameters. There is no such tunable as maxusers; it is really only used in a number of formulae to tune a number of actual tunables at the same time. The problem is that often when only one of a set of values is needed to be changed, a herd of values are changed and not all are appropriate. You should contact the vendor and ask which specific tunables need to be set. In your case, you could probably just replace the message/semaphore related tunables from their current formula-based setting to numeric values but most experienced sys admins plug the numerical values in for almost everything. The formulae work well for typical systems with typical numbers of users and typical sets of applications. When you find one of those, let me know.

[Shine_5]

Hello,


The problem that lead to the above message is resolved by determining which restrictions the parameter has violated and how to resolve them. You can do a 'grep -i parameter_name /usr/conf/master.d/*' to see the interdendencies and mins/max values. This should help you determine what needs to be changed. For example...
1. Do a "grep -i msgseg /usr/conf/master.d/*" and you will see something like this /usr/conf/master.d/sysv-msg:*range msgmap<= (msgseg+2)
/usr/conf/master.d/sysv- msg:*range msgmax<=(msgssz*msgseg)
/usr/conf/master.d/sysv- msg:*range msgmnb<=(msgssz*msgseg)
/usr/conf/master.d/sysv- msg:*range msgseg<=32767
/usr/conf/master.d/sysv- msg:*range msgseg>=1
/usr/conf/master.d/sysv-msg:msgseg MSGSEG 2048


regards
Shine

[Jeff_Traigle]

It looks like your kernel has been modified from the defaults already. (msgtql is default 40 and maxseg is default 2048... static values.) Since you're getting the error trying to increase maxusers, I'd guess your msgtql value was changed to a formula that relies on it, either directly or indirectly through another kernel parameter. Change the msgseg formula to allow the larger value... trace where the dependence on maxusers is in msgtql and change the formula there... change msgseg to appropriately large static value as indicated by the message you received... several possibilities. Pick your poison. (You might look for guidance from your vendor to see what, if any, impact such changes would have on their application... though increasing values of things doesn't typically affect them... just eats up more memory for the kernel to use.)