topic Question about Maxuser kernel param in Operating System - HP-UX

Question about Maxuser kernel param

Vito Sarducci — Fri, 30 Nov 2001 15:14:06 GMT

The vendor for the the application we have wants us to change the maxuser value from 32 to 400? What ramifications might this have on my system? Im not sure, but it sounds like their shooting in the dark on this one?

Please advise?

Vito

Re: Question about Maxuser kernel param

James R. Ferguson — Fri, 30 Nov 2001 15:17:10 GMT

Hi:

This is not uncommon. See here for an explanation of the use of this parameter:

http://docs.hp.com/hpux/onlinedocs/os/KCparam.MaxUsers.html

Regards!

...JRF...

Re: Question about Maxuser kernel param

Marco Paganini — Fri, 30 Nov 2001 15:18:31 GMT

Hello Vito,

"Maxusers" is not a kernel parameter per se. It actually serves as a base to adjust the values of nproc, ncallout, ninode and nfile.

If I were you, I'd ask him specifically for values for these parameters. With that information (and knowing how their system operates) you'll be able to decide if they need to be changed or not.

Regards,
Paga

Re: Question about Maxuser kernel param

S.K. Chan — Fri, 30 Nov 2001 15:18:33 GMT

"
When there is a need to increase overall system resources, the kernel parameter 'maxusers' can be used. It is a simple way to increase
several values at once, while retaining the correct relationships
between the parameters.

'maxusers' influences system resource allocation and does not control
the actual number of users on the system. The limit placed on the
number of users depends on the HP-UX user license purchased. You can
check the user license with "uname -a".

By itself, 'maxusers' does not determine the size of any structures in
the kernel. However, the default value of many other system parameters
depend on 'maxusers'.

The 'maxusers' parameter defines the macro 'MAXUSERS' and this macro
determines the size of system tables. Rather than varying each
configurable parameter individually, the system sets certain parameters
using a formula, based on the maximum number of expected users.

For example, the formula for 'nproc', the total number of processes that
can exist simultaneously on the system, is determined with this formula:

20 + 8 * MAXUSERS

So, if you increase the maximum number of users on your system, you can
adjust the general system resources in proportion to the new number, by
just changing the 'maxusers' value.

The importance of tuning 'maxusers' rather than individual parameters
becomes more evident the larger the system grows. Using 'maxusers'
takes care of dependencies, and other easily overlooked parameters, that
should be kept in line with system and kernel structure growth. The
parameter 'nclist', the number of 'cblocks' the system can use, is a
good example of a lesser known parameter that is kept in line via
'maxusers'.