topic Re: Setting Kernel Parameters in Operating System - HP-UX

Setting Kernel Parameters

Ferber — Mon, 06 Aug 2007 11:04:19 GMT

Hi all,

I have an older HP C3600 Workstation.

I installed HP-UX 11.23 and did an patch inventory.

No I´m trying to set some kernel parameters.

I need to set msgseg=32767.

If I do so, HP-UX is not able to boot:

Very early in the boot process I receive the following message:

Can´t allocate message buffer

I searched the WEB, but was not able to find any useful info.

msgssz is set to 32767 and therewith msgssz * msgseg does not exceed the limit of 2^32-1
(manpage msgseg (5)).

Then I have to boot the former used kernel.

Is there anyone having an idea?

Re: Setting Kernel Parameters

Court Campbell — Mon, 06 Aug 2007 11:14:29 GMT

I would say that you need more memory.

Re: Setting Kernel Parameters

Don Morris_1 — Mon, 06 Aug 2007 11:58:44 GMT

Yup, note the warnings section of msgseg.5 (man msgseg or http://docs.hp.com/en/B2355-60103/msgseg.5.html):

A table of message segments is allocated in kernel memory at boot time. This memory is reserved whether or not it is used.

The memory requirement is the product the msgssz and msgseg tunables. Use care when setting these two tunables, as they can have a profound effect on memory utilization, due to the multiplicative effect.

(end quote)

So your setting means that the kernel needs at least 778773289 bytes (and may need more depending on page size rounding, padding, etc.). Since that's 742.696Mb, you're going to be very lucky to boot on a 1Gb system. Anything less I'd expect this failure... and it all depends on other kernel memory needs.

My recommendation would be:

Take a look at the output from your "good" kernel. There will be a set in the message buffer during boot that details the System, Kernel and User class information. The User Class will reflect the amount of memory consumed during boot by the kernel -- so the System Class physical memory minus the User Class physical memory tells you how much you need to boot that kernel [i.e. the kernel before your changes].

Take that amount, and subtract how much you'd like to devote to the tunables. I'd highly, highly recommend that you leave memory for running actual programs [because what's the point of booting a kernel with these tunable settings if you can't actually use it!]. In other words, determine how much of that memory you're willing to lose to increase your message tunables. Once you get that figure, determine the balance between the msgsiz and msgseg and set the tunables accordingly.

Re: Setting Kernel Parameters

Steven E. Protter — Mon, 06 Aug 2007 12:47:41 GMT

Shalom,

One of the things I do because Bill Hassell does it is remove most if not all formula's from my kernel.

Many of the formula's simply do not meet the real world test of having a relationship with reality.

So don't worry about formulas, take them out.

I was wondering if 11.23 is certified to run on a C3600 workstation. If not try 11.11.

HP is pretty serious about what the OS will run on and what it won't run on. The two OS's currently have the same end of life date.

All things being equal, I'd use 11.23 but the hardware may be the problem.

http://docs.hp.com to check OS certification.

SEP

Re: Setting Kernel Parameters

Steven Schweda — Mon, 06 Aug 2007 13:22:45 GMT

> I was wondering if 11.23 is certified to
> run on a C3600 workstation. [...]

According to the "HP-UX 11i v2 | Installation
and Upgrade Guide | June 2007":

NOTE
HP-UX 11i v2 is not supported on PA-RISC
Workstations. HP recommends that PA-RISC
Workstation customers use HP-UX 11i v1.
[...]

The v2 installation DVD did boot on my C3700,
while the v3 DVD did not. I installed v1,
but it wouldn't amaze me if v2 would work
(although not supported).

Coming from a VMS environment, where the
latest version runs on Alpha hardware much
older than these workstations, I find the
speed with which HP-UX abandons hardware to
be amazing and disappointing.