MK_KERNEL or SAM - this is the question

[Tom Dineen_2]

Do you use MK_KERNEL to build the kernel when you change a kernel-tunable ?

Can someone share their notes on using MK_KERNEL ??

[Robert-Jan Goossens · Accepted solution]

Hi Tom,

Check this thread,

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=106979

HTH,
Robert-Jan

[Bill Hassell]

mk_kernel works just fine as long as you remember all the other steps! Like any major build process, you need to keep an old copy of the kernel under a common name, the /stand/system file, etc. SAM does all of this for you and is a lot easier to modify kernel parameters because of the online help for each parameter (the only source for this info inside HP-UX).

[Fabio Ettore]

Hi Tom,

it is a good question.
My opinion: the best way to change a kernel-tunable parameter is SAM.

My reasons: for change a kernel parameter and rebuild it there are some commands, not only mk_kernel.
You know, talking about kernel operations/actions/commands (everything) are very delicate!
SAM works very well about kernel operations and also GUI to change a kernel parameter is very friendly.
I would tell you to use mk_kernel only when there are problems about SAM (e.g. SAM doesn't run or GUI has problems).

Anyway I don't think SAM is the best tool for other operations. Just two examples: network configuration and LVM.
I always suggest to use commandline for network configuration and LVM operations.


Conclusion:
In my opinion SAM should be used for kernel changes, I would tell only for that.
Usually I prefer to work by commandline.

Best regards,
Ettore

[John Carr_2]

SAM is HP recommended way to rebuild kernel and helps avoid missing anything for the novice. alwaysn make sure you have a backup of the kernel when building from the command line.

:-) John.

[Geoff Wild]

I use SAM to compile a new kernel - cause it looks after things that you may forget to do.

That being said, here's a doc on HP:

http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/5187-2216/5187-2216_top.html&con=/hpux/onlinedocs/5187-2216/00/00/36-con.html&toc=/hpux/onlinedocs/5187-2216/00/00/36-toc.html&searchterms=hpux%7ckernel%7crebuild&queryid=20040511-065706

Rgds...Geoff

[Bart Paulusse]

I use SAM. I've done the hard way as well, but remembering all the steps is critical... and since I'm lazy I prefer SAM.

[Hemanth Gurunath Basrur]

Hello Tom,

Even I prefer to use SAM. I have also rebuilt the kernel using mk_kernel. I referred the mk_kernel manpage and completed the process of building the kernel.

Regards,
Hemanth

[Victor Fridyev]

Hi,

IMHO, you may use mk_kernel, with all backups, naturally, when you are sure that the changes are valid, i.e. if you checked them with SAM on a test computer and have to repeat the changes somewhere else.
Additionally mk_kernel is irreplaceble if you want to create a procedure for computers upgrade.

[John Dvorchak]

I usually use SAM for any kernel tuning. Now that being said I just completed tuning the kernel on three systems and used mk_kernel because I wanted them all the same and there were numerous tunables to deal with. So after the system_prep step I used vi to cut and paste the tuned parameters and that worked faster for me. Here are the steps I used:

1. cd /stand/build
2. /usr/lbin/sysadm/system_prep -v -s system (creates system file)
3. vi system ---- (modify list)
4. mk_kernel -s system -- (create vmunix_test file)
5. mv /stand/vmunix /stand/vmunix.prev
6. mv /stand/system /stand/system.prev
7. mv /stand/build/system /stand/system
8. kmupdate /stand/build/vmunix_test
9. reboot

Good luck,
John

[Siddhartha M]

Hi

mk_kernel should really be used as a last resort.If you can change a kernel parameter using SAM,then go for it.
However there will be instances(eg maxdsiz_64bit) when kernel
tuning through SAM is a no-go.

Please go through the attached note.
This provides an outline to carry out a kernel change via mk_kernel.

Substitute and with your site specific parameters.

-Siddhartha

[Bharat Katkar]

Do you use MK_KERNEL to build the kernel when you change a kernel-tunable ?

NO .. NO.. NO..

SAM SAM SAM

[A. Clay Stephenson]

My view is that one should use SAM for kernel changes (or disk changes, user changes, ...) ONLY when one has mastered the underlying steps involved in the operation. Yes, learning is tedious, but if all one knows is SAM then when the train runs off the track, one's toolbox is rather limited. SAM is a good tool but understanding the underlying processes is much more important. When one knows all the steps then one can make an intelligent, informed choice about the better method --- for the particular job at that particular time.