about tune kernel parameter

[hongjing_zhang]

I want to tune SHMMAX to 2G ,but when I make kernel then reboot. the machine reboot and reboot. please help me!

[Satish Y]

Hi,

How much is ur memory size?.
Because the maximum size of the shared memory is approximately 33% of total RAM size.
If you are using 10.20 tne maximumsize of shmmax can be approx 1 GB,
u can gain more shmmax by applying some patches.

Increasing shared memory on an S800 running HP-UX 10.20 go through the following URL:

http://us-support.external.hp.com/cki/bin/doc.pl/sid=53abb6901bbd43430e/screen=ckiDisplayDocument?docId=200000024645549

For ur problem, bring the machine to single user mode and then rebiuld the kernel with less value of shmmax and the apply patches as said above.

hope it helps

Cheers...
Satish.

[Brian M Rawlings]

A couple of points...

1> More info, please. It is unlikely that we will be much help to you without knowing some details like your current memory size, OS version, and other such useful data. Hopefully the info provided to you already will help, but, as a general rule, please give us something to go on.

2> I don't know how you modified your kernel, but you may find it useful to do in SAM, which has some built-in safeguards and rules. It will often tell you when a size can't be used, and why (what its dependencies are). It can be a pain, but it can keep you from making mistakes like this. It is also not infallible, you still need some common sense.

3> When you reboot in single user mode, go to /stand and cp vmunix.prev to vmunix.good, or something like that. You only get one saved copy of the known good working kernel, so save it before you make further changes. If you want to boot back up in your previous good state, 'cp vmunix vmunix.bad' (not really necessary, but I never delete until all is said and done). Then 'cp vmunix.prev vmunix', and reboot (shutdown -ry 0).

At least this way you'll have a good, working kernel for your experimentation. Hope SAM gives you better guidance than your assumptions, and good luck.

Regards, --bmr