topic Re: Kernel Modification with Memory Added in Operating System - HP-UX

Kernel Modification with Memory Added

Steven Chen_1 — Tue, 23 Apr 2002 12:44:42 GMT

Hello,

I have 1G memory on K260 of hpux11i running Oracle 8i now. 1G more memory will be added and therefore Oracle SGA will be modified too.

I would like to know that on hpux level if any kernel parameters need to to modified so that 2G memory can be used (to overcome kernel fence?).

It will be very appreciated if someone can help.

I would attach a concurrent kernel configuration file for your inspection. First thing jump to my mind is the maxdsiz.

Thanks a lot.

Steven

Re: Kernel Modification with Memory Added

Jeff Schussele — Tue, 23 Apr 2002 12:57:48 GMT

Hi Steven,

I don't see any kernel params that MUST be changed, but my caveat would be to make sure that swap *at least* is on a one-to-one ratio with memory.
And you already have swap_mem_on at 1 so that's alright.
You'll need to watch the system - particularly Oracle performance & the max*siz & shm* usage to determine if you'll need to tune these after the upgrade & Oracle SGA mod.
Also watch mem/swap usage closely.
Use sar over a broad time range across all normal Oracle usage scenarios if possible.

Rgds,
Jeff

Re: Kernel Modification with Memory Added

Bill McNAMARA_1 — Tue, 23 Apr 2002 12:58:06 GMT

http://docs.hp.com/servlets/iknow/iKtypeB?INFO_TYPE=how&Action=upgrading&Item=K-Class+memory&INFO_TYPE_CHANGED=false&Topic_Area=Hardware+Installation+and+Configuration&Sub_Topic=K-Class+Server&MODE_A=SLAVE&MODE_I=MASTER

or ask iknow at:
http://docs.hp.com/servlets/iknow/iKtypeA

Later,
Bill

Re: Kernel Modification with Memory Added

John Payne_2 — Tue, 23 Apr 2002 13:05:18 GMT

Steven,

One thing to remember when adding memory is that dbc_max_pct and dbc_min_pct are percentages of memory. By adding another 1GB increment, if you do not change these values, your file system buffer cache will go from a 50MB-150MB range to a 100MB-300MB range. That is not necessarily bad, but if you do not want your buffer cache that big for an Oracle database machine, you need to lower the percentages.

It becomes a bigger problem when people have bigger percentages and add more memory...

Hope it helps.

John

Re: Kernel Modification with Memory Added

nancy rippey — Tue, 23 Apr 2002 13:07:46 GMT

You will probably want to increase your swap if you are adding memory. Along with this you would want to increase maxswapchunks.
maxswapchunks

maxswapchuncks
This (in conjunction with some other parameters) sets the maximum amount of swap space configurable on the system. Maxswapchunks should be set to support sufficient swap space to accommodate all swap anticipated. Also remember, swap space, once configured, is made available for paging (at boot) by specifying it in the file /etc/fstab (/etc/checklist on 9.X). The maximum swap space limit calculated in bytes is: (maxswapchunks * swchunk * DEV_BSIZE). We recommend this parameter be set to 4096.

Hope this helps

nancy

Re: Kernel Modification with Memory Added

Steven Chen_1 — Tue, 23 Apr 2002 15:04:57 GMT

Thanks all for the help.

So we don't have to do anything on maxdsiz, semmni, semmns, shmmni, shmmax....?

Steven