expand memory N4000

[A. Ardonne]

Hi,

I'm about to expand my 2gig memory to 4gig. I'm running HPUX 11.0 have 4 processors and have a oracle 8.1.7 database running.

Any considerations concerning kernel and/or oracle parameters?

I'm aware of the fact that my swapspace should be increased also, any advise to wich figure?

Thanks in advance

[G. Vrijhoeven]

Hi,

You might want to increase your swap space, so check maxswapchunks kernel parameter and disk space. Increase oracle 's SGA, decrease max_dbc_pct if set.


Gideon

[Stefan Farrelly]

You should increase swap to match RAM. ie. adding 2GB RAM, add a new secondary swap area of 2GB.

What is your dbc_mac_pct set to ? if say 20% which means 20% of 2GB = 400MB then increasing RAM to 4GB will double this to 20% of 4GB = 800MB which is a little high - ie. after a reboot you will notice not all the 2GB youve added is available for oracle as unix buffer cache has grabbed some, so this may need adjusting.

Last step is to increase your oracle SGA size - not by 2GB but try a bit smaller first, say 1GB and see how free memory goes first once under heavy user load before possibly adjusting more.

[RAC_1]

I can think of three things.

Increase swap space--add seconday swap space. Mostly in different vg.

Tune maxswapchunks kernel parametere-to reflect new RAM. Also tune dbc_max_pct parametere.

Last thing oracle sga. and shmmax kernel parametere.

[A. Ardonne]

Hi,

My dbc_max_pct is set to 5 which means the new figure will be 200mb. This seems to be reasonable?

I also notice that my allocated memory for oracle (ipcs -mbp) is 961mb while my kernel parameter maxdsiz_64bit is aprox 1073mb.
Until now this hasn't been a problem, but is there a %-rule for what it should be???

[Stefan Farrelly]

Yes, 200MB is reasonable for your new figure, you could even increase it a little (to around 400MB).

maxdsiz_64bit is the size of a single process - and with oracle no single process gets that large so no need to increase it. Basically you never want a single process to get as large in memory as you have physical RAM !