Memory usage on HP UX(Oracle 8.1.7 & Siebel)

My production database 8.1.7 is running on HPUx 11.11. The total physical memory on the box is 16 Gig. Around the peak time I'm always noticing about less than 100 meg free memory. My SGA is 7.4 Gig(Fixed 100kb, variable 1.0G, DB Buffer=6.4G, Redo=2M). Each process is using up approx 5-7 meg memory. SO during the peak time if there are approx 700 process my total memory usage is about 15G + and so I am left with about 100 meg. I also have 4 swap devices with 4 G each contributing 16G.

My question is ? Is there a way I can redistribute the memory usage or is it inevitable that we need more memory on the box ?? Can anyone give me a way to recalculate the memory usage for oracle and user processes ?

In terms of the shared pool, you could see if this can be reduced by taking a statspack report during peak uasage. Check the Memory Usage% bit of the Shared Pool Statistics section and see if this is significantly under used. Alternatively execute this:

SELECT pool, name, bytes / (1024*1024) FROM V$SGASTAT WHERE name = 'free memory'

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Originally posted by hacketta1

SELECT pool, name, bytes / (1024*1024) FROM V$SGASTAT WHERE name = 'free memory'

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I have check for the shared pool and it show about 50 - 100 meg free space which is OK. I am trying to find the right buffer cache size. Currently it is set to 6.4 G.

Also I am seeing a lot of inactive oracle processes but each one of them is using up around 7 meg memory. Guess that's how siebel is set up. Since there are about 1000 process(may be 200 of them inactive) uses a total of 7 G memory.

6.4G of buffer cache? how big is your database?

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Originally posted by marist89
6.4G of buffer cache? how big is your database?

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700GB

check your hit ratio and try to reduce the db buffer cache.

How did you find the memory usage of each oracle process? Using top? Top mis guides..

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Originally posted by nagarjuna
check your hit ratio ...

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Time for the asbetos underpants.

* ahem *

Hit ratio is a waste of times. Don't even think about it.

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Originally posted by slimdave
Hit ratio is a waste of times.

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In this case I don't agree - if the hit-ratio comes from a representative sample of activity and you monitor it as you reduce the buffer size, it should give an indication of when you've gone too far. End-user response time is of course a better statistic, but harder to measure.

(Hit-ratio is also a good indication of your success on "International Smack a Developer Day").

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Originally posted by nagarjuna
check your hit ratio and try to reduce the db buffer cache.

How did you find the memory usage of each oracle process? Using top? Top mis guides..

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I check the RSS(Resident Set Size) on glance for each process. It is suppose to give the total memory usage for each process. My Free Memory is going down to less than 60 meg during the peak hour(ususaly during 2:00pm - 3:00pm). I kill some of the most memory consuming porcesses to free up the memory. ANy advice on how to resolve the issue and not just ask for more memory. The DB buffer Cache was increased gradually to imporve performance. I guess I p'bly can decrese to some extent but not a whole lot.

The other thing is any connection from siebel evenif not active on oracle still uses the memory on the Box.

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Originally posted by DaPi
In this case I don't agree - if the hit-ratio comes from a representative sample of activity and you monitor it as you reduce the buffer size, it should give an indication of when you've gone too far. End-user response time is of course a better statistic, but harder to measure.

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I think that you missed out "... and if all of your SQL is perfectly tuned ..."