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Memory requirement for oracle 8i

RAJESH GANGADHARAN
Regular Advisor

Memory requirement for oracle 8i

Hi
we are going to upgrade our servers, this time we need to calculate the actual amount of memory used for each oracle database instances. Can any one suggest how much RAM is required for 1 GB database.

Thanks in advance.
Rajesh G
Let the choices you make today be the choices you can live with tomorrow.
7 REPLIES
Joaquin Gil de Vergara
Respected Contributor

Re: Memory requirement for oracle 8i

have a look to this web

http://www.hporaclectc.com
Teach is the best way to learn
RAJESH GANGADHARAN
Regular Advisor

Re: Memory requirement for oracle 8i

Hi
Thanks for the update, but I am not able to acess the site

-Rajesh G
Let the choices you make today be the choices you can live with tomorrow.
Joaquin Gil de Vergara
Respected Contributor

Re: Memory requirement for oracle 8i

it works

I probe it

Nombre: www.hporaclectc.com
Address: 195.2.165.29

Teach is the best way to learn
RAJESH GANGADHARAN
Regular Advisor

Re: Memory requirement for oracle 8i

Hi
I am able to open the site, But I don't have a user id and password to login. It is not allowing me to create a new user id.
Let the choices you make today be the choices you can live with tomorrow.
harry d brown jr
Honored Contributor

Re: Memory requirement for oracle 8i


You have to be either an HP partner, an HP employee or an Oracle employee to access that site.

As to your question: it depends.

(1) How much hardware resources does your server have?

(2) What OS release are you running?

(3) How big do you want the SGA to be?

(4) How much growth in the DB do you expect?

(5) How many users/processes will be "attached" to the database?

(6) What kind of IO activity is expected?

(7) What is the disk sub-system?

(8) Who won the baseball world series?


live free or die
harry
Live Free or Die
Yogeeraj_1
Honored Contributor

Re: Memory requirement for oracle 8i

hi,

the amount of ram will depend on the number of users per instance and which mode you are operating (normally dedicated is OK).

You should size your SGA. Nothing to do with the size of the database!

RAM should be double that of the SGA, which is a good general rule, but not necessarily bulletproof.

As for gauging the amount of memory used per user connection, in a dedicated server mode you can generally assume that each user will consume 1.5 to 2 mb of memory, depending on the value for sort_area_size. Bear in mind that sort_area_size, if set to 1mb, will not stay at 1mb if there is not an active sort occurring. SORT_AREA_RETAIN_SIZE can be used to determine the actual continual value per user process.

There is no way to assume memory usage short of assuming that all connected users are maximizing the sort_area_size, therefore multiple sort area by the maximum number of concurrent sessions. That is the best means of estimating sort memory usage.

Thus, with a sort_area_size of 4mb (aprox.), you need to assume that all users can simultaneously start a large sort and therefore use 5.5 mb of memory (based on a 1.5 mb stack size).

Also, you can monitor sorts using the view v$sesstat (sorts are statistic 64 in 8.1.6), and over a period of time come to conclusions about the maximum sort usage during peak usage. However, if you need to make allowances, always assume a maximum usage.

Generally if you want to do the initial rough estimate on higher side,you can consider atleast 4-5 Mb memory per session(Oracle user)+ Required memory for oracle database and OS.
And for every one GB RAM you can consider 1 CPU.
(So e.g. if you are going to have 200 oracle users you can think of keeping 1GB RAM for Oracle Processes + 4 GB (SGA estimate) + OS (1GB)
So total is 6 GB RAM and 6CPU this is just a rough estimate and test this.)

If you want detail estimate you will have to do lot of calculations on
No. Of concurrent users connected to the oracle database.
No. Of transactions expected
Type of workload you are going to have and when that load will be there on the system.
No of batch processes

After calculating all this you can compare your results with the bechmark and select the CPU and Memory. This can be best close estimate.


Hope this helps!

Regards
Yogeeraj
[Source metalink]
No person was ever honoured for what he received. Honour has been the reward for what he gave (clavin coolidge)
Steven E. Protter
Exalted Contributor

Re: Memory requirement for oracle 8i

256 MB for 8.1.7 Release 3. For performance reasons, you need more.

Try this utility if you have more memory than that. It helps with the kernel and shared memory segments, semaphores, et al.

Ignore the memory error warning.
Steven E Protter
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