Hello

If you refer to "linuxatemyram.com/index.html" or "//mandrivausers.org/index.php?/topic/30923-whats-eating-my-memory"
according to that contexts the "cached" and "buffers" values of free command are the memory that kernel uses for I/O so when our applications need more memory the kernel reduce buffer and cache to release memory for applications

and "linuxatemyram.com/index.html" says
Too see how much ram is free to use for your applications, run free -m and look at the row that says "-/+ buffers/cache" in the column that says "free". That is your answer in megabytes
Now I think it's not right because I have a PC with 2G RAM and I have installed Linux and Oracle database in it

I should say in Oracle database we can define memory of database and I've set the memory of my database (SGA+PGA) 2G , equal to My RAM size

Now before I start my database I run free -m commend and result is :

Code:
   $ free -m             
              total           used       free      shared    buffers     cached

Mem :         1743             574         1169        0        24        310
-/+ buffers/chache:            238         1504
Swap:         4596              0          4596
After I start my database (It uses 2G memory) I run free command again , the result is :

Code:
   $ free -m             
              total           used       free      shared    buffers     cached

Mem :         1743             860         883        0        25        544
-/+ buffers/chache:            290         1453
Swap:         4596              0          4596
Now I am confused , at result of first free command according to the top Quote the free memory for applications is 1504 MB , it's acceptable , but after I start the database it use 2G ram the second free command shows free memory is 1453 MB
while Swap is the same, It's not acceptable for me
And if you attention to the size of buffer and cached they have been increased but why ?
If the kernel release buffers and cached for applications when it is need so why in the second free command they have been increased ?

thank you