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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Oracle taking too much physical memory
I try to keep the total SGAs of all instances below 50% of RAM for Windowz machines, but maybe that's another urban legend. WinNT tried to keep 95% of its RAM empty. It thinks that it's a heavy lifting operating system with thousands of users clamoring for its attention (sort of like most IT pros) so on the first free machine cycle it will write the RAM's contents to disk and free up the RAM. Simplistic explanation -- but good enough for Windows. Unless Bill Gates and Larry Ellison have kissed and made up, I would expect W2K to show the same behavior.
"MacGregor,
Ian A." <ian To: Multiple recipients of list ORACLE-L
@SLAC.Stanfor <ORACLE-L_at_fatcity.com>
d.EDU> cc:
Sent by: root Subject: RE: Oracle taking too much physical
memory
03/13/2002
03:59 PM
Please
respond to
ORACLE-L
I don't know about W2K. All our databases are on Solaris. I try to keep my SGA's at about 25% of physical memory.
Ian MacGregor
Stanford Linear Acclerator Center
ian_at_slac.stanford.edu
-----Original Message-----
Sent: Wednesday, March 13, 2002 10:04 AM
To: Multiple recipients of list ORACLE-L
My bad. I didn't notice that he was doing a select * from v$sga and thought that it was the init.ora parameters.
My comments on the SGA size were based on WinNT 4.0. I assume, from your comments, that W2K is better about not swapping the RAM out to disk.
"MacGregor,
Ian A." <ian To: Multiple recipients of
list ORACLE-L
@SLAC.Stanfor <ORACLE-L_at_fatcity.com>
d.EDU> cc:
Sent by: root Subject: RE: Oracle taking too
much physical
memory
03/13/2002
11:53 AM
Please
respond to
ORACLE-L
You have one gigabyte of memory on your machine and your SGA is over 700 MB. That seems excessive I doubt you need 640 megabytes' worth of block buffers. There is nothing wrong by the way with nearly exhausting physical memory. However improperly assigning it is a problem, as is excessive paging.
Ian MacGregor
Stanford Linear Accelerator Center
ian_at_SLAC.Stanford.edu
-----Original Message-----
Sent: Wednesday, March 13, 2002 7:29 AM
To: Multiple recipients of list ORACLE-L
Hi gurus,
My Production Box has 1Gb Ram with single 933Mhz PIII processor , though the db is not that big (4 GB), the oracle process is taking too much of memory, causing server to slow down on peak times of the day, and even after words, tonight, I looked up the memory which ORACLE.EXE has taken, its almost 900 MB, why is that so ???
The last restart was a month ago as far as I remember, is this an OPERATING SYSTEM tuning problem or database tuning is required?
MY pagefile size is almost 2 GB, but the STATISTICS show that only 4-5 MB of physical memory is free, means the most of the physical memory is used in ORACLE processes,
The sga size is following,
SQL> select * from v$sga
NAME VALUE
-------------------- ----------
Fixed Size 75804
Variable Size 90701824
Database Buffers 655360000
Redo Buffers 77824
If db tuning is needed, from what point I should start,
Also, I haven't analyzed the schemas from long, The occasion DEAD LOCK problems also show up,
Can anybody shed some light, where the choke point is ???
Help and suggestions welcomed,
Thanks in Advance,
Arslan Zaheer Dar
arslandar_at_skm.org.pk
Database Administrator
Shaukat Khanum Memorial Cancer Hospital & Research Centre
www.shaukatkhanum.org.pk
+ 92 (042) 5180725 - 34 Ext: 2323
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