"Allocating" and "using" are 2 rather different word in a linux-box.
When Oracle starts and allocated 4G of SGA, you will most likely not see
must usage on the memory as the memory-pages are just reserved for the
purpose.
You will see memory usage grow when the database starts working and the
buffer cache gets filled as it is the writing to the memory which brings it
into use - and thus visibly allocated.
My own little Oracle 9.2.0.6, configured with 400MB uses ~58MB on startup -
including binary core image, which is 51MB. However - starting of a real
database burner makes it utilize a total of ~500MB for all server procs and
SGA. This happens quite fast.
My 10g uses ~70MB in startup regardless of SGA size. But when used......
wooo-haa....
/Stig
----Original Message Follows---- From: Charlotte Hammond <charlottejanehammond@xxxxxxxxx> Reply-To: charlottejanehammond@xxxxxxxxx To: oracle-l@xxxxxxxxxxxxx Subject: Dude, Where's My Database? Date: Tue, 18 Jul 2006 07:15:22 -0700 (PDT)
Hi All,
My database is configured to use approx. 4Gb of memory:
Connected to: Oracle9i Release 9.2.0.6.0 - 64bit Production JServer Release 9.2.0.6.0 - Production
SQL> select * 2 from v$sga 3 /
NAME VALUE -------------------- ---------- Fixed Size 748656 Variable Size 805306368 Database Buffers 3355443200 Redo Buffers 1323008
Yet, Linux is saying there's < 1Gb physical memory in use and no swap. Where is my database?
(Apologies for the formating)
top - 16:08:21 up 2:17, 4 users, load average: 0.12, 0.11, 0.04 Tasks: 102 total, 1 running, 101 sleeping, 0 stopped, 0 zombie Cpu(s): 0.4% us, 0.1% sy, 0.0% ni, 99.3% id, 0.2% wa, 0.0% hi, 0.0% si Mem: 8169180k total, 906124k used, 7263056k free, 39152k buffers Swap: 2031608k total, 0k used, 2031608k free, 742984k cached
The database has been up for 2 hours but is very lightly loaded. Linux version is:
Linux 2.6.9-34.0.1.ELsmp #1 SMP Wed May 17 16:59:36 EDT 2006 x86_64 x86_64 x86_64 GNU/Linux
Doesn't Oracle allocate the entire SGA at start-up (or is on a demand basis?) I'd always understood it to be the former, in which case why can't I see it in memory using top?
Thanks for any info
Charlotte
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