analyzing SGA memory footprint

From: Ed Stevens <spamdump_at_nospam.noway.nohow>
Date: Thu, 11 Apr 2002 15:46:38 GMT
Message-ID: <3cb5ae60.252137194@ausnews.austin.ibm.com>

Platform: Oracle SE 8.0.5 and 8.1.7 on NT

I'm doing some capacity analysis on our DB servers, and looking at the total memory requirements. Most servers are running multiple DBs. Not sure exactly what numbers I should be looking at. Summing up all the values returned from v$sga and v$sgastat give different values:

SQL> select sum(value) from v$sga;

SUM(VALUE)

---

  29917184

SQL> select sum(bytes) from v$sgastat;

SUM(BYTES)

---

  29896356

My idea was to take one of these values from each sid running on a server, sum them all up, and compare it to the total physical memory as reported by NT. The rule I've seen frequently quoted is that the total of all the sids should not be more than 1/3 of the physical memory.

Am I way off base? Which, if any, of the numbers above should I be looking at, or what other numbers should I be using instead? Received on Thu Apr 11 2002 - 10:46:38 CDT