Using AMM with Linux RAC
Date: Thu, 18 Feb 2010 08:51:14 -0500
We have a 3-node (each 32 gb ram) Linux RAC cluster running Oracle 188.8.131.52, housing 4 instances with a total memory_target of 8.75 gb. OEM shows 29% ram is used. We are using AMM.
The free -mt command shows:
total used free shared buffers cached
Mem: 32189 31519 669 0 1250 25168
-/+ buffers/cache: 5101 27088
Swap: 32767 39 32728
Total: 64957 31559 33397
It looks like tmpfs is 16gb:
df -k /dev/shm
Filesystem 1K-blocks Used Available Use% Mounted on
tmpfs 16481056 5604532 10876524 35% /dev/shm
We are seeing 5.6gb of memory used, so I'm confused about why the SGAs are defined to consume 8.75gb, but we only see 5.6gb used. I read that the SGA, by default, takes 60% of memory_target and pga gets the rest. Because there are not yet many connections, is this why we see a lower value?
Does the tmpfs at 16gb mean we can only use 16gb of ram for our databases?
Any insights would be appreciated. We are just starting out with Linux and Posix-Style shared memory management, quite different than shared semaphore memory segments that we were used to.
Southwest Florida Water Management District
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