Re: Using AMM with Linux RAC
- From: Tanel Poder <tanel@xxxxxxxxxx>
- To: Sherrie.Kubis@xxxxxxxxxxxxxxxxxx
- Date: Fri, 19 Feb 2010 00:02:08 +0800
Hi Sherrie,
The memory which is reserved for PGA_AGGREGATE_TARGET will not show up in
/dev/shm as it's not shared (PGAs are still allocated using process-private
memory).
You can query V$MEMORY_DYNAMIC_COMPONENTS to see how Oracle is currently
using the memory:
SQL> select component, current_size from v$memory_dynamic_components where
component like '%Target%';
COMPONENT CURRENT_SIZE
------------------------------ ------------
SGA Target 545259520
PGA Target 293601280
Note that hugepages are not used with AMM on Linux so you may be not getting
all the performance out of your hardware...
--
Tanel Poder
http://tech.e2sn.com
http://blog.tanelpoder.com
On Thu, Feb 18, 2010 at 9:51 PM, Sherrie Kubis <
Sherrie.Kubis@xxxxxxxxxxxxxxxxxx> wrote:
> We have a 3-node (each 32 gb ram) Linux RAC cluster running Oracle
> 11.1.0.7, 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.
>
>
>
> *Sherrie Kubis *
>
> Southwest Florida Water Management District
>
>
>
>
>
>
>
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