Re: Using AMM with Linux RAC
Date: Thu, 18 Feb 2010 14:01:33 +0000
Message-ID: <5e317f311002180601r19032f1csb9632ccfc56671a9_at_mail.gmail.com>
Hi,
If the database instance has not done much work yet, the SGA probably has not had the need to allocate more memory for itself.
Yes, if /dev/shm is sized to 16GB then the memory_target cannot exceed this, because Oracle will not let the database startup if there is not at least memory_target amount of free space in /dev/shm. As you probably guessed, the OS sized /dev/shm at 50% of RAM, but it can be resized. I cannot provide the instructions for them, but they are out there.
Regards
Pete
On Thu, Feb 18, 2010 at 1:51 PM, Sherrie Kubis < Sherrie.Kubis_at_swfwmd.state.fl.us> 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
>
>
>
>
>
>
>
> IMPORTANT NOTICE: All E-mail sent to or from this address are public record and archived. The Southwest Florida Water Management District does not allow use of District equipment and E-mail facilities for non-District business purposes.
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>
-- Regards Pete -- http://www.freelists.org/webpage/oracle-lReceived on Thu Feb 18 2010 - 08:01:33 CST