Re: Using AMM with Linux RAC
- From: Christo Kutrovsky <kutrovsky.oracle@xxxxxxxxx>
- To: troach@xxxxxxxxx
- Date: Tue, 9 Mar 2010 14:43:27 -0500
I don't think this is possible in current architecture.
I think easiest for this is to dynamic part of PGA in SGA :)
On Thu, Feb 18, 2010 at 12:00 PM, Thomas Roach <troach@xxxxxxxxx> wrote:
> Tanel,
>
> Is it possible for Oracle to eventually have AMM and hugepages support?
>
> I think I recall some blog posts by Kevin Closson on this topic and I don't
> recall if it was a limitation with the memory being able to dynamically
> resize and hugepages not supporting that?
>
> Thanks,
>
> Tom
>
>
> On Thu, Feb 18, 2010 at 11:02 AM, Tanel Poder <tanel@xxxxxxxxxx> wrote:
>
>> 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
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> 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.
>>>
>>>
>>>
>>
>
>
> --
> Thomas Roach
> 813-404-6066
> troach@xxxxxxxxx
>
--
Christo Kutrovsky
Senior Consultant
Pythian.com
I blog at http://www.pythian.com/blogs/
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