AW: Re: amm vs. asmm

From: <ahmed.fikri_at_t-online.de>
Date: Thu, 23 Jan 2020 19:27:45 +0100 (CET)
Message-ID: <1579804065863.8727675.9cf8d075aee825c38cad637f35a9674976f5b31b_at_spica.telekom.de>

it is Aix Os.

Regards
Ahmed

---

Gesendet mit der Telekom Mail App
<https://kommunikationsdienste.t-online.de/redirects/email_app_android_sendmail_footer>

• Original-Nachricht --- Von: Tim Hall Betreff: Re: amm vs. asmm Datum: 23.01.2020, 19:11 Uhr An: ahmed.fikri_at_t-online.de Cc: oracle-l_at_freelists.org

Hi.

Automatic Memory Management (AMM) doesn't support HugePages. As a result, you have potential for wasting lots of memory on page tables.

https://oracle-base.com/articles/linux/configuring-huge-pages-for-oracle-on-linux-64
<https://oracle-base.com/articles/linux/configuring-huge-pages-for-oracle-on-linux-64>
 

In contrast, Automatic Shared Memory Management (ASMM) does support HugePages.

The DBCA has some guidance for this decision process. From the 12.2 documentation:

https://docs.oracle.com/en/database/oracle/oracle-database/12.2/admin/managing-memory.html#GUID-04EFED7D-D1F1-43C3-B78F-0FF9AFAC02B0
<https://docs.oracle.com/en/database/oracle/oracle-database/12.2/admin/managing-memory.html#GUID-04EFED7D-D1F1-43C3-B78F-0FF9AFAC02B0>
   

" Oracle recommends automatic memory management for databases where the total size of the SGA and PGA memory is less than or equal to four gigabytes."

" If you create your database with Database Configuration Assistant (DBCA) and choose the basic installation option, automatic memory management is enabled when system memory is less than or equal to 4 gigabytes. When system memory is greater than 4 gigabytes, automatic memory management is disabled, and automatic shared memory management is enabled. If you choose advanced installation, then DBCA enables you to select automatic memory management or automatic shared memory management."

Rules of thumb are always lies, but I never use AMM. ;)

Note. I guess there may be differences of opinions on some operating systems, but if it's not Linux, I'm not interested. :)

Cheers

Tim...

On Thu, Jan 23, 2020 at 5:39 PM ahmed.fikri_at_t-online.de
<mailto:ahmed.fikri_at_t-online.de> < ahmed.fikri_at_t-online.de
<mailto:ahmed.fikri_at_t-online.de> > wrote:
  Hi,

  Coincidentally, I have seen in a productive DB that it is used AMM   instead of Asmm. I'm a developer with a bit of a dba knowledge. Our   software uses a huge db and does complex calculations.   In my experience, using amm we had only problems with other customers on   11g and 12c

  In addition, I have read many articles, that recommend to use asmm   instead of amm.
  The DBA is ready to use Asmm, but only if I convince him.

  The question: It is true that amm is not good (huge db, lot of sessions,   parallels work)
  If I'm right how can I connvince the dba?

  Thanks
  Ahmed

  Gesendet mit der Telekom Mail App

--
http://www.freelists.org/webpage/oracle-l

Received on Thu Jan 23 2020 - 19:27:45 CET