RE: SWAP Space Confusion Note 1354525.1

From: <Christopher.Taylor2_at_parallon.net>
Date: Tue, 22 Jan 2013 10:50:46 -0600
Message-ID: <F05D8DF1FB25F44085DB74CB916678E8856C07AABF_at_NADCWPMSGCMS10.hca.corpad.net>

Ah you have a good memory! I was on Windows in my previous incarnation ;) Mostly RedHat now with some AIX thrown in for good measure. We have a habit of over-allocating swap [in my opinion] in this shop - though I wanted to verify with the list what people thought about the note and limiting swap to 16GB. For example, most of your 64GB ram servers have 64GB of swap space.

Regards,

Chris

From: Niall Litchfield [mailto:niall.litchfield_at_gmail.com] Sent: Tuesday, January 22, 2013 10:29 AM To: Taylor Christopher - Nashville
Cc: ORACLE-L
Subject: Re: SWAP Space Confusion Note 1354525.1

Chris,

The 11g values at least have the benefit of being (mostly) consistent. If you follow the 10g guide on a system with 8gb of RAM you'd want 8gb of swap, a requirement that reduces to 7.5gb of SWAP for a system with 10gb of RAM. The same issue arises around the 2gb ram line as well of course. My take if you can afford it, set 16gb and monitor for swapping at the O/S level for a while assuming you don't see any ignore from then on in.

IIRC you might be running Windows in which case http://members.shaw.ca/bsanders/WindowsGeneralWeb/RAMVirtualMemoryPageFileEtc.htm is as good a guide as I am aware of, though it was largely written in 32bit days. if you are running 32bit windows then swapping isn't your highest priority improvement :)

On Tue, Jan 22, 2013 at 4:07 PM, <Christopher.Taylor2_at_parallon.net<mailto:Christopher.Taylor2_at_parallon.net>> wrote: If I'm reading this right, for systems with a lot of RAM, the recommended value for 10.2 and above is 16GB for swap when memory is 16GB or higher, *OR* am I reading this entirely incorrectly? It's not exactly clear.

Ref: 10gR2 SWAP Space Requirement For Systems Having Huge RAM [ID 1354525.1]

Per the above doc, the "GOAL" section says: "For Systems having Huge Memory (RAM) is it really required to have SWAP Space as 0.75 X RAM"

Per the Solution it says:
Solution
As per the Documentation below is the swap space requirement for 10gR2:

RAM                           Swap Space
===                           =========Up to 512 MB                  2 times the size of RAM

Between 1024 MB and 2048 MB 1.5 times the size of RAM Between 2049 MB and 8192 MB Equal to the size of RAM More than 8192 MB 0.75 times the size of RAM

As part of Unpublished Documentation Bug below are the new values for SWAP Space requirements approved by Oracle Development Team and also updated in 11.1 and 11.2 Install guides as below:

RAM                       Swap Space
===                       =========Between 1 GB and 2 GB     1.5 times the size of RAM
Between 2 GB and 16 GB    Equal to the size of RAM
More than 16 GB           16 GB

All the other pre-requisites mentioned for Oracle Database Software in the installation guide published by Oracle Development Team need to be completed as appropriate.

You may proceed with the swap space requirements as mentioned in the updated guides and ignore any swap related warnings during the installation of 10gR2.

Chris Taylor
Oracle DBA
Parallon IT&S

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

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Niall Litchfield
Oracle DBA
http://www.orawin.info

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http://www.freelists.org/webpage/oracle-l Received on Tue Jan 22 2013 - 17:50:46 CET