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can I set PAE and 3GB/Switch at the same BOOT.ini file?

Posted on 2010-04-05
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Last Modified: 2012-05-09
expert,

I had add PAE in Boot.ini file of windows 2003 EE.  Can I also set up 3GB/swith in Boot.ini file? how?
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows Server 2003, Enterprise" /noexecute=optout /fastdetect/PAE
--- 3GB/switch?
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows Server 2003, Enterprise" /noexecute=optout /fastdetect/3GB/Userva=3030

It look like the same file. I am not sure how to set up both of PAE and 3GB/swithch in one
windows 2003 EE server ? or only can set up each at time.
Can you help?
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Question by:yrcdba7
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12 Comments
 
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Expert Comment

by:Raja Jegan R
ID: 29839920
You can and need to enable both /3GB and /PAE switches at the end of boot.ini for your 32 bit machine to access more than or equal to 4 GB of memory in your machine..
And hope this helps in setting it out:

http://support.microsoft.com/kb/291988
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Assisted Solution

by:LMiller7
LMiller7 earned 1600 total points
ID: 29851579
You can set both PAE and /3GB in boot.ini. But you must understand that they serve entirely different purposes. PAE is used to allow access to physical memory above 4GB. The /3GB switch changes the virtual address split from 2GB-2GGB to 1GB-3GB. This is completely independent of how much RAM you have. It can be used and be useful with less than 4GB RAM and with much more. This setting has some serious implications and should only be used when appropriate.

Neither of these settings is needed or supported on a 64 bit OS.

Read this series of articles to learn more about the /3GB switch. There is a great deal of confusion surrounding this.

http://blogs.msdn.com/oldnewthing/archive/2004/08/22/218527.aspx
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Expert Comment

by:blandyuk
ID: 29901783
Read this article below:

http://www.sql-server-performance.com/articles/per/awe_memory_sql2000_p1.aspx

When using /PAE, you also need to set AWE in SQL Server to use the additional memory. All depends on how much RAM you have.
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Author Comment

by:yrcdba7
ID: 29917006

Expert,

Our server physical memory is 24 GB, if we want to set up 3GB/switch,  the physical memory RAM should be less than 16 GB from below link, is that correct?  should we have to take 8GB out or just leave 24GB in the server, then set up 3GB/switch? can you make clear?

From this link  http://support.microsoft.com/kb/283037/en-us

The preceding information is valid for programs that run when the /3GB switch is used. A
program that requests 3 GB of memory is more likely to be able to have more of its memory remain in physical memory rather than be paged out. This increases the performance of programs that are capable of using the /3GB switch. The exception is when the /3GB switch is used in conjunction with the /PAE switch. In this case, the operating system does not use any memory in excess of 16 GB. This behavior is caused by kernel virtual memory space considerations. Thus, if the system restarts with the /3GB entry in the Boot.ini file, and the system has more than 16 GB of physical memory, the additional physical random access memory (RAM) is not used by the operating system. Restarting the computer without the /3GB switch enables the use of all the physical memory.

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Expert Comment

by:blandyuk
ID: 29921871
If you have 24GB, set the /PAE switch and enable AWE in SQL Server. To enable AWE:

Right-click on server, "Properties", select "Memory" and check "Use AWE to allocate memory". When viewing SQL Server in task-manager, you'll notice the sqlserver.exe process will not be using much RAM but the overall physical system RAM will go up. This is because of how AWE works with system RAM.
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Accepted Solution

by:
LMiller7 earned 1600 total points
ID: 29922799
The maximum RAM size when using the /3GB switch is 16GB. And remember that that is a maximum, in many cases it will be difficult to obtain reliable operation with 16GB RAM. The switch constrains the system virtual address space to only 1GB (independent of RAM size). There isn't room in this space to store the larger translation tables necessary for more RAM.

Be certain that you really need the /3GB switch. As I said before, this has little to do with how physical memory is used. It can certainly be useful with SQL but it does have some serious implications. I am not an SQL expert so I will leave that part to others.

The best option if this is practical would be to use a 64 bit OS and suitable version of SQL. In that case all of these issues will not apply.
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Author Comment

by:yrcdba7
ID: 29924406
blandyuk,

Your opinion is just 24GB to add PAE and enable AWE, do not use 3GB/switch?
Is that correct?  Thank you.
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LVL 9

Expert Comment

by:blandyuk
ID: 29925020
AWE memory technology is used only for the RAM that exceeds the base 4GB of RAM, that's why the /3GB switch is needed to use as much of the RAM in your server as possible. If your server has 16GB or less of RAM, then using the /3GB switch is important. But if your server has more than 16GB of RAM, then you must not use the /3GB switch. The reason for this is because the 1GB of additional RAM provided by adding the /3GB switch is needed by the operating system in order to take advantage of all of the extra AWE memory. In other words, the operating system needs 2GB of RAM itself to mange the AWE memory if your server has more than 16GB of RAM. If 16GB or less of RAM is in a server, then the operating system only needs 1GB of RAM, allowing the other 1GB of RAM for use by SQL Server.
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Author Comment

by:yrcdba7
ID: 29927013

So if Windows 2003 R2 64bits, it is compitable with SQL server 2000 EE 32bit?
why? why not?
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Author Comment

by:yrcdba7
ID: 29927698

So if 24GB ram for AWE, it will take more than 1GB memory from OS memory. So I just use AWE only without 3GB/swith.  I thought 3GB can increase application memory from 2GB to 3GB. That will be good for SP and queries for performance.

I also wonder if my physical memory is 24GB, how much memory I should map to AWE for data cache memory?  ( 8GB, 16GB or 12GB or 20GB)
 
Thanks
0
 

Author Comment

by:yrcdba7
ID: 29949104
blandyuk,

you said: 'If you have 24GB, set the /PAE switch and enable AWE in SQL Server. To enable AWE:

Right-click on server, "Properties", select "Memory" and check "Use AWE to allocate memory". When viewing SQL Server in task-manager, you'll notice the sqlserver.exe process will not be using much RAM but the overall physical system RAM will go up. This is because of how AWE works with system RAM.Accept Multiple Solutions Accept as Solution '
---
you mean it is SQL server or windows server. I opened SQL server property but there is no AWE can check. My SQL SERVER IS 2k EE 32bit in windows 2k3 EE 32bit.
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Assisted Solution

by:blandyuk
blandyuk earned 400 total points
ID: 29949779
Ah, SQL 2000 :) ok, read this article:

http://msdn.microsoft.com/en-us/library/aa196705%28SQL.80%29.aspx

sp_configure 'show advanced options', 1
RECONFIGURE
GO
sp_configure 'awe enabled', 1
RECONFIGURE
GO
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