AWE

Hi,
Imagine that my server has 4GB physical memory. I have added /3GB switch to boot.ini.
Should I enable AWE configuration for my SQL Server to use 3 GB address space? Or AWE must only be used when I have more than 4GB memory?
Thanks in advance
Hello,
AWE can be used only if you have more than 4 GB physical memory. But The
/3GB switch is used to tell SQL Server to take advantage of 3GB out of the
base 4GB
of RAM that Windows OS supports natively. If you don't specify this option,
then SQL Server will only take advantage of 2GB of the first 4GB of RAM in
the
server, essentially wasting 1GB of RAM
Please post the OS and SQL Server edition. This is because For SQL Server
2005 - 64 bit running in Windows 2003 you donot want any changes in BOOT.INI
to use the additional RAM.
Thanks
Hari
"Leila" <Leilas@.hotpop.com> wrote in message
news:OEze$NnfHHA.2432@.TK2MSFTNGP03.phx.gbl...
> Hi,
> Imagine that my server has 4GB physical memory. I have added /3GB switch
> to boot.ini.
> Should I enable AWE configuration for my SQL Server to use 3 GB address
> space? Or AWE must only be used when I have more than 4GB memory?
> Thanks in advance,
> Leila
>
|||> AWE can be used only if you have more than 4 GB physical memory.
That's not correct. Take a look at some empirical data at
http://sqlblog.com/blogs/linchi_shea/default.aspx?p=2
Linchi
"Hari Prasad" wrote:

> Hello,
> AWE can be used only if you have more than 4 GB physical memory. But The
> /3GB switch is used to tell SQL Server to take advantage of 3GB out of the
> base 4GB
> of RAM that Windows OS supports natively. If you don't specify this option,
> then SQL Server will only take advantage of 2GB of the first 4GB of RAM in
> the
> server, essentially wasting 1GB of RAM
> Please post the OS and SQL Server edition. This is because For SQL Server
> 2005 - 64 bit running in Windows 2003 you donot want any changes in BOOT.INI
> to use the additional RAM.
> Thanks
> Hari
>
> "Leila" <Leilas@.hotpop.com> wrote in message
> news:OEze$NnfHHA.2432@.TK2MSFTNGP03.phx.gbl...
>
>
|||Hello Linchi,
If I remember correct for a server with 4 GB RAM running in SQL Server 2005
32 bit and Windows 2003 Advanced, all I did is just /3GB switch in Boot.ini
to
use 3 GB RAM. I will take a look into the server on Moday and keep you
posted
Thanks
Hari
"Linchi Shea" <LinchiShea@.discussions.microsoft.com> wrote in message
news:45A920F2-86E6-4A86-A1B1-8306C3077E8B@.microsoft.com...[vbcol=seagreen]
> That's not correct. Take a look at some empirical data at
> http://sqlblog.com/blogs/linchi_shea/default.aspx?p=2
> Linchi
> "Hari Prasad" wrote:
|||Hari;
My comment had nothing to do with whether /3GB is used, how it should be
used, or what impact it may have. I was commenting on the statement that AWE
can be used only if you have more than 4GB physical memory. As the data at
the link indicate that setting AWE has an impact on SQL Server memory
consumption even with 4GB physical memory. And if you want your bpool to
consume a certain amount of memory under 4GB, you may need to use AWE to
accomplish that.
Now, whether or not you should use AWE with less than 4GB of physical memory
or whether there is any compelling rason for doing so are entirely different
issue.
Linchi
"Hari Prasad" wrote:

> Hello Linchi,
> If I remember correct for a server with 4 GB RAM running in SQL Server 2005
> 32 bit and Windows 2003 Advanced, all I did is just /3GB switch in Boot.ini
> to
> use 3 GB RAM. I will take a look into the server on Moday and keep you
> posted
> Thanks
> Hari
>
>
> "Linchi Shea" <LinchiShea@.discussions.microsoft.com> wrote in message
> news:45A920F2-86E6-4A86-A1B1-8306C3077E8B@.microsoft.com...
>
>
|||Thanks Hari and Linchi!
Based on documents that I have read, /3GB causes that kernel mode use only
1GB and Virtual Address Space for applications therefore can reserve up to
3GB. Whereas 32-bit based Windows can address up to 4GB of memory, therefore
I think by using /3GB switch we don't need to enable AWE for SQL Server to
use 3GB. Because we are not beyond the 4GB limit of addressing in this
situation.
"Linchi Shea" <LinchiShea@.discussions.microsoft.com> wrote in message
news:F6FB03D7-3B0F-4CD1-B2A2-BBFD660502EE@.microsoft.com...[vbcol=seagreen]
> Hari;
> My comment had nothing to do with whether /3GB is used, how it should be
> used, or what impact it may have. I was commenting on the statement that
> AWE
> can be used only if you have more than 4GB physical memory. As the data at
> the link indicate that setting AWE has an impact on SQL Server memory
> consumption even with 4GB physical memory. And if you want your bpool to
> consume a certain amount of memory under 4GB, you may need to use AWE to
> accomplish that.
> Now, whether or not you should use AWE with less than 4GB of physical
> memory
> or whether there is any compelling rason for doing so are entirely
> different
> issue.
> Linchi
> "Hari Prasad" wrote:
|||That is correct and the most recommended approach with 4GB.
Andrew J. Kelly SQL MVP
"Leila" <Leilas@.hotpop.com> wrote in message
news:ucNNgjyfHHA.2640@.TK2MSFTNGP06.phx.gbl...
> Thanks Hari and Linchi!
> Based on documents that I have read, /3GB causes that kernel mode use only
> 1GB and Virtual Address Space for applications therefore can reserve up to
> 3GB. Whereas 32-bit based Windows can address up to 4GB of memory,
> therefore I think by using /3GB switch we don't need to enable AWE for SQL
> Server to use 3GB. Because we are not beyond the 4GB limit of addressing
> in this situation.
>
> "Linchi Shea" <LinchiShea@.discussions.microsoft.com> wrote in message
> news:F6FB03D7-3B0F-4CD1-B2A2-BBFD660502EE@.microsoft.com...
>
|||Thanks indeed Andrew :-)
Now these two conditions:
1) 5GB RAM + /PAE switch + /3GB switch
2) 6GB RAM + /PAE switch
Can I say that neither of these situations need AWE for SQL Server?
"Andrew J. Kelly" <sqlmvpnooospam@.shadhawk.com> wrote in message
news:uW%23DbP3fHHA.4936@.TK2MSFTNGP04.phx.gbl...
> That is correct and the most recommended approach with 4GB.
> --
> Andrew J. Kelly SQL MVP
> "Leila" <Leilas@.hotpop.com> wrote in message
> news:ucNNgjyfHHA.2640@.TK2MSFTNGP06.phx.gbl...
>
|||Depends on how much you want for SQL Server. If you want more than 3GB you
must use AWE (in addition to PAE) on 32 bit systems. In either case you
should always leave at least a GB for the OS when using AWE since it is not
dynamic. 2GB if going over 12GB total. The /3GB is optional depending on
how much you need for non-buffer pool memory such as procedure cache,
connections etc.
Andrew J. Kelly SQL MVP
"Leila" <Leilas@.hotpop.com> wrote in message
news:%2399LSA4fHHA.2396@.TK2MSFTNGP04.phx.gbl...
> Thanks indeed Andrew :-)
> Now these two conditions:
> 1) 5GB RAM + /PAE switch + /3GB switch
> 2) 6GB RAM + /PAE switch
> Can I say that neither of these situations need AWE for SQL Server?
>
> "Andrew J. Kelly" <sqlmvpnooospam@.shadhawk.com> wrote in message
> news:uW%23DbP3fHHA.4936@.TK2MSFTNGP04.phx.gbl...
>
|||If I have 5GB memory and I use both /PAE and /3GB, then SQL Server can use
up to 4GB memory and this is not beyond 32-bit addressing. Why should I
enable AWE for SQL Server?
"Andrew J. Kelly" <sqlmvpnooospam@.shadhawk.com> wrote in message
news:utisfW8fHHA.668@.TK2MSFTNGP05.phx.gbl...
> Depends on how much you want for SQL Server. If you want more than 3GB you
> must use AWE (in addition to PAE) on 32 bit systems. In either case you
> should always leave at least a GB for the OS when using AWE since it is
> not dynamic. 2GB if going over 12GB total. The /3GB is optional depending
> on how much you need for non-buffer pool memory such as procedure cache,
> connections etc.
> --
> Andrew J. Kelly SQL MVP
> "Leila" <Leilas@.hotpop.com> wrote in message
> news:%2399LSA4fHHA.2396@.TK2MSFTNGP04.phx.gbl...
>