AWE Memory?

Hi all?
I've tried reading about how AWE memory works but I really can't figure it
out...
I have a dedicated SQL Server 2000 SP4, Ent Edition that runs on a Windows
2003 Advanced server. The box has 4 Gbytes RAM and I want to be able to use
as much as possible of the RAM for SQL Server.
I have entered the Boot.ini with the /3GB parameter to allow SQL Server to
use 3 Gbytes of RAM instead of the default of 2 Gbyte. But there is still 1
Gbyte "left" in the box to be used by OS. At least 512Mbytes of that free
space is in my interest to use for SQL Server.
If I enable AWE memory and set the max server memory to 3,5 Gbyte will I be
able to use that extra 512 Mbytes as well? Or is AWE only for boxes with more
than 4 Gbytes RAM?
regards
fredrik
> If I enable AWE memory and set the max server memory to 3,5 Gbyte will I
> be
> able to use that extra 512 Mbytes as well? Or is AWE only for boxes with
> more
> than 4 Gbytes RAM?
I don't think you need to enable AWE memory in that case
AWE memory is used only for the RAM that exceeds the base 4GB of RAM.
http://support.microsoft.com/kb/274750
http://www.sql-server-performance.com/awe_memory.asp
"Fredrik" <Fredrik@.discussions.microsoft.com> wrote in message
news:14470AFA-E4E7-4D2E-A605-B3651A618913@.microsoft.com...
> Hi all?
> I've tried reading about how AWE memory works but I really can't figure it
> out...
> I have a dedicated SQL Server 2000 SP4, Ent Edition that runs on a Windows
> 2003 Advanced server. The box has 4 Gbytes RAM and I want to be able to
> use
> as much as possible of the RAM for SQL Server.
> I have entered the Boot.ini with the /3GB parameter to allow SQL Server to
> use 3 Gbytes of RAM instead of the default of 2 Gbyte. But there is still
> 1
> Gbyte "left" in the box to be used by OS. At least 512Mbytes of that free
> space is in my interest to use for SQL Server.
> If I enable AWE memory and set the max server memory to 3,5 Gbyte will I
> be
> able to use that extra 512 Mbytes as well? Or is AWE only for boxes with
> more
> than 4 Gbytes RAM?
> regards
> fredrik
|||If we are talking about the memory usage as measured by the SQL counter Total
Server Memory, you need to enable AWE to use more than 3GB. It is not correct
that AWE is used only for RAM that exceeds 4GB.
Linchi
"Uri Dimant" wrote:

> I don't think you need to enable AWE memory in that case
> AWE memory is used only for the RAM that exceeds the base 4GB of RAM.
> http://support.microsoft.com/kb/274750
> http://www.sql-server-performance.com/awe_memory.asp
>
> "Fredrik" <Fredrik@.discussions.microsoft.com> wrote in message
> news:14470AFA-E4E7-4D2E-A605-B3651A618913@.microsoft.com...
>
>
|||Could you give us some support on that assertion? (It is not correct that AWE is used only for RAM that exceeds 4GB." If my information is incorrect, I would like to update it to reflect that which is indeed correct...
I've been going by the following:
"AWE is a set of memory management extensions to the Microsoft Win32? API that allows applications to address memory beyond 4 GB."
From: http://download.microsoft.com/downlo...dv64BitEnv.doc
Arnie Rowland, Ph.D.
Westwood Consulting, Inc
Most good judgment comes from experience.
Most experience comes from bad judgment.
- Anonymous
"Linchi Shea" <LinchiShea@.discussions.microsoft.com> wrote in message news:1C1B6C5F-B795-4209-B6C9-06495AE71796@.microsoft.com...[vbcol=seagreen]
> If we are talking about the memory usage as measured by the SQL counter Total
> Server Memory, you need to enable AWE to use more than 3GB. It is not correct
> that AWE is used only for RAM that exceeds 4GB.
> Linchi
> "Uri Dimant" wrote:
|||Could you give us some support on that assertion? (It is not correct that AWE is used only for RAM that exceeds 4GB." If my information is incorrect, I would like to update it to reflect that which is indeed correct...
I've been going by the following:
"AWE is a set of memory management extensions to the Microsoft Win32? API that allows applications to address memory beyond 4 GB."
From: http://download.microsoft.com/downlo...dv64BitEnv.doc
Arnie Rowland, Ph.D.
Westwood Consulting, Inc
Most good judgment comes from experience.
Most experience comes from bad judgment.
- Anonymous
"Linchi Shea" <LinchiShea@.discussions.microsoft.com> wrote in message news:1C1B6C5F-B795-4209-B6C9-06495AE71796@.microsoft.com...[vbcol=seagreen]
> If we are talking about the memory usage as measured by the SQL counter Total
> Server Memory, you need to enable AWE to use more than 3GB. It is not correct
> that AWE is used only for RAM that exceeds 4GB.
> Linchi
> "Uri Dimant" wrote:
|||What you need instead of all these buggy flags is to move to x64 where the
memory issue doesn't exist at all. Of course you also need to make sure you
run SQL Server 64 bit as well, not the 32 bit version on a 64 bit system.
Unfortunately very few dedicated hosts offer Windows 2003 x64.
KL
"Fredrik" <Fredrik@.discussions.microsoft.com> skrev i meddelandet
news:14470AFA-E4E7-4D2E-A605-B3651A618913@.microsoft.com...
> Hi all?
> I've tried reading about how AWE memory works but I really can't figure it
> out...
> I have a dedicated SQL Server 2000 SP4, Ent Edition that runs on a Windows
> 2003 Advanced server. The box has 4 Gbytes RAM and I want to be able to
> use
> as much as possible of the RAM for SQL Server.
> I have entered the Boot.ini with the /3GB parameter to allow SQL Server to
> use 3 Gbytes of RAM instead of the default of 2 Gbyte. But there is still
> 1
> Gbyte "left" in the box to be used by OS. At least 512Mbytes of that free
> space is in my interest to use for SQL Server.
> If I enable AWE memory and set the max server memory to 3,5 Gbyte will I
> be
> able to use that extra 512 Mbytes as well? Or is AWE only for boxes with
> more
> than 4 Gbytes RAM?
> regards
> fredrik
|||Here's some empirical evidence from the test scenarios in which severe memory
pressure was put on the instance with 4GB of RAM. If the following comes out
unreadable format-wise, drop me an email and I send you the charts.
Linchi
linchi_shea@.take-this-out-FIRSTml.com
Observed Target Sqlservr.exe
Max server AWE 3GB /Total server memory observed
memory (MB) enabled enabled memory (MB) on TaskMan (MB)
500 N N 500 560
1000 N N 1000 1060
1500 N N 1206 1266
2000 N N 1206 1266
2500 N N 1206 1266
3000 N N 1206 1266
3500 N N 1206 1266
Observed Target Sqlservr.exe
Max server AWE 3GB /Total server memory observed
memory (MB) enabled enabled memory (MB) on TaskMan (MB)
500 Y N 500 61
1000 Y N 1000 67
1500 Y N 1500 71
2000 Y N 2000 76
2500 Y N 2500 81
3000 Y N 3000 86
3500 Y N 3500 90
Observed Target Sqlservr.exe
Max server AWE 3GB /Total server memory observed
memory (MB) enabled enabled memory (MB) on TaskMan (MB)
500 Y Y 500 65
1000 Y Y 1000 70
1500 Y Y 1500 75
2000 Y Y 2000 80
2500 Y Y 2500 84
3000 Y Y 3000 89
3500 Y Y 3500 94
Observed Target Sqlservr.exe
Max server AWE 3GB /Total server memory observed
memory (MB) enabled enabled memory (MB) on TaskMan (MB)
500 N Y 500 550
1000 N Y 1000 1055
1500 N Y 1500 1561
2000 N Y 2000 2067
2500 N Y 2219 2290
3000 N Y 2219 2290
3500 N Y 2219 2290
"Arnie Rowland" wrote:
[vbcol=seagreen]
> Could you give us some support on that assertion? (It is not correct that AWE is used only for RAM that exceeds 4GB." If my information is incorrect, I would like to update it to reflect that which is indeed correct...
> I've been going by the following:
> "AWE is a set of memory management extensions to the Microsoft Win32? API that allows applications to address memory beyond 4 GB."
> From: http://download.microsoft.com/downlo...dv64BitEnv.doc
> --
> Arnie Rowland, Ph.D.
> Westwood Consulting, Inc
> Most good judgment comes from experience.
> Most experience comes from bad judgment.
> - Anonymous
>
> "Linchi Shea" <LinchiShea@.discussions.microsoft.com> wrote in message news:1C1B6C5F-B795-4209-B6C9-06495AE71796@.microsoft.com...
|||Hi Fredrick,
If your server is running 4 GB of memory, then you don't want to have
SQL Server running more than 3 GB. Part of the reason for that is that
you have to leave sufficient space for the OS to operate and 1 GB of
RAN for the OS is a good amount (yeah, I know it'll run on less). The
other reason is that AWE requires 1 GB of RAM just to manage the
memory swaps that are going on. So running AWE on a 4 GB server is
likely to make things worse, not better.
So if you really think you need to be running AWE:
(1) Have at least 6 GB of memory on the server and that this is the
only instance of SQL Server running on the server.
(2) After enabling AWE and setting the /3GB and /PAE switches in the
boot.ini file, configure your max memory setting to equal your total
memory minus 1 GB (for the OS). If you don't configure the max memory
setting you leave open the possibility that SQL Server will grab all
but 128 MB of RAM to operate, leaving you a memory-starved OS that
will perform poorly (if at all) due to heavy paging of the OS to the
swap file.
Before enabling AWE you need to do your homework on whether the extra
memory will actually do you any good. Our team manages 500+ instances
of SQL 2000 & 2005 and in all the 15+ years I've worked as a SQL DBA
the vast majority of performance issues I've seen are due to
application and/or database design. You'll be amazed at how well SQL
will run on 3 GB of RAM, especially with a well-designed system. Good
luck to you!
On Fri, 13 Oct 2006 00:03:01 -0700, Fredrik
<Fredrik@.discussions.microsoft.com> wrote:

>Hi all?
>I've tried reading about how AWE memory works but I really can't figure it
>out...
>I have a dedicated SQL Server 2000 SP4, Ent Edition that runs on a Windows
>2003 Advanced server. The box has 4 Gbytes RAM and I want to be able to use
>as much as possible of the RAM for SQL Server.
>I have entered the Boot.ini with the /3GB parameter to allow SQL Server to
>use 3 Gbytes of RAM instead of the default of 2 Gbyte. But there is still 1
>Gbyte "left" in the box to be used by OS. At least 512Mbytes of that free
>space is in my interest to use for SQL Server.
>If I enable AWE memory and set the max server memory to 3,5 Gbyte will I be
>able to use that extra 512 Mbytes as well? Or is AWE only for boxes with more
>than 4 Gbytes RAM?
>regards
>fredrik