PAE option in Win2k3

Hi,

Due to some requirement for SAP in Win2K3 with 32-bit systems we have to
enable the /3GB option as per Microsoft KB article 283037.
In the article, it is mentioned about PAE switch. I want to know, is there
any difference between /PAE and /3GB options ? If i enable just /PAE in
Windows is it ok or i have to enable /3GB option as required ?

Please guide. Thanks in advance.

abckid.

 

/PAE and /3GB are two different things.

/3GB - in the original 32-bit architecture, the total address space is 4GB.
This was originaly divided in half. 2GB for OS and 2GB for apps. The 3GB
says that app can address max 3GB, leaving only 1GB for the OS.

/PAE - When it became obvious that 4GB limit is going to be a problem, Intel
added 4 more address lines to it's processors, hence 2^4=16, 16*4GB=64GB
max. IOW PAE enables the use of 64GB max in a 32-bit architecture.

Conclusion.
Enable these switches as instructed and don't assume that one includes the
other.

"abckid" <abckid@discussions.microsoft.com> wrote in message
news:8B1DBE78-7D39-4313-BAB9-3A044D88BD25@microsoft.com...
> Hi,
>
> Due to some requirement for SAP in Win2K3 with 32-bit systems we have to
> enable the /3GB option as per Microsoft KB article 283037.
> In the article, it is mentioned about PAE switch. I want to know, is there
> any difference between /PAE and /3GB options ? If i enable just /PAE in
> Windows is it ok or i have to enable /3GB option as required ?
>
> Please guide. Thanks in advance.
>
> abckid.

 

Hi,

Thanks for receptive reply.

I have the note from SAP to first enable 3GB and then have mentioned in step
2 to Activate the 3 GB boot option according to Microsoft KB article 283037.
I will copy the steps as below,
######################
1. The Windows Server operating system family (as of Windows 2000
Advanced Server), a special boot option provides a 3 GB address space
for each process. Programs that are to use this 3 GB address space
must be prepared by a flag in program header. To do this, Windows must
be installed again, or an already existing Windows version must be set
up according to the Microsoft guidelines.

2. Activate the 3 GB boot option according to Microsoft KB article 283037.
#######################

They have just mentioned about 3GB, but also mentioned that we have to
install windows again !!! We have system with 24GB of physical RAM. So i
think /PAE should be used.

Please guide more on this. Thanks again

abckid.

"Dusko Savatovic" wrote:

> /PAE and /3GB are two different things.
>
> /3GB - in the original 32-bit architecture, the total address space is 4GB.
> This was originaly divided in half. 2GB for OS and 2GB for apps. The 3GB
> says that app can address max 3GB, leaving only 1GB for the OS.
>
> /PAE - When it became obvious that 4GB limit is going to be a problem, Intel
> added 4 more address lines to it's processors, hence 2^4=16, 16*4GB=64GB
> max. IOW PAE enables the use of 64GB max in a 32-bit architecture.
>
> Conclusion.
> Enable these switches as instructed and don't assume that one includes the
> other.
>
> "abckid" <abckid@discussions.microsoft.com> wrote in message
> news:8B1DBE78-7D39-4313-BAB9-3A044D88BD25@microsoft.com...
> > Hi,
> >
> > Due to some requirement for SAP in Win2K3 with 32-bit systems we have to
> > enable the /3GB option as per Microsoft KB article 283037.
> > In the article, it is mentioned about PAE switch. I want to know, is there
> > any difference between /PAE and /3GB options ? If i enable just /PAE in
> > Windows is it ok or i have to enable /3GB option as required ?
> >
> > Please guide. Thanks in advance.
> >
> > abckid.
>
>

 

Hi,

There is also something with AWE option. Please clearify that too ?

Thanks,

abc.

"abckid" wrote:

> Hi,
>
> Thanks for receptive reply.
>
> I have the note from SAP to first enable 3GB and then have mentioned in step
> 2 to Activate the 3 GB boot option according to Microsoft KB article 283037.
> I will copy the steps as below,
> ######################
> 1. The Windows Server operating system family (as of Windows 2000
> Advanced Server), a special boot option provides a 3 GB address space
> for each process. Programs that are to use this 3 GB address space
> must be prepared by a flag in program header. To do this, Windows must
> be installed again, or an already existing Windows version must be set
> up according to the Microsoft guidelines.
>
> 2. Activate the 3 GB boot option according to Microsoft KB article 283037.
> #######################
>
> They have just mentioned about 3GB, but also mentioned that we have to
> install windows again !!! We have system with 24GB of physical RAM. So i
> think /PAE should be used.
>
> Please guide more on this. Thanks again
>
> abckid.
>
> "Dusko Savatovic" wrote:
>
> > /PAE and /3GB are two different things.
> >
> > /3GB - in the original 32-bit architecture, the total address space is 4GB.
> > This was originaly divided in half. 2GB for OS and 2GB for apps. The 3GB
> > says that app can address max 3GB, leaving only 1GB for the OS.
> >
> > /PAE - When it became obvious that 4GB limit is going to be a problem, Intel
> > added 4 more address lines to it's processors, hence 2^4=16, 16*4GB=64GB
> > max. IOW PAE enables the use of 64GB max in a 32-bit architecture.
> >
> > Conclusion.
> > Enable these switches as instructed and don't assume that one includes the
> > other.
> >
> > "abckid" <abckid@discussions.microsoft.com> wrote in message
> > news:8B1DBE78-7D39-4313-BAB9-3A044D88BD25@microsoft.com...
> > > Hi,
> > >
> > > Due to some requirement for SAP in Win2K3 with 32-bit systems we have to
> > > enable the /3GB option as per Microsoft KB article 283037.
> > > In the article, it is mentioned about PAE switch. I want to know, is there
> > > any difference between /PAE and /3GB options ? If i enable just /PAE in
> > > Windows is it ok or i have to enable /3GB option as required ?
> > >
> > > Please guide. Thanks in advance.
> > >
> > > abckid.
> >
> >

 

The following applies to 32-bit Windows only.

1. If you have more than 4GB, you must use /PAE to make this memory
available to the system.

2. Windows applications were originaly written to use 2GB maximum. Some
applications, like Exchange 2000/2003 and SQL Server 2000 can benefit with
/3GB switch. With that switch, they can use up to 3GB.

3. AWE (Address Windowing Extensions) is a technology that enables
applications to use even more than 3GB. However, this memory space is not
linear (continous), so the application must map memory blocks which are
outside of the initial 4GB address space to the window inside the initial
4GB space. Of course, the application must be written in such a way to use
benefits offered by the AWE.

In short.

1. AFAIK, there is no need to reinstall Windows when you use /PAE and /3GB
options in your boot.ini

2. When you use /PAE, application is unaware of this option, it just gets
memory that it needs (up to 2GB).

3. When you use /3GB, application must be made aware of the fact that it can
now use up to 3GB. It is up to the application to detect this.

4. If the application wants to use even more memory, it must use AWE (this
is API). However, it may not use all the memory linearly (continously), but
it must map blocks of memory to the window that exists in the lower memory
space (below 4GB).

5. From the Microsoft KB article 283037
<quote>
....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.
</quote>
Ask your SAP consultants what they want. If they want both, your system will
use 16GB only.

64-bit technology does not have these limitations.

Good luck.



"abckid" <abckid@discussions.microsoft.com> wrote in message
news:FFA0D098-7AC3-4D26-8AEA-1B8D261E3E5D@microsoft.com...
> Hi,
>
> There is also something with AWE option. Please clearify that too ?
>
> Thanks,
>
> abc.
>
> "abckid" wrote:
>
>> Hi,
>>
>> Thanks for receptive reply.
>>
>> I have the note from SAP to first enable 3GB and then have mentioned in
>> step
>> 2 to Activate the 3 GB boot option according to Microsoft KB article
>> 283037.
>> I will copy the steps as below,
>> ######################
>> 1. The Windows Server operating system family (as of Windows 2000
>> Advanced Server), a special boot option provides a 3 GB address space
>> for each process. Programs that are to use this 3 GB address space
>> must be prepared by a flag in program header. To do this, Windows must
>> be installed again, or an already existing Windows version must be set
>> up according to the Microsoft guidelines.
>>
>> 2. Activate the 3 GB boot option according to Microsoft KB article
>> 283037.
>> #######################
>>
>> They have just mentioned about 3GB, but also mentioned that we have to
>> install windows again !!! We have system with 24GB of physical RAM. So i
>> think /PAE should be used.
>>
>> Please guide more on this. Thanks again
>>
>> abckid.
>>
>> "Dusko Savatovic" wrote:
>>
>> > /PAE and /3GB are two different things.
>> >
>> > /3GB - in the original 32-bit architecture, the total address space is
>> > 4GB.
>> > This was originaly divided in half. 2GB for OS and 2GB for apps. The
>> > 3GB
>> > says that app can address max 3GB, leaving only 1GB for the OS.
>> >
>> > /PAE - When it became obvious that 4GB limit is going to be a problem,
>> > Intel
>> > added 4 more address lines to it's processors, hence 2^4=16,
>> > 16*4GB=64GB
>> > max. IOW PAE enables the use of 64GB max in a 32-bit architecture.
>> >
>> > Conclusion.
>> > Enable these switches as instructed and don't assume that one includes
>> > the
>> > other.
>> >
>> > "abckid" <abckid@discussions.microsoft.com> wrote in message
>> > news:8B1DBE78-7D39-4313-BAB9-3A044D88BD25@microsoft.com...
>> > > Hi,
>> > >
>> > > Due to some requirement for SAP in Win2K3 with 32-bit systems we have
>> > > to
>> > > enable the /3GB option as per Microsoft KB article 283037.
>> > > In the article, it is mentioned about PAE switch. I want to know, is
>> > > there
>> > > any difference between /PAE and /3GB options ? If i enable just /PAE
>> > > in
>> > > Windows is it ok or i have to enable /3GB option as required ?
>> > >
>> > > Please guide. Thanks in advance.
>> > >
>> > > abckid.
>> >
>> >

 

<quote>
They have just mentioned about 3GB, but also mentioned that we have to
install windows again !!! We have system with 24GB of physical RAM. So i
think /PAE should be used.
</quote>

To my knowledge, it is not necessary to reinstall Windows when you use /PAE
or /3GB switches in boot.ini. Please ask your consultants to provide
evidence of this requirement.


"Dusko Savatovic" <nospam.savatovic@gmail.com> wrote in message
news:OW22FFt3JHA.1424@TK2MSFTNGP02.phx.gbl...
> The following applies to 32-bit Windows only.
>
> 1. If you have more than 4GB, you must use /PAE to make this memory
> available to the system.
>
> 2. Windows applications were originaly written to use 2GB maximum. Some
> applications, like Exchange 2000/2003 and SQL Server 2000 can benefit with
> /3GB switch. With that switch, they can use up to 3GB.
>
> 3. AWE (Address Windowing Extensions) is a technology that enables
> applications to use even more than 3GB. However, this memory space is not
> linear (continous), so the application must map memory blocks which are
> outside of the initial 4GB address space to the window inside the initial
> 4GB space. Of course, the application must be written in such a way to use
> benefits offered by the AWE.
>
> In short.
>
> 1. AFAIK, there is no need to reinstall Windows when you use /PAE and /3GB
> options in your boot.ini
>
> 2. When you use /PAE, application is unaware of this option, it just gets
> memory that it needs (up to 2GB).
>
> 3. When you use /3GB, application must be made aware of the fact that it
> can now use up to 3GB. It is up to the application to detect this.
>
> 4. If the application wants to use even more memory, it must use AWE (this
> is API). However, it may not use all the memory linearly (continously),
> but it must map blocks of memory to the window that exists in the lower
> memory space (below 4GB).
>
> 5. From the Microsoft KB article 283037
> <quote>
> ...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.
> </quote>
> Ask your SAP consultants what they want. If they want both, your system
> will use 16GB only.
>
> 64-bit technology does not have these limitations.
>
> Good luck.
>
>
>
> "abckid" <abckid@discussions.microsoft.com> wrote in message
> news:FFA0D098-7AC3-4D26-8AEA-1B8D261E3E5D@microsoft.com...
>> Hi,
>>
>> There is also something with AWE option. Please clearify that too ?
>>
>> Thanks,
>>
>> abc.
>>
>> "abckid" wrote:
>>
>>> Hi,
>>>
>>> Thanks for receptive reply.
>>>
>>> I have the note from SAP to first enable 3GB and then have mentioned in
>>> step
>>> 2 to Activate the 3 GB boot option according to Microsoft KB article
>>> 283037.
>>> I will copy the steps as below,
>>> ######################
>>> 1. The Windows Server operating system family (as of Windows 2000
>>> Advanced Server), a special boot option provides a 3 GB address space
>>> for each process. Programs that are to use this 3 GB address space
>>> must be prepared by a flag in program header. To do this, Windows must
>>> be installed again, or an already existing Windows version must be set
>>> up according to the Microsoft guidelines.
>>>
>>> 2. Activate the 3 GB boot option according to Microsoft KB article
>>> 283037.
>>> #######################
>>>
>>> They have just mentioned about 3GB, but also mentioned that we have to
>>> install windows again !!! We have system with 24GB of physical RAM. So i
>>> think /PAE should be used.
>>>
>>> Please guide more on this. Thanks again
>>>
>>> abckid.
>>>
>>> "Dusko Savatovic" wrote:
>>>
>>> > /PAE and /3GB are two different things.
>>> >
>>> > /3GB - in the original 32-bit architecture, the total address space is
>>> > 4GB.
>>> > This was originaly divided in half. 2GB for OS and 2GB for apps. The
>>> > 3GB
>>> > says that app can address max 3GB, leaving only 1GB for the OS.
>>> >
>>> > /PAE - When it became obvious that 4GB limit is going to be a problem,
>>> > Intel
>>> > added 4 more address lines to it's processors, hence 2^4=16,
>>> > 16*4GB=64GB
>>> > max. IOW PAE enables the use of 64GB max in a 32-bit architecture.
>>> >
>>> > Conclusion.
>>> > Enable these switches as instructed and don't assume that one includes
>>> > the
>>> > other.
>>> >
>>> > "abckid" <abckid@discussions.microsoft.com> wrote in message
>>> > news:8B1DBE78-7D39-4313-BAB9-3A044D88BD25@microsoft.com...
>>> > > Hi,
>>> > >
>>> > > Due to some requirement for SAP in Win2K3 with 32-bit systems we
>>> > > have to
>>> > > enable the /3GB option as per Microsoft KB article 283037.
>>> > > In the article, it is mentioned about PAE switch. I want to know, is
>>> > > there
>>> > > any difference between /PAE and /3GB options ? If i enable just /PAE
>>> > > in
>>> > > Windows is it ok or i have to enable /3GB option as required ?
>>> > >
>>> > > Please guide. Thanks in advance.
>>> > >
>>> > > abckid.
>>> >
>>> >
>

 

Hi,

Thank you very much your reply.

You have mentioned - with /PAE option, we can use more than 4GB memory (upto
64GB)

Also its mentioned - "2. When you use /PAE, application is unaware of this
option, it just gets memory that it needs (up to 2GB)."

A bit confused with (up to 2GB) thing. With /PAE application can access more
that 2GB, right ?

Thanks,

abc

"Dusko Savatovic" wrote:

> <quote>
> They have just mentioned about 3GB, but also mentioned that we have to
> install windows again !!! We have system with 24GB of physical RAM. So i
> think /PAE should be used.
> </quote>
>
> To my knowledge, it is not necessary to reinstall Windows when you use /PAE
> or /3GB switches in boot.ini. Please ask your consultants to provide
> evidence of this requirement.
>
>
> "Dusko Savatovic" <nospam.savatovic@gmail.com> wrote in message
> news:OW22FFt3JHA.1424@TK2MSFTNGP02.phx.gbl...
> > The following applies to 32-bit Windows only.
> >
> > 1. If you have more than 4GB, you must use /PAE to make this memory
> > available to the system.
> >
> > 2. Windows applications were originaly written to use 2GB maximum. Some
> > applications, like Exchange 2000/2003 and SQL Server 2000 can benefit with
> > /3GB switch. With that switch, they can use up to 3GB.
> >
> > 3. AWE (Address Windowing Extensions) is a technology that enables
> > applications to use even more than 3GB. However, this memory space is not
> > linear (continous), so the application must map memory blocks which are
> > outside of the initial 4GB address space to the window inside the initial
> > 4GB space. Of course, the application must be written in such a way to use
> > benefits offered by the AWE.
> >
> > In short.
> >
> > 1. AFAIK, there is no need to reinstall Windows when you use /PAE and /3GB
> > options in your boot.ini
> >
> > 2. When you use /PAE, application is unaware of this option, it just gets
> > memory that it needs (up to 2GB).
> >
> > 3. When you use /3GB, application must be made aware of the fact that it
> > can now use up to 3GB. It is up to the application to detect this.
> >
> > 4. If the application wants to use even more memory, it must use AWE (this
> > is API). However, it may not use all the memory linearly (continously),
> > but it must map blocks of memory to the window that exists in the lower
> > memory space (below 4GB).
> >
> > 5. From the Microsoft KB article 283037
> > <quote>
> > ...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.
> > </quote>
> > Ask your SAP consultants what they want. If they want both, your system
> > will use 16GB only.
> >
> > 64-bit technology does not have these limitations.
> >
> > Good luck.
> >
> >
> >
> > "abckid" <abckid@discussions.microsoft.com> wrote in message
> > news:FFA0D098-7AC3-4D26-8AEA-1B8D261E3E5D@microsoft.com...
> >> Hi,
> >>
> >> There is also something with AWE option. Please clearify that too ?
> >>
> >> Thanks,
> >>
> >> abc.
> >>
> >> "abckid" wrote:
> >>
> >>> Hi,
> >>>
> >>> Thanks for receptive reply.
> >>>
> >>> I have the note from SAP to first enable 3GB and then have mentioned in
> >>> step
> >>> 2 to Activate the 3 GB boot option according to Microsoft KB article
> >>> 283037.
> >>> I will copy the steps as below,
> >>> ######################
> >>> 1. The Windows Server operating system family (as of Windows 2000
> >>> Advanced Server), a special boot option provides a 3 GB address space
> >>> for each process. Programs that are to use this 3 GB address space
> >>> must be prepared by a flag in program header. To do this, Windows must
> >>> be installed again, or an already existing Windows version must be set
> >>> up according to the Microsoft guidelines.
> >>>
> >>> 2. Activate the 3 GB boot option according to Microsoft KB article
> >>> 283037.
> >>> #######################
> >>>
> >>> They have just mentioned about 3GB, but also mentioned that we have to
> >>> install windows again !!! We have system with 24GB of physical RAM. So i
> >>> think /PAE should be used.
> >>>
> >>> Please guide more on this. Thanks again
> >>>
> >>> abckid.
> >>>
> >>> "Dusko Savatovic" wrote:
> >>>
> >>> > /PAE and /3GB are two different things.
> >>> >
> >>> > /3GB - in the original 32-bit architecture, the total address space is
> >>> > 4GB.
> >>> > This was originaly divided in half. 2GB for OS and 2GB for apps. The
> >>> > 3GB
> >>> > says that app can address max 3GB, leaving only 1GB for the OS.
> >>> >
> >>> > /PAE - When it became obvious that 4GB limit is going to be a problem,
> >>> > Intel
> >>> > added 4 more address lines to it's processors, hence 2^4=16,
> >>> > 16*4GB=64GB
> >>> > max. IOW PAE enables the use of 64GB max in a 32-bit architecture.
> >>> >
> >>> > Conclusion.
> >>> > Enable these switches as instructed and don't assume that one includes
> >>> > the
> >>> > other.
> >>> >
> >>> > "abckid" <abckid@discussions.microsoft.com> wrote in message
> >>> > news:8B1DBE78-7D39-4313-BAB9-3A044D88BD25@microsoft.com...
> >>> > > Hi,
> >>> > >
> >>> > > Due to some requirement for SAP in Win2K3 with 32-bit systems we
> >>> > > have to
> >>> > > enable the /3GB option as per Microsoft KB article 283037.
> >>> > > In the article, it is mentioned about PAE switch. I want to know, is
> >>> > > there
> >>> > > any difference between /PAE and /3GB options ? If i enable just /PAE
> >>> > > in
> >>> > > Windows is it ok or i have to enable /3GB option as required ?
> >>> > >
> >>> > > Please guide. Thanks in advance.
> >>> > >
> >>> > > abckid.
> >>> >
> >>> >
> >
>
>

 

"abckid" <abckid@discussions.microsoft.com> wrote in message
news:3736A42B-7C3A-455C-922F-AC9BF104D850@microsoft.com...
> Hi,
>
> Thank you very much your reply.
>
> You have mentioned - with /PAE option, we can use more than 4GB memory
> (upto
> 64GB)
>
> Also its mentioned - "2. When you use /PAE, application is unaware of this
> option, it just gets memory that it needs (up to 2GB)."
>
> A bit confused with (up to 2GB) thing. With /PAE application can access
> more
> that 2GB, right ?

Nope, the whole system can access up to 4GB without /PAE and up to 64 GB
with /PAE.
The whole system = OS + Hardware + Applications.

Remember, the system was initially designed so that OS + Hardware get half
(up to 2GB), and applications get the other half, up to 2GB.
/3GB switch changes this ratio to: OS + Hardware = 1GB, Applications = 3GB.
Let's stick with /PAE (without /3GB).
The application still gets up to 2GB. But in your scenario, you can have
have up to 11 applications, each getting 2GB which equals 22GB.
22GB + 2GB (OS + Hardware) = 24 GB (your current amount of memory).

If you want that your application accesses more than 2GB of memory, the
application must use AWE API. However, the memory above 2 GB is not directly
(lineary) accessible. It must be switched into the address space (window)
below 2GB. For example, Microsoft SQL Server 2000 is using AWE to process
database data pages directly in memory. OTOH, the team that designed
Microsoft Exchange 2007 decided that they are not going to do any acrobatics
with AWE, so they required 64-bit OS for production servers right from the
start.

> Thanks,
Welcome

 

Hi,

Now it's clear about /PAE switch. So each application is still limited to
2GB, but having multiple application, they do not have to share 2GB but can
have access upto 2GB each from the available memory.

We have clustered Win2K3-R2 Ent. servers running SQL 2005. After i enabled
the /3GB switch (as informed by SAP) and restart the server, the application
was not coming up (This is SAP issue). Also noted was the cluster was also
not coming up properly sometimes.

Just wanted to know, does /3GB option have any issues with Clusterd Win2K3 +
SQL 2005 ?

This is a seperate problem, i hope you can guide on this.

Thanks,

abc.

"Dusko Savatovic" wrote:

>
> "abckid" <abckid@discussions.microsoft.com> wrote in message
> news:3736A42B-7C3A-455C-922F-AC9BF104D850@microsoft.com...
> > Hi,
> >
> > Thank you very much your reply.
> >
> > You have mentioned - with /PAE option, we can use more than 4GB memory
> > (upto
> > 64GB)
> >
> > Also its mentioned - "2. When you use /PAE, application is unaware of this
> > option, it just gets memory that it needs (up to 2GB)."
> >
> > A bit confused with (up to 2GB) thing. With /PAE application can access
> > more
> > that 2GB, right ?
>
> Nope, the whole system can access up to 4GB without /PAE and up to 64 GB
> with /PAE.
> The whole system = OS + Hardware + Applications.
>
> Remember, the system was initially designed so that OS + Hardware get half
> (up to 2GB), and applications get the other half, up to 2GB.
> /3GB switch changes this ratio to: OS + Hardware = 1GB, Applications = 3GB.
> Let's stick with /PAE (without /3GB).
> The application still gets up to 2GB. But in your scenario, you can have
> have up to 11 applications, each getting 2GB which equals 22GB.
> 22GB + 2GB (OS + Hardware) = 24 GB (your current amount of memory).
>
> If you want that your application accesses more than 2GB of memory, the
> application must use AWE API. However, the memory above 2 GB is not directly
> (lineary) accessible. It must be switched into the address space (window)
> below 2GB. For example, Microsoft SQL Server 2000 is using AWE to process
> database data pages directly in memory. OTOH, the team that designed
> Microsoft Exchange 2007 decided that they are not going to do any acrobatics
> with AWE, so they required 64-bit OS for production servers right from the
> start.
>
> > Thanks,
> Welcome
>
>

 

On Thu, 28 May 2009 10:13:29 +0200, "Dusko Savatovic"
<nospam.savatovic@gmail.com> wrote:

Thanks for explaining this, I have been confused for ever about these options
but it all makes sense now. Thanks again.
--
Dave Mills
There are 10 types of people, those that understand binary and those that don't.

 

Sorry abckid,

I do understand just about as much as I need about SQL Server, but I would
not dare give you advices in that department. I'm sure that there are many
competent posters on SQL Server forums and newsgroups.

I may advise you to ask for more help from your SAP consultants. SAP is
expensive and complex system and I'm sure that you are entitled for good
quality service.

Good luck

"abckid" <abckid@discussions.microsoft.com> wrote in message
newsBB2C685-CF3D-4FB3-9995-3177218A8855@microsoft.com...
> Hi,
>
> Now it's clear about /PAE switch. So each application is still limited to
> 2GB, but having multiple application, they do not have to share 2GB but
> can
> have access upto 2GB each from the available memory.
>
> We have clustered Win2K3-R2 Ent. servers running SQL 2005. After i enabled
> the /3GB switch (as informed by SAP) and restart the server, the
> application
> was not coming up (This is SAP issue). Also noted was the cluster was also
> not coming up properly sometimes.
>
> Just wanted to know, does /3GB option have any issues with Clusterd Win2K3
> +
> SQL 2005 ?
>
> This is a seperate problem, i hope you can guide on this.
>
> Thanks,
>
> abc.
>
> "Dusko Savatovic" wrote:
>
>>
>> "abckid" <abckid@discussions.microsoft.com> wrote in message
>> news:3736A42B-7C3A-455C-922F-AC9BF104D850@microsoft.com...
>> > Hi,
>> >
>> > Thank you very much your reply.
>> >
>> > You have mentioned - with /PAE option, we can use more than 4GB memory
>> > (upto
>> > 64GB)
>> >
>> > Also its mentioned - "2. When you use /PAE, application is unaware of
>> > this
>> > option, it just gets memory that it needs (up to 2GB)."
>> >
>> > A bit confused with (up to 2GB) thing. With /PAE application can access
>> > more
>> > that 2GB, right ?
>>
>> Nope, the whole system can access up to 4GB without /PAE and up to 64 GB
>> with /PAE.
>> The whole system = OS + Hardware + Applications.
>>
>> Remember, the system was initially designed so that OS + Hardware get
>> half
>> (up to 2GB), and applications get the other half, up to 2GB.
>> /3GB switch changes this ratio to: OS + Hardware = 1GB, Applications =
>> 3GB.
>> Let's stick with /PAE (without /3GB).
>> The application still gets up to 2GB. But in your scenario, you can have
>> have up to 11 applications, each getting 2GB which equals 22GB.
>> 22GB + 2GB (OS + Hardware) = 24 GB (your current amount of memory).
>>
>> If you want that your application accesses more than 2GB of memory, the
>> application must use AWE API. However, the memory above 2 GB is not
>> directly
>> (lineary) accessible. It must be switched into the address space (window)
>> below 2GB. For example, Microsoft SQL Server 2000 is using AWE to process
>> database data pages directly in memory. OTOH, the team that designed
>> Microsoft Exchange 2007 decided that they are not going to do any
>> acrobatics
>> with AWE, so they required 64-bit OS for production servers right from
>> the
>> start.
>>
>> > Thanks,
>> Welcome
>>
>>