Server RAM limitations 1

[wbodger]

So, I was talking with a friend that works for MS and he was positing that within the MS OS, it could not address more than like 8Gb of RAM within a 32 bit OS, so adding any more RAM than that was useless. Was he just referring to the OS, because it seems to me that everything I have seen states that SQL Server can utilize more RAM than just 8 gb?

 

[JayKusch]

What version of SQL are we talking?

Thanks

J. Kusch

 

[JayKusch]

2005:
Express Edition x86 = 1GB
Workgroup Edition x86 = 3GB
Standard Edition x86 = os limit
Standard Edition x64 = 32TB
Developer Edition x86 = os limit
Developer Edition x64 = 32TB
Enterprise Edition x86, x64 = os limit
Datacenter Edition x86, x64 = os limit


Thanks

J. Kusch

 

[wbodger]

So, what about the OS limits? in my case we are still on SQL 2K Enterprise Edition. Windows Server 2003, x86.

 

[mutley1]

Have a look at

http://support.microsoft.com/kb/274750

and also check out "Managing AWE Memory" in BOL. We currently have 16GB in the box with AWE and PAE switch set.

We did, however, have to install an MS hotfix for it to start using the memory as it didn't pick it up. Sorry, but I can't find the post I made to this forum or the hotfix number, but it worked after that.....

HTH,

M.

 

[mutley1]

Found the hotfix. We are also running SQL 2K EE on a cluster.

http://support.microsoft.com/kb/899761

HTH,

M.

 

[wbodger]

Great, thanks!

 

[SQLWilts]

One word of warning - you have to use a different combination of switches if you have more than 16GB in your server - Windoze needs more at the base to manage the OS...

Can't find it now, but there are numerous postings on the subject

 

[mutley1]

Wilts,

Would you be able to point me in the right direction with switch combos. We have just got a server with 32GB and it would be nice to top the 16GB usage....

TIA,

M.

 

[SQLWilts]

Hi Mutley,

Quote from the KB site below:

Typically, a process running under Windows 2000 or Windows Server 2003 can access up to 2 GB of memory address space (assuming the /3GB switch was not used) with some of the memory being physical memory and some being virtual memory. The more programs (and, therefore, more processes) that run, the more memory you commit up to the full 2 GB of address space.

When this situation occurs, the paging process increases dramatically and performance may be negatively impacted. The Windows 2000 and Windows Server 2003 memory managers use PAE to provide more physical memory to a program. This reduces the need to swap the memory of the page file and results in increased performance. The program itself is not aware of the actual memory size. All the memory management and allocation of the PAE memory is handled by the memory manager independently of the programs that run.

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.

http://support.microsoft.com/kb/283037

HTH

 

[mutley1]

Thanks Wilts!

 

[SQLWilts]

welcome