March 20, 2003 at 9:09 am
I have a server with 3.6 gigs of ram. This server is intermittantly experiencing a lot of paging - hundreds of pages per second. It does not have AWE enabled and has SQL Enterprise edition installed. It has hardware raid 5 and 4 processors. The users (Human Resources) have not complained about performance, but a new web application will be available soon for all employees to check their own records, so usage will increase.
I don't have any experience with AWE, and I am confused about what I am reading. Does a server have to have 4 gigs of ram to take advantage of AWE?
An immediate issue is that this particular server has the wrong edition of SQL installed on it. We have a license for Enterprise, but it really is supposed to be installed on another server being built in couple of weeks. I need to figure out if it is worth it to go ahead and buy the Enterprise Edition for this server. If AWE can not be used with less than 4 gigs, then it makes more sense to go with Standard Edition.
Thanks,
Kathi
Aunt Kathi Data Platform MVP
Author of Expert T-SQL Window Functions
Simple-Talk Editor
March 20, 2003 at 9:25 am
I just had an idea about this.
Maybe SQL has too much memory. The memory is dynamically configured and the "Total Server Memory" counter is at 1.6 gigs. So, Windows only has .4 gigs to use. Maybe if I set the maximum memory lower (maybe 1 gig) the server would stop paging.
I'm pretty new to performance tuning, so let me know if it sounds like I'm on the right track.
Thanks,
Kathi
Aunt Kathi Data Platform MVP
Author of Expert T-SQL Window Functions
Simple-Talk Editor
March 20, 2003 at 11:29 am
You said the server has 3.6 GB RAM.If SQL uses 1.6 GB then Windows would have 2 GB, or am I missing something? I would advice you to stick with Standard Edition and not use AWE but instead use the 3 GB switch to let SQL Server use 3 GB mamory and leave the rest for Windows. If there are no other applications on the server this should definately be enough.
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Chris Hedgate @ Apptus Technologies (http://www.apptus.se)
March 20, 2003 at 12:54 pm
You want SQL to have as much memory as possible. With 4g you should just use /3GB in the boot.ini, no need for AWE. That gives SQL 3g, 1g for the OS (more than it needs, but no way to change).
Andy
March 20, 2003 at 3:01 pm
I'm even more confused on this now. I thought that the 3 gig switch was part of AWE since it is discussed in the BOL article "Using AWE Memory on Windows 2000".
OK, so AWE is only for memory over 4, I've got that straight now.
But, Standard Edition will only up to 2 gigs, correct?
Thanks,
Kathi
Aunt Kathi Data Platform MVP
Author of Expert T-SQL Window Functions
Simple-Talk Editor
March 20, 2003 at 4:11 pm
Normally yes, because the memory on a Windows machine is managed in such a way that applications share the first 2 GB, while the OS uses the last 2 GB of RAM. But if you start Windows with the /3GB switch (by editing boot.ini) SQL Server and all other applications of course will have 3 GB of RAM to use, and the OS will have only 1 GB (which is a lot more than it needs anyway).
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Chris Hedgate @ Apptus Technologies (http://www.apptus.se)
March 20, 2003 at 5:36 pm
Great, sounds like Standard edition is the way to go.
Will the /3gb switch really do anything if there are 3.6 gigs not 4? Will it help the excessive paging?
Oh, by the way, thanks a bunch Andy and Chris for your help with this.
Kathi
Aunt Kathi Data Platform MVP
Author of Expert T-SQL Window Functions
Simple-Talk Editor
March 21, 2003 at 1:25 am
It should, because as I said, Windows don't really need more than that half gigabyte it will get (instead of 1.6 GB without the /3GB switch). However, if you are running SQL Server with memory configured dynamically, and you are seeing a lot of paging, that seems to show that there is something else running on the server. SQL Server normally never uses oaging, and if there is paging going on then SQL Server will automatically (if you're running dynamic mem config) reduce it's memory usage so that other applications -- which are probably the source of the paging -- can use more memory.
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Chris Hedgate @ Apptus Technologies (http://www.apptus.se)
March 21, 2003 at 8:13 am
Yes, there are other things going on. It has some PeopleSoft scheduled tasks running. I can see in the log that SQL is releasing a little bit of memory when the paging occurs.
Thanks for all of your help,
Kathi
Aunt Kathi Data Platform MVP
Author of Expert T-SQL Window Functions
Simple-Talk Editor
March 24, 2003 at 7:24 am
I found this very interesting as it's a problem I'm facing. Just thought it important to note that in order to use the /3GB swith, you must be running Windows Advanced Server. See the following:
http://support.microsoft.com/default.aspx?scid=kb%3Ben-us%3B274750
http://support.microsoft.com/default.aspx?scid=kb;EN-US;291988
John
March 24, 2003 at 8:03 am
Yes, that is true. We are running Advanced Server.
Aunt Kathi Data Platform MVP
Author of Expert T-SQL Window Functions
Simple-Talk Editor
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