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Basic Memory Question - > 2147483647 2g limit? Or.is it even enabled? Expand / Collapse
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Posted Friday, February 13, 2009 11:14 AM
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I have a question regarding the memory settings. I have new installs of 64bit sql server, and when I just do a default install, the Properties > Memory settings have a panel that has a checkbox to use AWE to allocate memory, and then 2 numeric boxes below, one with zero and one with 2147483647. My question is, Are the 2 boxes with the numbers related to the AWE checkbox, and is this what's used to limit the memory allocation? The reason is that this particular box is a VMWare install, and has 32g of memory allocated. There are 4 instances of SQL Server running here. Can I limit the memory used by the 4 instances, or should I just leave it and let it take what it needs. There seems to be plenty available as the instances are separated for a variety of requirements, but performance/load isn't one of them. Or should I enable this feature and just set each instance to max out at something below 8g?
Thanks for any insight


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Post #656856
Posted Monday, February 16, 2009 3:33 AM
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You don't need to switch on AWE. However it is recommended you grant the SQL
service account the "Lock Pages in Memory" right (you can do this by going
to Start>Programs>Administrative Tools>Local Security Policy and expanding
Local Policies>User Rights Assignment). For more details see
http://blogs.msdn.com/slavao/archive/2005/11/15/493019.aspx

Also, to keep memory usage under control by each instance set max server memory parameter under sp_configure.

MJ
Post #657564
Posted Tuesday, February 17, 2009 4:08 AM
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It is important to set the maximum memory limit for 64-bit SQL Server. The memory reported as available to SQL Server includes the page file size, so if you have a page file then SQL Server will try to use it as part of its memory pool. You are then looking at what should be memory to memory transfers being disk to memory, which will badly hurt your performance.

When deciding how much memory to allocate to SQL Server, you must first take out what is needed by Windows, Anti-Virus, file cache, and other components that are always running. You can divide the rest up between your SQL instances. If they are all of the same importance, give them all the same memory. Otherwise give the most important instances the most memory.


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Post #658352
Posted Wednesday, February 18, 2009 7:47 AM
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I'd set the max on each instance to total up to about 2.5 gig less than the total RAM installed. On our 64 bit servers, (single instance) it seems that with max RAM set to 13.5 Gig the peak still gets up close to 16 Gig.

And I'd firmly echo the thought that 64 bit installs need the lock pages in memory setting for the account running SQL Server. Failing to do that on one machine left me with intermittant "slow to a crawl" episodes as windows decided to page out sql server from time to time.



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Post #659402
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