Microsoft KB Archive/168697

= INF: Estimating the Initial SQL Server Memory Setting =

Article ID: 168697

Article Last Modified on 3/1/2005

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APPLIES TO


 * Microsoft SQL Server 6.5 Standard Edition

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This article was previously published under Q168697



SUMMARY
The following equation provides a way to estimate what the initial SQL Server memory setting should be on a computer that is dedicated solely to SQL Server.

y=(.95x-22)*512

In the equation above, 'y' is the sp_configure memory setting in 2-KB pages and 'x' is the amount of RAM on the computer in MB. You can effectively use this equation on computers that have an amount of RAM ranging from 64 MB to 2 GB. On smaller systems, using a ratio of the values in the table below will provide a more accurate recommended configuration setting.



MORE INFORMATION
From the Systems Administration for Microsoft SQL Server 6.5 Student Workbook, the following data is provided for a start in allocating memory to SQL Server:

Physical RAM on a computer dedicated to SQL Server      Memory dedicated to       sp_configure 'memory' (MB) {x}       SQL Server (MB) {y}       setting (in 2-KB pages) ---  16                5.468                 2,800 (minimum, not recommended) 24                 8                   4,096 (SQL Server 6.5 default) 32                16                   8,192   48                 28                  14,336   64                 40                  20,480  128                100                  51,200  256                216                 110,592  512                464                 237,568

Using Excel Linear Regression capability, the last four values can be used to generate slope and intercepts for a best-fit line of the form y = mx+b. In this case, m = .9462 and b = (-22.09). For this purpose, .95 and (-22) will suffice, and the equation becomes y = (0.95)*x-22.

Thus, the appropriate SQL Server memory setting in MB is: (0.95)*(the amount of physical RAM on the computer, in MB) - 22.

Because the SQL Server memory setting is specified in 2-KB pages (for example, 2,048 bytes) and because 1 MB equals 1,048,576 bytes, the conversion factor from MB to 2-KB pages is (1,048,576/2,048) = 512 (2-KB pages/MB), the following equation delivers is the result:

The appropriate SQL Server sp_configure memory setting in 2-KB pages is: (((0.95)*(the amount of physical RAM on the computer, in MB) - 22)*512).

That is, y = (.95x-22)*512