Friday, 25 June 2010

Lock Pages in Memory

It is generally recommended that 'lock pages in memory' be enabled for your SQL Servers to prevent the OS paging out SQL Server memory.

how do you do this?

Well, the answer is straight forward...If you have SQL Server Enterprise Edition:

You allocate the service account running SQL Server the 'Lock Pages In Memory' permission.

How Can I Tell if 'Lock Pages in Memory is Enabled?'


I am using Windows 2003 R2 and SQL Server 2008 SP1 for this demo but I have also done this on Windows 2008 R2 and it works just the same way. It is a 64 bit environment.

If you are running SQL Server with the Local System account, I know most of you are not, but for those of you that are, SQL Server will automatically 'lock pages in memory'. Bob Ward has a blog post on this here: (

If you are using the local system or a domain account with appropriate permissions you will see an entry similar to the following at the start of the SQL Server log:


Therefore if you are running SQL Server using a domain account and the domain account does not have the necessary permissions to lock pages in memory then you will not have this message in the log:


If you do not have 'Lock Pages In Memory' enabled and you would like too enable it then follow these steps:

Logon to the SQL Server in question

Click <Start><Run> and enter 'secpol.msc' in the run box.

In the 'Local Security Policy' window that opens expand <Local Policies> and <User Rights Assignment> in the left hand pane.


In the right hand pain scroll down to the 'lock pages in memory' policy. Right Click, select <Properties> <Add User or Group> and add the domain account that is running the SQL Service and click <OK>


That's it, you need to restart the SQL Server service for the change to take effect, the next time that SQL Server starts up you should see


in the SQL Server log.

Standard Edition

Up until SQL Server 2005 SP3 Cumulative Update Package 4 and SQL Server 2008 SP1 Cumulative Update Package 2 'Lock Pages in Memory' was not supported in SQL Server Standard Edition.

You may find this link helpful

as you need to request the CUs from Microsoft. They will then send you a link to download the CU.

These two CUs add the 'lock pages in memory' option for SQL Server Standard edition.

Note you you have to enable trace flag 845 to for standard edition to be able to 'lock pages in memory.'

Virtualisation, SQL Server and Lock Pages

Are you running SQL Server in Virtual Land, well here is something else to to consider care of Mr Denny:

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