Mar 282012
 

Oracle has a strange bit of behavior when you explicitly enable Large Pages and force the Oracle database to be NUMA-aware: it either won’t start up or it disables the NUMA-awareness.

Does SQL Server disable one or the other if you have a NUMA-aware instance with Large Pages enabled?

 Posted by at 2:49 pm

  One Response to “SQL Server Large Pages + NUMA aware = no NUMA or no Large Pages?”

  1. Hi David, I just ran across your blog, and nobody else seems to have commented, so I thought I might offer this:

    SQL Server does not disable either. On startup, if large pages are available, it allocates a large page for each memory (NUMA) node (ref: <a href="http://blogs.msdn.com/b/psssql/archive/2009/06/05/sql-server-and-large-pages-explained.aspx&quot; title="CSS Blog: SQL Server and Large Pages Explained…" )

    Here's a snippet from the errorlog on one of my servers that does run in this configuration:

    2012-04-04 23:31:55.13 Server Large Page Extensions enabled.
    2012-04-04 23:31:55.13 Server Large Page Granularity: 2097152
    2012-04-04 23:31:55.31 Server Large Page Allocated: 32MB
    2012-04-04 23:31:55.47 Server Large Page Allocated: 32MB
    2012-04-04 23:31:55.56 Server Large Page Allocated: 32MB
    2012-04-04 23:31:55.63 Server Large Page Allocated: 32MB
    2012-04-04 23:31:55.73 Server Large Page Allocated: 32MB
    2012-04-04 23:31:55.80 Server Large Page Allocated: 32MB
    2012-04-04 23:31:56.26 Server Large Page Allocated: 32MB
    2012-04-04 23:31:56.29 Server Large Page Allocated: 32MB

    2012-04-04 23:31:59.44 Server Node configuration: node 0: CPU mask: 0x000000000000ff00:0 Active CPU mask: 0x000000000000ff00:0. This message provides a description of the NUMA configuration for this computer. This is an informational message only. No user action is required.
    2012-04-04 23:31:59.44 Server Node configuration: node 1: CPU mask: 0x00000000000000ff:0 Active CPU mask: 0x00000000000000ff:0. This message provides a description of the NUMA configuration for this computer. This is an informational message only. No user action is required.
    2012-04-04 23:31:59.44 Server Node configuration: node 2: CPU mask: 0x0000000000ff0000:0 Active CPU mask: 0x0000000000ff0000:0. This message provides a description of the NUMA configuration for this computer. This is an informational message only. No user action is required.
    2012-04-04 23:31:59.44 Server Node configuration: node 3: CPU mask: 0x00000000ff000000:0 Active CPU mask: 0x00000000ff000000:0. This message provides a description of the NUMA configuration for this computer. This is an informational message only. No user action is required.
    2012-04-04 23:31:59.44 Server Node configuration: node 4: CPU mask: 0x000000ff00000000:0 Active CPU mask: 0x000000ff00000000:0. This message provides a description of the NUMA configuration for this computer. This is an informational message only. No user action is required.
    2012-04-04 23:31:59.44 Server Node configuration: node 5: CPU mask: 0x0000ff0000000000:0 Active CPU mask: 0x0000ff0000000000:0. This message provides a description of the NUMA configuration for this computer. This is an informational message only. No user action is required.
    2012-04-04 23:31:59.44 Server Node configuration: node 6: CPU mask: 0x00ff000000000000:0 Active CPU mask: 0x00ff000000000000:0. This message provides a description of the NUMA configuration for this computer. This is an informational message only. No user action is required.
    2012-04-04 23:31:59.44 Server Node configuration: node 7: CPU mask: 0xff00000000000000:0 Active CPU mask: 0xff00000000000000:0. This message provides a description of the NUMA configuration for this computer. This is an informational message only. No user action is required.