Tag: GAM Interval

• Differential Changed Map (DCM): How SQL Server Tracks Changed Pages

  

  2014-05-07 - Backup, General, Series, SQL Server Internals, Storage Wednesday

  SQL Server uses the Differential Changed Map to determine, which pages changed since the last full backup. Read on to find out how the DCM is working.

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• The Shared Global Allocation Map (SGAM)

  

  2014-04-23 - General, Series, SQL Server Internals, Storage Wednesday

  Discover how SQL Server tracks mixed extents containing free pages using a Shared Global Allocation Map made up of one SGAM page per GAM Interval.

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• The Global Allocation Map (GAM)

  

  2014-04-16 - General, Series, SQL Server Internals, Storage Wednesday

  SQL Server uses the Global Allocation Map (GAM) to catalog if an extent is allocated or not. In a 7988-byte bitmap each extent is associated with a single bit to convey that information. Read on to get all the details.

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• The GAM Interval and GAM Extents

  

  2014-04-09 - General, Series, SQL Server Internals, Storage Wednesday

  What is a GAM extent in SQL Server? What is a GAM Interval and how big is it really? Read on now to get the answers to these questions and see why a GAM interval is not 64000 extents.

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