Configuring the maximum memory for audit store databases

Because Microsoft SQL Server uses physical memory to hold database information for fast query results, you should use a dedicated instance to store auditing data. Because SQL Server dynamically acquires memory whenever it needs it until it reaches the maximum server memory you have configured, you should set constraints on how much physical memory it should be allowed to consume.

The maximum server memory (max server memory) setting controls the maximum amount of physical memory that can be consumed by the Microsoft SQL Server buffer pool. The default value for this setting is such a high number that the default maximum server memory is virtually unlimited. Because of this default value, SQL Server will try to consume as much memory as possible to improve query performance by caching data in memory.

Processes that run outside SQL Server, such as operating system processes, thread stacks, socket connections and Common Language Runtime (CLR) stored procedures are not allowed to use the memory allocated to the Microsoft SQL Server buffer pool. Because those other processes can only use the remaining available memory, they might not have enough physical memory to perform their operations. In most casts, the lack of physical memory forces the operating system to read and write to disk frequently and reduces overall performance.

To prevent Microsoft SQL Server from consuming too much memory, you can use the following formula to determine the recommended maximum server memory:

  • Reserve 4GB from the first 16GB of RAM and then 1GB from each additional 8GB of RAM for the operating system and other applications.
  • Configure the remaining memory as the maximum server memory allocated for the Microsoft SQL Server buffer pool.

For example, if the computer hosting the Microsoft SQL Server instance has 32GB of total physical memory, you would reserve 4 GB (from first 16 GB) + 1GB (from next 8 GB) + 1 GB (from next 8 GB) for the operating system, then set the Maximum server memory for Microsoft SQL server to 26 GB (32 GB – 4 GB – 1 GB – 1 GB = 26).

For more information about how to configure Microsoft SQL Server maximum memory setting and other memory options, see the following Microsoft article: https://docs.microsoft.com/en-us/previous-versions/sql/sql-server-2008-r2/ms178067(v=sql.105)

You should configure the maximum memory allowed for the Microsoft SQL Server instances hosting audit store databases and the management database. However, this setting is especially important to configure on the Microsoft SQL Server instance hosting the active audit store database.