“As per MSDN, the maximum memory can be consumed by SQL Server is 8TB, Will SQL Server surely use 8TB if the box is configured with 8TB?”. This was a question raised by an enthusiast.
“It will, but currently it is impossible”. It was my answer. Do you agree with me? Let me explain.
Virtual Address Memory, which is called as VAS refers the total amount of memory can be used by a Windows process or an application such as SQL Server. The size of the VAS varies according the to processor architecture (32-bit or 64-bit) and the edition of the operating system. If the processor architecture is 32-bit, VAS is 4GB. Under standard installation, 2GB is reserved for the system (kernel mode address space) and 2GB is reserved for the application (user mode address space). This proportion can be changed by adding a /3GB switch to the boot.ini for setting 3GB for user mode address space.
This is bit different when a 32-bit version of SQL Server is installed on 64-bit version of Windows. This installation provides full 4GB to SQL Server using WOW emulation technology.
The amount “8TB” comes with 64-bit processor architecture. This architecture offers full 8TB for applications, hence 64-bit version of SQL Server running on 64-bit Windows should use 8TB without any issue. However, this is not possible yet because of unavailability of Windows operating system that supports 8TB. The maximum amount of RAM supported by Windows 2012 is 4TB. Therefore, we need to wait for seeing SQL Server using full 8TB for user address space :).
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