Database Reference
In-Depth Information
If you plan to overcommit memory, make sure you have enough disk space to
create the vswap file; otherwise, the VM will not start.
Throughout this chapter, we have talked about how important it is not to overcommit
memory. In the real world, the customers that get the most out of their VMware
environment routinely overcommit resources. They only overcommit once they
understand how resources such as memory are needed and used. Coming out of the gate,
follow our guidelines and don't overcommit. Let at least a full business cycle go by.
Once you understand the resources that are needed and when they are needed, it is okay
to introduce overcommitment into your environment. It is the key to making sure your
mission-critical virtual machines have the resources they need when they need them.
SQL Server Max Server Memory
When you configure how SQL Server uses memory, you have two options available to
you:
Use Max Server Memory.
Use Min Server Memory.
These two options establish the upper and lower limits for the amount of memory used
by the buffer pool within the database. Min Server Memory controls the minimum
amount of physical memory that the database engine will try to keep committed. When
you set Min Server Memory, the buffer pool does not immediately acquire the memory
you specify. When the database starts, it only acquires the minimum amount of memory
that is needed to start the database. It grows over time, as the database needs more. If
the Windows operating system needs the memory for itself, the database may never
reach the setting you established for Min Server Memory.
Max Server Memory is the opposite of Min Server Memory. Max Server Memory
establishes the high water mark for how much memory the SQL Server database can
consume. Max Server Memory is the amount of memory in megabytes that is managed by
the SQL Server memory manager.
Both of these values can be set using sp_configure. The more important of these two
choices is to configure Max Server Memory.
Caution
When configuring the database, you have two choices: Max Server Memory and
Min Server Memory. Doing nothing is not an option. It is important that you set
Max Server Memory to prevent the database from negatively impacting the
operating system.
