What is Target Server Memory (KB)?
To super simplify in conventional memory model SQL Server calculates something like target1 and target2 pages using below formula
Target1 = Current committed pages of SQL Server + ( Available Physical Memory – min (Total Physical Memory Pages / 20, Available Physical Memory Pages / 2))
ullAvailPageFile: The maximum amount of memory the current process can commit, in bytes. This value is equal to or smaller than the system-wide available commit value. To calculate the system-wide available commit value, call GetPerformanceInfo and subtract the value of CommitTotal from the value of CommitLimit.
If (Max Server Memory < ullAvailPageFile)
{
Target2= Max Server Memory
}
Else
{
Target2=Total Physical Memory
}
Target Server Memory (KB) =Minimum (Target1,Target2)
So if AvailablePhysicalMemory is very high (or) when MaxServermemory is low then Target Server Memory (KB) would give you the MaxServerMemory else value derived from above formula.
Thanks
Karthick P.K
MSSQLWIKI 