Repeated allocation pattern under such condition may cause fragmentation of the memory blocks and consumption of virtual address space. When the SQL Server process has reached the state where Total Server Memory = Target Server Memory = max server memory, there are policies in SQL Server memory manager to let new allocations request multiple 8 KB pages to succeed temporarily. These values will typically increase in multiples of the "max server memory" value up to almost 8 TB.
The following data points will continue to increase over time:ĭMV: sys.dm_os_process_memory and sys.dm_os_memory_nodes - column virtual_address_space_reserved_kbĭBCC MEMORYSTATUS - Memory Manager section - VM Reserved When you're at the stage where the available virtual address space is very low, queries that try to perform memory allocation may also encounter a wait type of CMEMTHREAD. These values start off around 8 terabytes (TB) on an 圆4 process and continue to climb down and reach a few gigabytes (GB). When you examine the following information points, you will find that there is very low available virtual address space:ĭBCC MEMORYSTATUS - Process/System Counts section - Available Virtual MemoryĭMV: sys.dm_os_process_memory - column virtual_address_space_available_kb Queries take a long time to finish execution and encounter SOS_MEMORY_TOPLEVELBLOCKALLOCATOR waits. Failed allocate pages: FAIL_PAGE_ALLOCATION 513
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