sys.dm_os_sys_memory (Transact-SQL)
Applies to: 
SQL Server
Azure SQL Managed Instance
Azure Synapse Analytics
Analytics Platform System (PDW)
Returns memory information from the operating system.
SQL Server is bounded by, and responds to, external memory conditions at the operating system level and the physical limits of the underlying hardware. Determining the overall system state is an important part of evaluating SQL Server memory usage.
Note
To call this from Azure Synapse Analytics or Analytics Platform System (PDW), use the name sys.dm_pdw_nodes_os_sys_memory. This syntax is not supported by serverless SQL pool in Azure Synapse Analytics.
| Column name | Data type | Description |
|---|---|---|
| total_physical_memory_kb | bigint | Total size of physical memory available to the operating system, in kilobytes (KB). |
| available_physical_memory_kb | bigint | Size of physical memory available, in KB. |
| total_page_file_kb | bigint | Size of the commit limit reported by the operating system in KB |
| available_page_file_kb | bigint | Total amount of page file that is not being used, in KB. |
| system_cache_kb | bigint | Total amount of system cache memory, in KB. |
| kernel_paged_pool_kb | bigint | Total amount of the paged kernel pool, in KB. |
| kernel_nonpaged_pool_kb | bigint | Total amount of the nonpaged kernel pool, in KB. |
| system_high_memory_signal_state | bit | State of the system high memory resource notification. A value of 1 indicates the high memory signal has been set by Windows. For more information, see CreateMemoryResourceNotification in the MSDN library. |
| system_low_memory_signal_state | bit | State of the system low memory resource notification. A value of 1 indicates the low memory signal has been set by Windows. For more information, see CreateMemoryResourceNotification in the MSDN library. |
| system_memory_state_desc | nvarchar(256) | Description of the memory state. See the table below. |
| pdw_node_id | int | Applies to: Azure Synapse Analytics, Analytics Platform System (PDW) The identifier for the node that this distribution is on. |
| Condition | Value |
|---|---|
| system_high_memory_signal_state = 1 and system_low_memory_signal_state = 0 |
Available physical memory is high |
| system_high_memory_signal_state = 0 and system_low_memory_signal_state = 1 |
Available physical memory is low |
| system_high_memory_signal_state = 0 and system_low_memory_signal_state = 0 |
Physical memory usage is steady |
| system_high_memory_signal_state = 1 and system_low_memory_signal_state = 1 |
Physical memory state is transitioning The high and low signal should never be on at the same time. However, rapid changes at the operating system level can cause both values to appear to be on to a user mode application. The appearance of both signals being on will be interpreted as a transition state. |
Permissions
Requires VIEW SERVER STATE permission on the server.
Permissions for SQL Server 2022 and later
Requires VIEW SERVER PERFORMANCE STATE permission on the server.
See also
Dynamic Management Views and Functions (Transact-SQL)
SQL Server Operating System Related Dynamic Management Views (Transact-SQL)