Some time ago, when I tested the MEMORY database of SQL Server 2014, I found that if the size of the database exceeded the set maximum memory, Error: 701 occurred in SQL Server.
 
Error message:
 
Error: 701, Severity: 17, State: 123.
There is insufficient system memory in resource pool ‘internal’ to runthis query.
 
At that time, I deleted the database and restarted it. In fact, I could still connect it with DAC when I was out of memory.
 
Here’s what I did:
Default connection failure:

The DAC connection is successful (you can also use SQLCMD DAC):

 
Since the server still had memory resources at that time, It was ok to directly modify the maximum memory:
 
sp_configure ‘show advanced options’, 1;
GO
RECONFIGURE;
GO
sp_configure ‘max server memory’, 4096;
GO
RECONFIGURE;
GO
 
If connected to THE DAC, you can check the status of the system, and the session found some problems can be processed, so there is no need to restart the SQL Server, and problems can be found in a timely manner.