Azure SQL Managed Instance very slow to create new databases

Question

I have two Azure SQL Managed Instances in East US. Neither of them are very loaded at the moment.

Instance1 = General Purpose - Standard Series (Gen5) 4 core

Instance2 = General Purpose - Standard Series (Gen5) 8 core

Creating a new database (simple create database statement) takes 20 seconds in Instance1 and takes 70+ seconds in Instance2.

What is causing Instance2 to take so long to create a database? Instance1 is actually more loaded (more activity and more database) than Instance2 at the moment. What should I be looking for? How can I investigate this?

Backup/retention policies are the same for both instances.

My application has been timing out trying to create databases on instance2. We keep increasing the timeout time, but this big discrepancy has me worried that something is wrong with instance2.

Answer 1

Dear Nic,

The Azure SQL MI is deployed in which mode regarding networking? VNet-local endpoint, Public endpoint or Private endpoint?

Each one of these options uses different connection type:

• Public endpoint uses Proxy
• Private endpoint users Proxy
• VNet-local endpoint uses proxy and redirect connection.

Proxy and Redirect: Proxy is the default while Redirect is the recommended one.

https://learn.microsoft.com/en-us/azure/azure-sql/managed-instance/connection-types-overview?view=azuresql#connection-types

The above settings are probably related to the timeout.

Also, all other settings like Defender for Cloud or encryption are the same?

I would also had a look into this: https://learn.microsoft.com/en-us/azure/azure-sql/managed-instance/tempdb-configure?view=azuresql&tabs=ssms

I am not a DBA but it might help.

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