Hi @DinoSA, welcome to the community.

AFAIK is the communication between the installed SQL plugin not in connection with a separate proxy, the agent itself will manage the required steps.

The VBR will orchestrate the configured/scheduled Job or task.

Cheers, Markus

So, just to be clear. When using SQL plugin, we cannot leverage power of Veeam Proxy. Correct ?

i would say yes, you are right. 

You can take a look at How Veeam Plug-in for Microsoft SQL Server Works - Veeam Plug-ins for Enterprise Applications to see how the plugin works. 

On the other hand, is the plugin for you really necessary - maybe you have your SQL DB running on a VM and could leverage Application Aware Processing? 

Or is the request to use the Plugin from a Database Adminstrator point of view? If you are running a SQL Failover Cluster you would be running with the plugin.
 

Hi @DinoSA -

Have you taken a look at Veeam’s Enterprise Application Plugin User Guide? The SQL Plugin section has a good diagram of how the Plugin works, and what components are used. Some highlights from the link below:
https://helpcenter.veeam.com/docs/backup/plugins/overview_mssql_plugin.html?ver=120
“Integrating Microsoft SQL Server and Veeam Backup & Replication enables Veeam Plug-in to use native Microsoft SQL Server backup features while using Veeam Backup & Replication backup management and storage capabilities.”

#3 in the link below:
https://helpcenter.veeam.com/docs/backup/plugins/hiw_mssql_plugin.html?ver=120
“The MSSQLRecoveryManager service starts the source Veeam Data Mover on the Microsoft SQL Server machine, and Veeam Backup Manager in Veeam Backup & Replication starts the target Veeam Data Mover on the Veeam backup repository.”

And one of the diagrams:

Basically, Veeam uses a ‘Data Mover Service’ installed on the SQL Server where DBs are you want to backup, as well as a Data Mover on the Veeam Repository. No Proxy is used.

Hope that helps a bit

Additional question regarding plugin-based backup 
When backup is created, the BAK file is stored locally on SQL server until written on backup repositories.?  

@DinoSA -

According to the Plug-in Guide, Veeam stores backups in a Veeam Repository you configure. See Guide for more info on this:

https://helpcenter.veeam.com/docs/backup/plugins/data_backup_mssql_plugin.html?ver=120

https://helpcenter.veeam.com/docs/backup/plugins/repos_mssql.html?ver=120

Best.

Thank you for your answer.
I might send the wrong question. During the backup of Database via SQL veeam plugin, the creation of VDI (Virtual Device Interface) is utilized, to create store backup. My question is where this VDI is stored. is it short-term in RAM, or local disk or it's presented to SQL as Backup repositories.? 

This question is raised by client, as they want to know if creation of db will fill out their local filesystem.

Honestly, not sure @DinoSA . You could try a question with Support, or maybe a Product Mgr at the Forums would know for sure.