Sorry , I'd like to clarify my question:
1/ You mean we still should enable Veeam Guest Proccessing even if the VM is File Server or there's no any VSS-application like Exchange, Sharepoint, MSSQL, AD? That's mean we need an GUEST OS account to enable it from Veeam?
Veeam do Application Aware Backup and treat the windows system in a way that is defined by Microsoft for backup.
For example there are everal system services that have VSS Writer and want to be brought in a consisten state before backup.
As well the filesystem should write the RAM cache down to the disks. Otherwise you could end up with damaged files on windows if not all writes went down to disk.
We set as well some things that allow a customer/windows to detect that a server was restored , which is important in several support cases.
2/ What happen if we enable VMware Tools Quiescense and freeze disk at VMware Tools for these Windows VM? I read from the artical that we have Windows and VMware VSS-supported applications (without known user for Guest OS processing)? What is that?
If you disable Veeam Guest processing, you have the option to eanble VMware Tools Quiescense. This perform basic VSS processing.
Think about it that way:
VMware Tools Quiescense => Tell the system that it will be copied.
Veeam Guest processing => tell the system that it get´s backed up.
Both work in case of consistency and would be fine for your file server.
3/ For these Windows (File Server), is it possible if we backup it in crash consistent mode?
I would not do this... Many customer do it that way without issues, but NTFS and REFS filesystems where not designed to be backed up in a crash consistent state.
According to https://helpcenter.veeam.com/docs/backu
... tml?ver=95, the VSS is already enable in VMware tools and no required steps to enable it again?
Corrct. You only need to enable it on the Veeam Job side under Storage-Advanced-VMware (this is only used if Veeam Guest processing is disabled)