You clearly don't understand how quiescence is supposed to work and seem to think it's only a VMware or hypervisor phenemon. It isn't. It's been around for literally years even before virtualization began.
Well, tell me then.
You need to read about VSS basic concepts. Quiescence is useless unless there are writers, and this is exactly what database vendors provide. The command to quiesce doesn't just flush files to disk, it informs these applications that provide a writer that a backup is about to happen. The application then handles the logic to write out any outstanding in-memory I/Os to disk. This writer and requestor structure is the whole reason why quiescence does provide application consistency and not crash consistency.
I tell once more - VSS is windows technology and I dont have windows there in VM. And even when I have windows, VSS cant do nothing with 3rd party servers or databases.
No, database vendors dont provide VSS compatibility. Writers for VSS can made only for windows system. Not for Linux, not for BSD, not for UNIX, only for windows. Secondly, there is no "database vendor" for server software. Usually servers and 3rd party software use their own made unstandard databases. They even dont call them databases, its just software logic, but actually its still database. Thats because they dont have database agents, because its not actually database. The only suggest server brand can give, is to shut server down and make backup. Of course its unacceptable. But I dont need this writer for quiescene. I can just make VM snapshot with memory. Then make storage SAN snapshot for that LUN. Then make storage SAN snapshot replication to another SAN or to different storage pool in the same SAN. This is very fast operation, integrated into storage hardware, uses CBT (changed block tracking). Then I can delete storage SAN snapshot of LUN. Then I can delete vmware VM snapshot. Also, hardware storage SAN have also automation for all this. It have sheduling and also vmware compatible snapshot agent. And I dont need any writer at all.
So, again, that isn't the fault of the principle of quiescence, that's the fault of whoever this vendor is. If they don't recommend anything then either A.) they don't need their application/system quiesced and crash-consistency is good enough or B.) they're a crap company and don't care about supporting their users in operation. Either one you pick, this doesn't negate the usefulness or operation of quiescence.
Yes it is. You dont need to do quiescene through guest writer. You dont need to stop databases, dont need to prepare databases for backup. Its all useless and not possible in most cases. You can instead backup whole VM together as it is in real time, nothing changing, together with memory. And when you restore, you can get server working and online exactly in the same point. Just first revert SAN snapshot, then revert vmware VM snapshot and your server is in the same time moment.
I don't even know what you're talking about here. The brand of physical server makes no difference, it's the operating system and application which determine how data protection must be managed. You don't ask HPE how to take application-consistent backups of Oracle running on a DL380, you ask Oracle how to do that. The physical platform makes no difference.
I recommend you spend some time on Google reading about how quiescence really works and stop making wildly false claims based on incorrect understanding of these principles.
So, you dont know what is embedded VM? In OVF or OVA format? They are not physical, they are virtual. And yes, any influence to its operating system is prohibited. If you talk to support that you insert something into operating system, then support first request you to delete whole VM and install pure plain one. Because this kind of action is not supported and allowed. Its hacking and against of license. There is no Oracle, most server databases are unique, only made for this software, there is no standard. Only external databases are standards.