I am quite confused about the "Enable VMWare Tools Quiescence" option.
We are backing up NFS Datastores stored on NetApp appliances, these datastores contain mixed Windows and Linux guests. Now on my initial implementation of Veeam I checked the "Enable VMWare Tools Quiescence" option, because according to the documentation https://helpcenter.veeam.com/docs/backup/vsphere/tools_quiescence.html?ver=95
To create transactionally consistent backups and replicas for VMs that do not support Microsoft VSS (for example, Linux VMs), you must enable VMware Tools quiescence for the job. In this case, Veeam Backup & Replication will use the VMware Tools to freeze the file system and application data on the VM before backup or replication.
Furthermore the text under the options says "only used for machines with application aware processing disabled". Most of our virtual machines DO have AA processing enabled with pre and post scripts for both windows and linux hosts, but I have a few linux hosts with cannot be processed by AA processing for all kinds of reasons ; so I figured ok let's enable quiescence so that "machines with application aware processing disabled" are processed by it
Now the Veeam Documentation (https://helpcenter.veeam.com/docs/backup/vsphere/tools_quiescence.html?ver=95) refers to this VMware article : https://pubs.vmware.com/vsphere-55/index.jsp?topic=%2Fcom.vmware.vddk.pg.doc%2FvddkBkupVadp.9.6.html
Which clearly states that "other guest operating system" (in the context of the article other = which is not windows) are "Not applicable" and does "Crash-consistent quiescing". I think back then VMWare had an experimental feature called the sync driver for linux operating systems, but it does not seem to be the case anymore, and as far as I'm aware sync is not included in the open-vm-tools package. Yes, we use OVT and not the official tools,this is the vmware recommendation : https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2073803 :
VMware recommends using OVT redistributed by operating system vendors.
In the light of this, I don't see any upsides of enabling "VMWare Tools Quiescence" for our few non-AA linux guests, "crash consistent quiescing" does not appear very different to my than just backing it up straight away.
Furthermore, there is a lot of downsides for us for activating VMWare Tools Quiescence, from Veeam documentation :
[For storage systems working over NFS] If you enable the Enable VMware tools quiescence option in the job settings, Veeam Backup & Replication will not use Backup from Storage Snapshots to process running Microsoft Windows VMs that have VMware Tools installed.
If you enable the Enable VMware tools quiescence option in the job settings, Veeam Backup & Replication will not use the Direct NFS transport mode to process running Microsoft Windows VMs that have VMware Tools installed.
And yes, after some testing it appears that both backup from storage snapshot and directnfs are indeed not working for our windows VMs (which is counter intuitive because they have AA processing enabled)
To sum it up, my understanding of it (please correct me if I'm wrong, which was the motivation behind this post) is that in our case (just a few linux VMs without AA processing) enabling VMWare Tools Quiescence has no clear benefits and make us unable to use some veeam features (namely backup from storage snapshots and directnfs)
Sorry for the long post and thank you for your insight