I received the following Veeam One email alert either while a backup was running or at some point after I cancelled it. The backup job was for a single Windows VM named srv-file. It has a system drive and a large D drive. The D drive is in a separate datastore.
I think the issue is snapshot related and the fact that the VM has an additional 16TB datastore attached to it.
The images below show what I have for datastores on this particular host (esxi-2):
What's confusing me is the fact that the srv-file VM's system drive is thin provisioned for 250GB but the system drive and the 16TB D drive are combined in the Provisioned Space column of the datastore (1TB SSD) which contains only the system drive.
You may try to play with alarm suppression settings to suppress the alarm during backup activities/snapshot creation or during specific hours when the job is expected to be running.
So its just a "false" alarm? Nothing to be concerned about? It's not really gonna fill up that 1TB drive when the snapshot is created even when that 16TB drive becomes more full? I was thinking that I may need to make that 16TB drive independent-persistent and use Veeam agent to back up that VM.
I would not call it a false alarm. It is correctly stating that the space provisioning on the datastore has gone above the configured alarm threshold. On the other hand, this is caused by the snapshot/backup creation process, so this is should be a temporary issue. However, if this causes concern, actions should be taken. E.g. you may move that VM to another datastore having more capacity.
All VMs are stored in the same datastore, on a small physical drive (1TB). This particular VM's system drive is stored in the same datastore plus it has that other large array/datastore attached to it. Which disk/datastore is used for the snapshot creation of this VM? Since the attached datastore (D drive) could potentially be as large as 16TB, wouldn't the snapshot be too large to fit on that 1TB drive? How does the system handle this situation? I guess what I'm asking is, does the datastore that contains the system disk have to have enough free space to accommodate a snapshot that could potentially be as large as the 16TB drive?
In vSphere VM snapshot is usually stored in the same datastore where the corresponding VM files are originally stored - this is controlled purely by vSphere itself and not by Veeam since we integrate via vSphere APIs. Before snapshot creation, the system reserves the amount of space on the datastore required to store the snapshot files. Most likely, this is when the alarm got triggered in your particular scenario.
Yes, the datastore storing VM and snapshot files should have enough free space for accommodating these files, and a backup job will throw an error if there is not enough space required for successful snapshot creation.
