Veeam Agent shuts down Hyper-VMs during backup process

[Alfa]

Hello everyone,

We are currently being repeatedly confronted with problems with the Veeam Agent for Windows in connection with Hyper-V virtualisation.
In a current example, our system has a data carrier of 900 GB, on which Windows and Hyper-V are installed, together with a VM with a virtual data carrier of 720 GB. This means that only 130 GB of memory is free in Windows.

The Veeam Agent has been set up so that it backs up the backups to a network drive via SMB. During the backup process, we can see in Windows Explorer how the memory becomes increasingly scarce until everything is finally full. At this point, the VM shuts down and then stands still until it is restarted manually. Strangely enough, the backup process of Veeam itself still goes through without any problems and the memory is free again after the backup process.

How can we solve this problem or have you ever experienced this yourself? As this system does not allow storage extensions, we have set up the backup via network drive, but it still starts to cache a lot of data on the system disc itself, especially due to the large virtual hard drive file, which causes it to fill up over time.
The problem is relatively critical, as the VM and therefore the production system stands still until it is restarted manually.

[Mildur]

Hello Alfa

Veeam Agent for Windows leverages VSS (Volume Shadow Copy Service). When a backup session starts, the agent requests the operating system to create a VSS snapshot. During the backup session, the agent reads all data from the hard disk, while any changes from endusers/services to the filesystem and applications are redirected to the VSS snapshot.

It could be that your server was altering (or adding) data blocks amounting to 130GB while the backup job was in progress. A machine that undergoes frequent and large data changes may require a lot of additional storage on the hard drive to accommodate the VSS snapshot.

The options available are to extend the storage capacity on your machine to store the VSS snapshots, or to schedule the backup during a time when the server is under minimal load, thereby reducing the required snapshot storage.

I strongly recommend opening a case with our customer support team to confirm my assumption. Debug logs from the agent and the operating system will help determine if the VSS snapshot was the cause of the system drive filling up.

One additional recommendation: consider using Hyper-V VM backup jobs instead of agent backups. Is there a specific reason why you are using the agent instead of a VM backup job in VBR (Veeam Backup & Replication)?

Best,
Fabian

[Alfa]

Hello Fabian,

thank you for your feedback.
We are using at the moment the Veeam Agent because its free and we did'nt know the other product "Veeam Backup & Replication" you have mentioned. Can you recommended it for Windows Server with Hyper-V? Will it work without VSS Snapshot problematic?
But on the website we cannot find the price for it. If the cost of this software were higher than the cost of the server, it would be uneconomical.

[Mildur]

Veeam Backup & Replication will have similar space requirements when it comes to VSS snapshots, so it probably won't solve your storage situation.

Veeam Backup & Replication is available as a free Community Edition for up to 10 workloads (VMs).
We recommend protecting VMs with VM backup jobs. While agents are also a viable option, they do require an agent for each machine. On the other hand, using VM backup jobs in Veeam Backup & Replication eliminates the need for separate agents to protect your Hyper-V machines.

Some additional benefits of Veeam Backup & Replication include immutable storage (limited to hardened repositories with the free version), backup copy jobs, and application item restore. The paid version offers additional capabilities, such as automated recoverability testing (SureBackup) and guaranteed support responses. If it is critical that your machine stays online and that backups work flawlessly, I recommend to consider to license our product. You can find a feature comparison between community edition and licensed editions in the following document:
https://www.veeam.com/veeam_data_platfo ... son_ds.pdf

You can request an offer by contacting our sales team:
https://www.veeam.com/contact-sales.html

Best,
Fabian