Avamar: Tips when backing up non-VMware virtual machines hosted on Linux systems

• The Avamar client is located at a site remote from the Avamar server (5 Mbits upload speed)
• The VM images are stored on a SAN
• The VM images are each ~500 GB in size

A customer is using a Linux system as a QEMU KVM hypervisor to host virtual machines. They are not able to back up a consistent copy of the virtual machine images.
 
The virtual machines are constantly in production and cannot be powered down except after change control approval.

The virtual machines are constantly running, and the image files are constantly being written to.
With large virtual machine images, many changes to the file occur while Avamar processes it. This results in an inconsistent backup. 
UNIX and Linux clients for Avamar do not typically make native use of snapshot technologies.
 

How are large, in-use files handled in other environments?
Microsoft clients rely on VSS to provide a snapshot of the file system. This avoids inconsistencies when backing up changing files. 
 
VMware virtual machines use dedicated image proxy clients. These create snapshots of the VM disk images before they are backed up.
 
Avamar provides plugins for supported database applications. These use native database features to ensure consistent backup of the data. For example, using transaction logs.

The customer was provided with several options to allow Avamar to consistently back up large VM image files in a Linux environment.

1. Shut down the VM to ensure the VM image files do not change. Back up the image files
2. Create a snapshot of the VM using KVM and back up the snapshot rather than the in-use VM image files
3. Use the SAN to create snapshots of the LUNs which store the image files. Back up the snapshot copies
4. Install the Avamar client as a guest within the VM if the VM is running an operating system supported by Avamar. This allows for granular level backup and recovery of files from within the VM
5. Use Linux LVM snapshot technology such as that available with ext4 volumes. Direct Avamar to back up the snapshot, rather than the in-use VM image files