Backups

The Virtual Server Agent (VSA) proxy on a Red Hat cluster can perform backups for all virtual machines (VMs) running on shared storage. Best practice is to deploy at least one proxy in each Red Hat cluster. For clusters with high backup requirements, multiple proxies can be deployed.

You can perform full, incremental, or synthetic full backups of virtual machines. The first backup of a virtual machine is always a full backup, regardless of the backup type you select.

Virtual machine backup jobs are allocated to VSA proxies according to the following priorities:

1. Each VSA proxy manages backups for virtual machines hosted on the same Red Hat data center.

2. When multiple VSA proxies are available for a cluster, the round-robin method is used to choose the least loaded proxy.

3. If none of the other criteria can be used to allocate jobs for a VM, jobs are allocated by default to the coordinator node. If the coordinator node cannot access the cluster for the VM disks, the job fails.

When a virtual machine is discovered during backup, a client for the VM is created in the CommCell Console if one does not already exist. If a virtual machine with spaces or special characters in its name is discovered during backup, the spaces or special characters are replaced with underscores ('_') when creating the VM client name that is displayed in the CommCell Console. The VM name with spaces or special characters is still displayed on the Virtual Machine Status tab for the backup job, in the backup job summary, and in reports that include the VM name. The following special characters are replaced:

[ \ \ | ` ~ ! @ # $ % ^ & * + = < > ? , { } ( ) : ; ' \ " \ \ s / ]

What Gets Backed Up

The following data is backed up by the Virtual Server Agent:

• Virtual machines (powered on or powered off)

• Configuration files for each virtual machine

• Associated VirtIO and VirtIO-SCSI virtual machine disks

  When a virtual machine disk for a Red Hat virtual machine is backed up, the entire disk is read for allocated blocks, for both full and incremental backups.

What Does Not Get Backed Up

The following data is not backed up by the Virtual Server Agent:

• Proxy virtual machines on which the Virtual Server Agent is installed

• Direct LUN or pass-through disks

• Disks configured through the iSCSI initiator on guest VMs

• IDE disks

• Shared disks

Backup Types

You can perform the following types of backups, either immediately or on a schedule.

• Full backups: Back up the entire virtual machine. This is the most comprehensive backup.

• Incremental backups: Back up virtual machine data that has changed since the most recent backup.

• Synthetic Full backups: Consolidate virtual machine data from the most recent full backup with subsequent incremental backups.

• To display the Differential backup option, add the bEnableVSADifferentialBackup additional setting to the CommServe system as shown in the following table.

  For instructions on adding additional settings from the CommCell Console, see Adding or Modifying an Additional Setting.

  Property	Value
  Name	bEnableVSADifferentialBackup
  Category	CommServDB.Console
  Type	Boolean
  Value	true