Deployment Considerations for Red Hat Enterprise Virtualization

Tiers Based on Service Level Agreements (SLAs)

Different virtual machines (VMs) can have different backup and recovery options that are defined in a service level agreement (SLA) for each class of VM. For example:

  • High transaction VMs that provide customer application support might require multiple daily backups with the requirement to recover virtual machines quickly.
  • User VMs might need the ability to recover specific files and folders on a daily basis.
  • Development and test VMs might only need weekly backups or the ability to recover to predefined states.

To manage different SLAs, you can create a separate subclient for each class of VM. Each subclient can have its own storage policy, backup schedule, and recovery options. 

Data Recovery Considerations

The frequency of backups should be based on your requirements for data recovery. For example:

  • To determine backup frequency, determine how long the maximum window for potential loss can be. For example, if your policy calls for no more than an hour's work to be lost in the event of a virtual machine failure, hourly backups are required.
  • If immediate recovery is a priority, you can restore a copy of a virtual machine that is frequently updated based on incremental backups.

Sizing, Performance, and Load Balancing

There are no explicit limits on the size of backups, number of virtual machines, or size of virtual machines that can be backed up; but you must ensure sufficient storage. You can configure a subclient to check for sufficient free space in the storage domain before performing a backup.

The following factors can affect backup performance:

  • Size and type of backup: More data means longer backups. The size and number of virtual machine disks affects backup time, and full VM backups take longer than incremental backups.  Best practice is to monitor backup operations against operational windows to ensure that virtual machines are backed up within expected times.
  • Network speed and traffic: Backups are faster on high-speed networks and during times when network traffic is low.
  • Application activity: To lessen the impact of backup operations on applications running on VMs on the same Red Hat cluster, perform backups when host usage is lower.
  • Number of Virtual Server Agent proxies: Add multiple proxies to a Red Hat cluster to back up multiple VMs in parallel; but limit the number of additional proxies to reduce the performance impact on the host.  
  • Number of backup streams: You can define multiple streams to run backups and restores in parallel and improve the data transfer rate; but only one data read stream is supported for each disk. For more information, see Streams - Overview.


Create backup schedules for subclients to ensure that backups are performed at regular intervals. To balance full VM protection against the need for more frequent backups, you can schedule regular full backups and more frequent incremental backups. You can recover full VMs from full or incremental backups.

When possible, schedule backups for different subclients at different times to avoid competition for resources, and schedule large backup operations during times when the network is less congested.

Last modified: 1/18/2019 7:38:57 PM