To achieve backup and recovery on virtualized servers, you could save a copy of each VM and store it somewhere on the network where you can recover it if needed. In fact, many companies employ this very method, although it does present its own problems. Specifically, you can’t restore individual files without restoring the entire VM. And usually, you don’t want to recover the entire VM—just individual files that need to be reconstituted after someone inadvertently corrupted them.
Virtualization technology encapsulates everything in the VM, which is part of its allure. For example, you have the freedom to move copies of your VMs between servers that you have scattered around the network. While this mobility is useful in some circumstances, it also presents consistency complications when it comes to backup and recovery.
Fortunately, the industry is rapidly developing a variety of approaches to this problem, so you can reap the benefits of virtualization without compromising backup and disaster recovery. Here are the five basic approaches for data protection.
1. Traditional host-based agent. To implement this approach, organizations first license a backup agent and install it on each server. The backup software on their dedicated backup server initiates the backup of all servers through the agents. This method is suitable when each server is running one application, but it’s cumbersome, inefficient, and costly when dealing with virtualized servers.
2. Service console-based agent. In this method, an agent running on the VMware Service Console executes the backup. It can leverage VMware snapshots for crash consistency and back up the entire VM file (VMDK). Unfortunately, there’s no file-level restore, and it still requires processing by the ESX (VMware virtualization) server. However, in the future, VMware is investing in ESXi as their sole hypervisor. ESXi is a very light weight hypervisor, so it doesn’t maintain a console server.
3. Consolidated backup proxy agent. This approach takes advantage of the VMware Consolidate Backup (VCP) proxy, which removes processing chores from the ESX server. It improves manageability of IT resources by using a single agent running on the proxy server rather than an agent on every VM. It expedites recovery by recovering individual files, even from an image-level backup, without having to recover the entire image first. It also allows volume-level backup and recovery for VMware environments and can leverage other options, including the ability to perform incremental delta block image-level backup to expedite backup operations, save storage capacity, and enable single-pass, full VM recovery.
4. Intelligent advanced host-based agent. For this method, an agent with snapshot and deduplication capabilities works in conjunction with a data deduplication backup repository to store only unique data blocks, eliminating up to 90% of what a traditional backup agent would require.
5. Event-based data protection. This method provides replicated data protection with rollback capabilities using Continuous Data Protection (CDP) with on-demand consistency point generation, while low server overhead allows scaling to hundreds of servers. It allows both failover and failback and can replicate data across any distance.
Every organization is different, so no single backup and recovery solution fits all. Your choice depends on the level of recovery you want, how much VM performance impact you can accept, and your capacity and infrastructure requirements. For example, if you only need local image or local file recovery, any of these options will work. If you’re primarily concerned with VM performance, the VCB proxy or controller options are your best choices.