Symantec’s NetBackup has been in the business of protecting the VMware virtual infrastructures for a while. What we’ve seen over the last couple of versions is the maturing of a product that at this point works very well and offers several methods to back up the infrastructure.
Of course, the Query Builder is the mechanism that is used to create and define what is backed up. The choices can be as simple as servers in this folder, on this host or cluster—or more complex, defined by the business data retention needs.
Below are the high level backup methods with my thoughts around each and merits thereof.
1: SAN Transport
To start, the VMware backup host must be a physical host in order to use the SAN transport. All LUNS (FC or iSCSI) that are used as datastores by the ESX clusters must also be masked and zoned (FC) to the VMware backup host.
When the backup process starts, the backup host can read the .vmdk file directly from the datastores using vADP
The obvious advantage here is one can take advantage of the SAN fabric thus bypassing all resources from the ESX hosts to backup the virtual environments. Backup throughput from what I’ve experienced is typically greater than backups via Etnernet.
A Second Look
One concern I typically hear from customers specifically with the VMware team is that of presenting the same LUNS that are presented to the ESX cluster to the VMware backup host. There are a few ways to protect the data on these LUNS if this becomes a big concern, but I’ve never experienced any issues with a rogue NBU Admin in all the years I’ve been using this.
2: Hot-add Transport
Unlike the SAN Transport a dedicated VMware backup host is not needed to backup the virtual infrastructure. For customers using filers such as NetApp or Isilon and NFS, Host-add is for you.
Just like the SAN Transport, this offers protection by backing up the .vmdk’s directly from the datastores. Unlike the SAN Transport, the backup host (media server) can be virtualized saving additional cost on hardware.
A Second Look
While the above does offer some advantages over SAN Transport, the minor drawback is ESX host resources are utilized in this method. There are numerous factors to determine how much if any the impact will be on your ESX farm.
3: NBD Transport
The backup method used with NBD is IP based. When the backup host starts a backup process a NFC session is started between the backup host and ESX host. Like Hot-add Transport, the backup host may be virtual.
The benefit of this option is it is the easiest to configure and simplistic in concept compared to the other options.
A Second Look
As with everything in life, something easy always has drawbacks. Some of the drawbacks are cost of resources to the ESX host. Resources are definitely used and noticeable the more hosts that are backed up.
With regard to NFC (Network File Copy), there is one NFC session per virtual server backup. If you were backing up 10 virtual servers off of one host, there would be 10 NFC sessions made to the ESX host VMkernel port (management port). While this won’t affect the virtual machine network, if your management network is 1GB, that will be the bottleneck for backups of the virtual infrastructure. Plus VMware limits the number if NFC sessions based upon the hosts transfer buffers, that being 32MB.
Wrap-up: Your Choice
While there are 3 options for backing up a virtual infrastructure, once you choose one, you are not limited to sticking with it. To get backups going, one could choose NBD Transport and eventually change to SAN Transport … that’s the power of change.
Photo credit: imuttoo