As I am sure most of you are aware, VMware Virtual SAN (VSAN) is now generally available with vSphere 5.5 U1. Perhaps you have been using VSAN since its beta debut last year or maybe you are just getting started. Either way, the next logical question once VSAN has been deployed is how do I back up the VMs running on VSAN? To address that question, VMware has also released vSphere Data Protection (VDP) Advanced 5.5.6. One of the main features added to this VDP Advanced release is full support for backing up and restoring VMs running in a VSAN cluster.
It is certainly possible to deploy a VDP Advanced appliance to a VSAN cluster and back up VMs running on VSAN. However, this breaks the cardinal rule of not having your production data and backup data on the same storage. How can we address that? Keep reading…
First, I will point out that it is not necessarily a bad thing to have production data and backup data living in harmony together on the same storage platform (VSAN, in this case) as long as you have a another copy of this backup data located elsewhere. VSAN is quite resilient to issues such as the failure of a drive or a vSphere host, but that will not help when someone accidentally hits the Delete button. Having your backup data locally available enables rapid restores for situations such as data corruption inside of a VM or that inadvertent deletion of a VM.
VDP Advanced can also protect against more significant failures such as the loss of an entire storage platform or even a complete site failure. The first way this can be addressed is by using the backup data replication feature that is built into VDP Advanced. It is possible to back up data locally and then replicate this backup data to another VDP Advanced appliance.
It is also possible to replicate backup data from VDP Advanced to an EMC Avamar grid. Avamar could be located in the customer’s data center or hosted at a service provider as part of a data-protection-as-a-service offering.
Another option is to utilize EMC Data Domain as a backup data target for VDP Advanced. Data Domain Boost (DDBoost) is built into VDP Advanced and, assuming DDBoost is licensed on the Data Domain appliance, this enables a very efficient and reliable means to store backup data separate from production data. Data Domain deduplication and compression is outstanding. Below is a screen shot showing pre- and post-compression numbers for two VDP Advanced appliances I have in my environment. Note that over 2TB of raw backup data has been ingested by the two VDP Advanced appliances. After compression, only 127GB of capacity on the Data Domain appliances is consumed!
Better yet, what if we employ both approaches? It is certainly supported and looks something like the diagram below. The virtual appliances are VDP Advanced appliances and the black boxes are EMC Data Domain (physical) appliances.
As you can see there are a few ways to design a backup solution using VDP Advanced and Data Domain for VSAN (and other storage solutions, for that matter). Using Data Domain to store VDP Advanced backup data makes sense for a few reasons:
Backup data is separate from production data
Deduplication and compression dramatically reduce the storage capacity consumed by backup data
Data Domain provides a very reliable platform for housing backup data
VDP Advanced works seamlessly with Data Domain using DDBoost
Data Domain enables scale beyond the 8TB limit imposed by a VDP Advanced appliance
It is even possible to use more than one VDP Advanced virtual appliance with a single Data Domain appliance. If this is something you are thinking about doing, here are some guidelines to keep in mind:
VDP Advanced is still limited to a maximum of 400 VMs per VDP Advanced appliance
Using a Data Domain 160 or 620 appliance, one VDP Advanced is ideal
One or two VDP Advanced appliances is recommended with Data Domain 2500 and 4000-series appliances
A higher-end Data Domain 7200 appliance is best with up to three VDP Advanced appliances
Generally speaking, the “sweet spot” as far as number of VMs protected by VDP Advanced is anywhere from 50 VMs up to 800 VMs. Scaling to 800 VMs with VDP Advanced would likely be accomplished by deploying three or four VDP Advanced appliances with 8TB of capacity and/or use of Data Domain as a target for backup data. Again, these numbers are general estimates. There are several factors that determine actual results such as the amount of data being backed up (VM sizes), data change rates, the types of data being backed up, and the retention policy assigned to the backup data. Everyone’s environments are different – results will vary.
