VMware introduced vStorage APIs for Data Protection (VADP) so that backup products can do centralized, efficient, off-host LAN free backup of vSphere virtual machines.
In the physical world, most systems have plenty of resources, often underutilized. Running backup agent in such a system wasn’t a primary concern for most workloads. The era of virtualization changed things drastically. Server consolidation via virtualization allowed organizations to get the most out of their hardware investment. That means backup agents do not have the luxury to simply take up resources from production workloads anymore as the underlying ESXi infrastructure is optimized and right-sized to get line of business applications running smoothly.
VMware solved the backup agent problem from the early days of ESX/ESXi hosts. The SAN transport method for virtual machine backup was born during the old VCB (VMware Consolidated Backup) days and further enhanced in VADP (vStorage APIs for Data Protection). The idea is simple. Let the snapshots of virtual machine be presented to a workhorse backup host and allow that system do the heavy lifting of processing and moving data to backup storage. The CPU, memory and I/O resources on ESX/ESXi hosts are not used during backups. Thus the production virtual machines are not starved for hypervisor resources during backups.
For non-SAN environments like NFS based datastores, the same dedicated host can use Network Block Device (NBD) transport to stream data through management network. Although it is not as efficient as SAN transport, it still offloaded most of the backup processing to the dedicated physical host.
Dedicating one or more workhorse backup systems to do backups was not practical for small business environments and remote offices. To accommodate that business need, VMware allowed virtual machines to act as backup proxy hosts for smaller deployments. This is how hotadd transport was introduced.
Thus your backup strategy is to use a dedicated physical workhorse backup system to offload all or part of backup processing using SAN or NBD transports. For really small environments, a virtual machine with NBD or hotadd transport would suffice.
Somehow EMC missed this memo. Ironically, EMC had been the proponent of running Avamar agent inside the guest instead of adopting VMware’s VADP. The argument was that the source side deduplication at Avamar agent minimizes the amount of data to be moved across the wire. While that is indeed true, EMC conveniently forgot to mention that CPU intensive deduplication within the backup agent would indeed leech ESXi resources away from production workloads!
Then EMC conceded and announced VADP support. But the saga continues. What EMC had provided is hotadd support for VADP. That means you allocate multiple proxy virtual machines even in the case of enterprise vSphere environments. Some of the best practice documents for Avamar suggest deploying a backup proxy host for every 20 virtual machines. Typical vSphere environment in an enterprise would have 1000 to 3000 virtual machines. That translates to 50 to 150 proxy hosts! These systems are literally the leach worms in vSphere environment draining resources that belong to production applications.
The giant tower of energy consuming nodes in Avamar grid is not even lifting a finger in processing backups! It is merely a storage system. The real workhorses are ESXi hosts giving in CPU, memory and I/O resources to Avamar proxy hosts to generate and deduplicate backup stream.
The story does not change even if you replace Avamar Datastore with a Data Domain device. In that case, the DD Boost agent running on Avamar proxy hosts are draining resources from ESXi to reduce data at source and send deduplicated data to Data Domain system.
EMC BRS should seriously look at the way Avamar proxy hosts with or without DD Boost are leaching resources from precious production workloads. The method used by Avamar is recommended only for SMB and remote office environments. Take the hint from VMware engineering as to why Avamar technology was borrowed to provide a solution for SMB customers in VMware Data Protection (VDP) product. You can’t chop a tree with a penknife!
The best example for effectively using VADP for enterprise vSphere is NetBackup 5220. EMC BRS could learn a lesson or two from how Symantec integrates with VMware in a much better way. This appliance is a complete backup system with intelligent deduplication and VADP support built right in for VMware backups. This appliance does the heavy lifting so that production workloads are unaffected by backups.
How about recovery? For thick provisioned disks SAN transport is indeed the fastest. For thin provisioned disks, NBD performs much better. The good news on Symantec NetBackup 5220 is that the user could control the transport method for restores as well. You might have done the backup using SAN transport, however you can do the restore using NBD if you are restoring thin provisioned virtual machines. For Avamar, hot-add is the end-all for all approaches. NBD on a virtual proxy isn’t useful, hence using that is a moot point when the product offers just virtual machine proxy for VADP.
The question is…
Dear EMC Avamar, when will you offer an enterprise grade VADP based backup for your customers? They deserve enterprise grade protection for the investment they had done for large Avamar Datastores and Data Domain devices.