Feature: Volume snapshot enhancements for VMware

Background: 

We currently use OVA as the exchange format for templates and snapshots, OVA is good for data exchange, but not for provisioning, when we deploy OVA, we actually need to unpack it into VMX and VMDK files, on the backup side, when we do a full volume backup, we first get VMX and VMDK files and then package it into OVA. When packing/unpacking logic is running inside a VM with remote storage, it means double amount of data transfer (read/write) will happen through the network. It exponentially increases the time when volume becomes rather large.

What we can improve here is to support OVF for volume backups (volume snapshots), this can eliminate the process of packing an OVA in secondary storage, it could boost the performance of volume backup and make it comparable to plain data copy.

There is another possibility that we can do but haven't tried, is to leverage storage network fully and get rid of secondary storage VM process, VMware supports datastore-copy, and datastore-copy can eliminate the data path that we have to manage through SSVM. However, the file being involved in datastore-copy are mainly flat VMDK files, which means that they are not optimized for storage,  so this approach implies more storage needs and more network bandwidth(we are talking about storage network though) . It may cancel out some of the benefits we gain from doing datastore-copy over storage network. If we can make full volume backup comparable to plain data-copy , in short term, improving full volume backup performance may partially solve the problem

Requirements:

-          Remove SSVM as a bottleneck – use direct datastore copy via vCenter/ESX host orchestration, it will bypass SSVM, however the process uses raw VMDK (not compressed) content, it has to happen at storage network

-          Remove the inefficiencies of converting from one format to another – today,template/snapshot are recorded as OVA (single file for upload/download), it is time consuming to package it in SSVM, if we can support multiple files as single template or snapshot, we can get rid of packaging process, this can speed up the process