I'm afraid that snapshots are not, by any means, a way to backup your VMs.
One good metaphor is to imagine a clerk piling up papers in a side of this desk. He knows he will be asked by his supervisor to report the work done during the week, so he just inserts a posit note before leaving the office each day and continues to pile up papers when he arrives the following day. If at any time, he is asked to report how much work he had finished by, let's say, Wednesday, he just has to remove the papers on top of the Wednesday posit and the state of the pile will be returned to exactly the time when he left the office on Wednesday evening. Once the supervising labor has ended, he can remove the posit separators and there will be no way to know the state of the pile at a given day, but all information will be there anyway.
The information contained between the posit notes are the snapshots, we can remove posit notes and consolidate the papers with the data underneath, or remove the topmost block of papers and revert the state of things to how they were the day before. But that does not mean we have a copy of the paperwork.
If for whatever reason: I/O error, hardware flaw or physical damage arise and one of the snapshots or base disks gets damaged, you may loose your VM, and won't be able to restore it.
We offer a totally free VMWare ESXi backup solution that is cron programmable and allows to perform hot backups of your VMs. There is no limit in the number of VMs you can backup and you can install to any number of hosts. It has an extremely low footprint on your servers and it is a stand alone solution that works in the free version of ESXi, so you can use it to backup your VMs in spare servers, like in a hosting environment.
Download here: https://33hops.com/xsibackup-vmware-esxi-backup.html
Man page: https://33hops.com/xsibackup-help-man-page.html