In Esxi, I use the free Nakivo backup and replication, its incredibly easy to setup, has a really nice interface, and i would say it is iOS easy to use. It allows backup overwrites, daily, b-weekly, weekly, monthly, yearly - beyond that, you can choose how many copies of each you want saved, for rollbacks, etc. Has encryption for over lan backups. I am quite impressed by it. It backs up my windows server every night, 250gb takes about 1.5 hours or so. I would have to check the log to verify. backup drive is just a 4tb, located in the server. i think it supports vpn too for offsite, but i havent messed with that yet.
fair warning, I have never used it to replicate yet to test its ability to restore a server. which I really should do. ive been backing up my data independently, even if i had to rebuild, i still have everything. come to think about it, i must have tested it...been to long to remember, but i do see that i must be running my main server off the replication, lol.