For VPS mirroring, 2 vps's with same configuration are been used where data transfer keeps going on from first vps to second one after every specific time duration so if 1st vps fails because of any reason, the another one gets activated.
This is pretty much beneficial for the people who are looking for 100% uptime.
That's very true. However, to give any suggestions on such setup, it is required to know the site architecture in details to take into the consideration all data storage mechanisms it will require to be synced. For simple case it will be enough to have rsync running between two serves and some sort of script switching DNS from one VPS IP to another when the first one machine fails.
