Is it logical to create a full replica of our webserver, just on a less powerful machine, using other hosting provider ( just because its cheaper ). The idea is to have a plan B, in case main server fails.
Personally all idea sounds messed up all the way, but maybe I am wrong?
It is always recommended to have another replica of your server. That will save you in case of disaster unless it is not critical at all to lose connectivity with your customers.
It is a good idea to have a replica whether it is the same specs or not. This at the ends depends on your business requirements and how much it is critical to have a down time.
Also, having the replica in another data center (hosting provider) is better than having both machines in the same location. This provides Geo-redundancy for your web server.
While it's perfectly logical to have a hot standby you have to consider the practicalities as well. The biggest hurdle with this idea is DNS.
For the second server to be of any value you need to be able to have the DNS record updated and effective promptly. That means you need a pretty low TTL. Unfortunately, there are an ever increasing number of systems that completely ignore the TTL, especially if it's set fairly short. In reality you'll likely have the original system up and running quicker than the change in DNS record starts to properly take effect.
You should also consider the portability of your web applications. Your new provider may not offer the same operating system / software version options. Just booking a new server and coping stuff from the old server to the new one probably won't work.
