I don't know what is the reason to vote-down this question, can you all help me find out this possible vote-down reason?
It's hard to tell how many servers you're talking about and how they're used:
- how many is "lots" of backup servers
- what do you mean by "slower unstable-online" ?
- what does "unlikely unavailable" mean? Did you mean likely?
I just read the question, and I don't understand what you are looking for.
I was about to think that you mean backup server, to create a backup, but as I seen the tag haproxy so I guess it's for that product.
For me it's unclear as-is. Please edit to add detail.