On while some are off

We trust blockchain because it guarantees that all nodes are updated about the status of blocks. Distribution of updated status of blocks among all nodes makes fraud impossible.

But, is it really true that all nodes always are updated? The honest answer is no.

Some nodes may be off in some times or some may be out of order for a long time. The fault tolerant mechanism of blockchain enables the system operates and consensus reaches while all nodes are not necessarily working. In fact, when a network come back to the system, it needs to be synced and updated regarding the data to operate again, while system is working.

However, what if as a validator in PoS system we want to be always updated without a failure. We have to have a back up to be able to work 24/7/365. This raise technically a problem in blockchains.

What if as an individual wants to rely on a validator that that runs continuously. We have to split our stake into different validators.

However, Fault Tolerant Staking offer a solution for the problems mentioned above.

Fault tolerant staking is a clustering of nodes to shape a validator. If a node in a cluster (validator) fails to work then the other can step in.

This ensure the system that nodes are always on and ensure the individuals (delegators) that their delegated validators are always on.