If you have critical applications then you most likely require a high availability cluster. This is because if you do not have the cluster then you won’t be able to ensure that the applications remain available even when there is a crash. In other words, if the server that you are using to run the applications crashes then consequently you will have to deal with unavailability of the applications. Of course, if you try to fix the server then it will take some time. In the meanwhile, if your applications continue to remain unavailable then you will have to incur losses as far as your business is concerned.
Interestingly, if you have the high availability cluster with you then you won’t have to worry about the aforesaid situations. Just to let you know, the cluster won’t be able to prevent your server from crashing. However, if it is reliable then it will certainly succeed in detecting some of the relevant faults related to hardware as well as software. Of course, timely detection will give you some time to prepare for situations where applications may be unavailable. Nevertheless, the cluster won’t only detect faults but is also likely to restart the applications. Surprisingly, the applications can be easily restarted without any administrative intervention.
Furthermore, if the cluster is good enough then it can easily take full advantage of another system for restarting the applications. Interestingly, for ensuring that your applications continue to remain available, the cluster may have to configure some things. For example, it might happen that the applications that have stopped running because of the crashed server will only run if some supporting applications continue to run as they were running before the crash. In such a situation, the cluster should do everything that is required for keeping the applications up and running. The bottom line is that without the cluster, your critical applications are unlikely to help you with your business.
Anyways, if you want that the applications should be continuously available then you’d also have to give some thought to replication. For this, you may start looking for a solution that is not only efficient as far as replication is concerned buy also ensures that your TCO gets reduced. Perhaps if you look for a solution that has the capability of replicating such data and applications that are considered to be a part of shared storage cluster then you’d be able to achieve what is desired or expected.