Goal

The cluster will lose fencing, when a user runs e.g. `pcs stonith sbd disable` and no other fencing mechanism is configured. The user should be warned about this.

Please, check if fencing will be lost after actions that can lead to it. Send forceable error if such situation can happen.

This issue can be complex (it is necessary to check sbd and also fence device commands). So, this problem could be solved by planning and creating separate JIRAs for each subtask.

Acceptance criteria

• pcs exits with an error and doesn't change cluster configuration in these scenarios:
  • user disables sbd (using 'pcs stonith sbd disable' command) and there are no effective stonith resources in the cluster
  • user disables the last effective stonith resource in the cluster (using 'pcs stonith disable' command) and sbd is disabled
  • user removes the last effective stonith resource in the cluster (using 'pcs stonith delete | remove' command) and sbd is disabled
• web ui reports an error and doesn't change cluster configuration in the same scenarios:
  • user disables sbd (using 'Disable SBD' button) and there are no effective stonith resources in the cluster
  • user removes the last effective stonith resource in the cluster (using 'delete' button in the stonith resource page) and sbd is disabled
  • disabling stonith resources is not supported in web ui, therefore this scenario doesn't apply
• the error can be overridden
• effective stonith resource is a stonith resource which
  • is not disabled
  • is capable of fencing (for example, fence_kdump is not capable of fencing)