I'm a sysadmin and have run schools on bare metal and on cloud. There are things like drive failures, hardware failures, connectivity issues, networking, user access, and all of those things that are much easier in the cloud. Much easier to spin up or down if you no longer need them.
If you're running networked storage, then that needs to have both a fail-over node and backup solution. You probably need to run extra hardware, cabling, etc. Cloud trivializes this.
If you're saving 15k in terms of hard cost, but spending 55k/yr for a sysadmin on-prem to maintain, then you're not saving money at all.
A disaster can be as simple as a failed disk, or overheated server because you're not a sysadmin and you put the server in a cabinet (I've run into this, dealing with faculty). Dead computer, no lessons for the week - lost time for the school and the professor in question.
Every place is different; you have to do a cost analysis and it's not as simple as "I saved 10x!"
All the time I think I'm reading apples and then realize people were talking bananas.
It takes 5 minutes to set up a Docker Swarm Mode cluster. It takes maybe 15 minutes for k3s or microk8s. After that, auto-scaling is dead simple, and no MORE complex than some shitty vendor locked-in cloud solution.
> that needs to have both a fail-over node and backup solution
ZFS pool replication, Ceph, GlusterFS, etc. Lots of options here. These are long-solved problems.
> A disaster can be as simple as a failed disk
Right, which is why you design your on-prem cluster with N+2 redundancy in the first place, and with a locked cabinet with spare parts. Cattle not pets, and all that. Do you think your EBS storage never fails? You'd need to do exactly the same thing in the cloud, anyway.
> but spending 55k/yr for a sysadmin on-prem to maintain
First, if you're paying only 55k for sysadmins, you should be planning to fail anyway. Competence is compensated quite a bit north of there.
Second, assuming the context is small business, you're going to have role crossover anyway, it's inevitable - chances are that your developer(s) is(are) administering this. Not every business is Facebook.