> engineers conducting maintenance work mistakenly deleted critical storage connected to a key database
I'd say poor process management. Why is an engineer even deleting critical storage (I take that to mean that they are deleting something of a file-system). Perhaps they where dropping a database, but you wouldn't do it like that in a critical environment. You'd disable the database access first, and then after some time, weeks, you'd drop the database, after doing a final backup.
It could also be disconnecting a SAN, deleting a storage pool, something like that, but your process should say: Check of read activity, off-line the storage, anything non-destructive, and the only later, once you've verified that everything runs without this resource, do you delete.
At previous jobs I've worked with healthcare system. You have processes, you follow those proesses to the letter and you never delete anything as your first step. Deleting is almost always done by going into read-only mode and ageing out the data.
The fact that recovery time is four days tells me that no one followed a single procedure. Because there should be a written step by step plan, including recovery and risk assessment and when the change manager sees: "Recovery time five days" they will ask questions and stop you.
This is probably the only answer less sexy than technical debt.
