[kelnos]

Battery backups, of course.

There will always be failure modes. I mean, the failure mode for a traditional lock is "I lost my keys". Unless you have someone else with a spare set who can get to your location in a time you deem reasonable, you're going to have to have the door forced.

[WalterBright]

I once had a storage unit, and lost the key to the padlock. The manager said "no problem", and we went out to the unit. The manager pulled out a battery operated angle grinder, and cut the lock off in about 5 seconds.

You're going to need a bank vault to beat an angle grinder. Those tools are the shiznit.

[acuozzo]

> You're going to need a bank vault to beat an angle grinder.

To beat? Agreed.

With that being said, grinding through a circular padlock takes much, much longer. I'd suggest using one of those for a storage unit.