Let's say Alice owns a server that stores highly sensitive data. Let's further assume the data is worth a lot, but losing all data is way less of a problem than having it read by attacker Mallet.
To have the data safe in normal operation, all the harddisks have LVM and LUKS with full volume encryption enabled. There is one keyslot enabled. The server is protected against power loss via UPS.
Alice could see Mallet, physically trying to steal the harddisks, coming, ssh into the server and issue
cryptsetup luksErase to permanently destroy the header and thus make the data unrecoverable.
If, however, Mallet sneaked into the server room, unplugged the server from the UPS without shutting it down, and then took out the drives, the LUKS headers with the keys would still be on there. Assuming Mallet had the computation power at his hands to break the password, he could unlock the volumes.
Now I came up with this: What if the server, once the volumes are unlocked, overwrote the headers? In a case of sudden power loss, all data would be gone forever. When Alice needs to reboot, she could copy the data off the unlocked volume to another disk, reboot, reinitialize the LUKS volume and restore the data, then destroy the external disk.
Would that be safer or is it sufficient to choose a long enough password for LUKS? (Not to mention the solution is surely paranoid, but just in theory)