Proudly ashamed that I just kneecapped the full-disk #LUKS encryption on one of my personal #Linux servers.
I decided that the device was in a secure-enough location, and being able to auto-start on boot (e.g. after a power outage) was more important than protecting the drive contents.
This is the technique I used, which has the benefit that I can relatively easily reverse the change later on: https://web.archive.org/web/20140930221049/http://atterer.org/linux-remove-disable-luks-encryption-password-on-disk-partition-crypttab-initrd