Cleaning up disks from prior installs

[Will Senn <will.senn%gmail.com@localhost>]

    I'm not yet entirely clear
      on netbsd's approach to partitioning. I have my T430 set to UEFI
      only, no CSM. I have noticed that during installation, sticking to
      GPT, I have issues with the disk provisioning steps that are
      baffling. The solution I've found to be repeatable and dependable
      is to boot into linux mint's live usb, run gdisk and zap the gpt
      and mbr partitions on the disks then the install never fails.
      Since I'm trying to dedicate the laptop to netbsd, this seems less
      clean than I'd like. I took a look around and can't find any
      netbsd way of zapping the drives that's quick and dependable,
      leaving no effective trace of whatever might have been there (not
      like zeroing out the whole disk). Is there a "delete partitions
      and signatures from a drive" utility that's on the install media
      that I can run before doing a clean install?
      
      I tried dd if=/dev/zero bs=4M count=lotsofthem and the installer
      failed to create the filesystems. Maybe lotsofthem were too many
      and I should only have done some smaller number?
      
      Thanks,
      
      Will