More comprehensive disk cleansing
As we (mostly Powder) pick up more industrial (non-acedemic) users, zeroing of disks between experiments will probably become more important. We have a path for doing this, and @kwebb uses this in his "tainting" of experiment nodes (originally for PhantomNet), but it is an expensive operation right now because it requires frisbee write zeros to all free blocks.
There are other thiings we can do:
- Use the "block erase" support that many (most? all?) SSDs and NVMe devices support. We use this currently in conjunction with our TRIM support and, at least for devices we have, requires less than a minute to erase up to 500GB devices. Presumably this is because it only marks all the blocks for erasure and does the work in the background.
- Make use of SEDs (self-encrypting disks). We have talked about this since NCR days, but if you just change the encryption key for disks between experiments, you have effectively erased the old content. I think we have some of these disks, and there is FreeBSD/Linux support for manipulating these.
Another consideration is whether we erase all disks between experiments. That could be really, really painful on those Clemson nodes with 40+ HDs...