Why does ZFS have 128-bit capacity?
File systems have proven to have a much longer lifetime than most traditional pieces of software, due in part to the fact that the on-disk format is extremely difficult to change. Given the fact that UFS has lasted in its current form (mostly) for nearly 20 years, it’s not unreasonable to expect ZFS to last at least 30 years into the future. At this point, Moore’s law starts to kick in for storage, and we start to predict that we’ll be storing more than 64 bits of data in a single filesystem. For a more thorough description of this topic, and why 128 bits is enough, see Jeff’s blog entry.
