I have never encountered a disk failure in my whole life but I had a dozen of bit rot and silent corruptions. 'Normal' file systems and hardware RAID can do absolutely nothing about it. I have been using application-level parity redundancy to protect my most important data, but it's apparently not quite effective.
I know ZFS store checksum of the chunks in software RAID, which offers protection against bit rot and silent corruption, or does it ?. The problem is, I do not want RAID-Z because it does not support expansion, which means I have to purchase disks with larger capacity than all of my data if I want expansion.
So is it possible to use filesystem-level parity without RAID or unequal disk size RAID ? For example by allocation part of the disk space to store the parity of the "chunks" instead of storing the parity of equal sized disks on another disk as in RAID5.
Thanks everyone for answering.The following is the conclusion based on the answers:
No, it's not possible to use ZFS parity without RAID, but it's possible to use mirror copy without RAID.