ZFS Metadata - How it works, plus discussion on corruption

[Arwen]

@SmallBarky

I don’t believe any had UPS systems

Again UPSes are not required for ZFS on-disk consistency;

ZFS pools & power loss - you won't lose data

One other problem that I thought of, storage device write cache. ZFS was originally written when HDDs had write caches that could re-order writes, (aka elevator seek). On power loss, (or OS crash), that could cause data loss. At one point, (around 2010), Sun Microsystems recommended disabling HDD write caches when using ZFS because of this problem. Eventually this problem was overcome by implementing and using write barriers. This meant that all the preliminary writes for a ZFS transaction, (a…

Of course, UPSes prevent corruption from poorly designed in hardware. Like hardware RAID controllers which uses elevator seek & writes.