ZFS won’t save you: fancy filesystem fanatics need to get a clue about bit rot
&gt; While it is true that keeping a hash of a chunk of data will tell you if that data is damaged or not, the filesystem CRCs are an unnecessary and redundant waste of space ...<p>A few years ago I, when I was on a game console team, a hardware engineer came to my desk and said, &quot;Can you find out what&#x27;s wrong with this disk drive?&quot; It had come from a customer whose complaint was that games sometimes failed to download and game saves became unreadable.<p>I spent a fun afternoon tracking down what turned out to be a stuck-at-zero bit on that drive&#x27;s cache. Just above the drive&#x27;s ECC-it-to-death block storage was this flaky bit of RAM that was going totally unchecked. The console had a Merkle-tree based file system and easily detected the failure, but without that addition checking the corruption would have been very subtle, most of the time.<p>Okay, so that&#x27;s just one system out of millions, right? What are the chances? Well, at the scale of millions, pretty much any hole in data integrity is going to be found out and affect real, live customers at <i>some</i> not insignificant rate. You really shouldn&#x27;t be amazed at the number of single-bit memory errors happening on consumer hardware (from consoles to PCs -- and I assume phones). You should expect these failures and determine in advance if they are important to you and your customers.<p>Just asserting &quot;CRCs are useless&quot; is putting a lot of trust on stuff that has real-world failure modes.