FreeNAS people seem to mix up what&#x27;s recommended vs what&#x27;s required.<p>The whole myth that ZFS requires ECC memory comes from them, but in reality ECC is as much helpful with ZFS as with any other FS. It&#x27;s not that ZFS will start destroying your data if you don&#x27;t have ECC. It&#x27;s just that ZFS provides guarantees, but it can&#x27;t help much if data is corrupted in memory, but any other filesystem will also be affected in that scenario.<p>Similarly with 8GB. You can actually run ZFS on 1GB, but the more RAM you have the better. ZFS has ARC (Adaptive Replacement Cache[1]) which speeds up read access by storing in RAM most frequently accessed data.<p>Not running ARC won&#x27;t affect safety of your data, it&#x27;s just that you&#x27;ll get worse performance.<p>There are some warts ZFS (and most likely COW file systems) have. For example until ZFS will have a defragmenting tool (doesn&#x27;t looks like anyone is working on it) you don&#x27;t want ever to use more than 80% of your disk. If you do, you&#x27;ll permanently reduce performance of the pool and currently the only fix would be to backup all the data, wipe disk and restore it (this effectively will defragment it).<p>Another issue is that deduplication in ZFS is essentially useless. It requires obscene amount of RAM to be used, and if you enable it with less, it&#x27;ll drastically reduce performance as well. Instead of deduplication it&#x27;s better to just enable compression.<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Adaptive_replacement_cache" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Adaptive_replacement_cache</a>