Common Myths We Hear from the FreeNAS Community



  • FreeNAS seems to be shrouded in myths. Whether myths about RAID, ZFS, operating systems, or what have you, it seems that when you create a product and community focused around taking the "expert" out of a system, that you end up in a situation where myths easily take hold and no one takes the time to dispel them. FreeNAS has become a very dangerous product, mostly because of how it gets used, rather than issues with the product itself. Of course, FreeNAS suffers from the Jurassic Park Effect, improperly approaches front loaded engineering (by doing it backwards), not having an operational mindset, and they have had some pretty nasty failed released go to "production", and some real world data losses from their JPE problems; but these are not what I am concerned about there. Every vendor has their hiccups.

    Instead, my concerns here are around false information that comes from the community of FreeNAS users. In the real world, whenever I find someone running FreeNAS and ask why they are considering or have chosen FreeNAS, it is universally based on a myth or misunderstanding of the product or an underlying component of the product. For example, people often choose FreeNAS "because it has ZFS", which makes no sense unless it was the only product that had ZFS but many others do as well, so that would leave us asking why those weren't chosen based on the same logic. Or we find FreeNAS deployed in a less than ideal fashion and the odd deployment is based on a rumour or misconception such as believing that ZFS is dangerously fragile and doesn't work on hardware RAID.

    Here are some standard myths that FreeNAS users keep repeating:

    • ZFS is an alternative to RAID (it is really just standard software RAID)
    • ZFS RAID levels aren't standard (they are very standard)
    • ZFS is not subject to the risks of RAID (in fact, most of us use ZFS' RAID as the guide for calculating that risk in the first place!)
    • ZFS doesn't work on hardware RAID (works perfectly there)
    • That bit rot affects people every day and only ZFS can protect you (this isn't a real world fear for 99.99% of companies)
    • Software RAID is a miraculous thing and hardware RAID is useless (what the what?)
    • Caching is a unique feature (everyone has this)
    • Logical volumes are special (everyone has this)
    • Snapshots are special (everyone has this)
    • Scrubbing is special (everyone has this)
    • ZFS comes from FreeNAS and is unique to it (FreeNAS gets it from FreeBSD who gets it from Solaris. Also available on Linux esp. Ubuntu.)
    • You just use a GUI and don't need to know BSD (FreeNAS requires you to go to the command line and manage both FreeBSD and ZFS from the command line in a more complicated way than normal compared to just using FreeBSD or Ubuntu - so the need for command line skills, ZFS skills, and FreeBSD skills is actually greater with FreeNAS, rather than less.)


  • Since this was posted, some interesting new myths that we've heard:

    • ZFS doesn't use parity (like any RAID system it can but doesn't have to, but most people chose it for its parity features)
    • That ZFS has copies of the original data strewn about the disks rather than in expected locations.
    • That hardware RAID can't support compression of filesystems on top of it.

    In the years since the Cult of ZFS and Common ZFS Myths articles were posted, industry baseliners like CompTIA have added information to refute this misinformation not just into introductory level certifications, but also into the introductory certifications of the bench industry, like the A+. But even with this, we still see, although thankfully less often, these myths get brought out again. It shows how in areas like storage and security, where there tends to be a bit more fear and a little less broad knowledge, how easily we can convince even trained IT people that there might be "magic boxes" - the allure of technology being magic seems to be just too strong.



  • Way more discussion about this thread in this other thread: https://mangolassi.it/topic/19657/revisiting-zfs-and-freenas-in-2019