memory – Using Non-ECC Memory with ZFS: Is It a Bad Idea?

eccmemorytruenaszfs

I have a new server and am planning to upgrade the paltry 2 GB of memory to the maximum of 16 GB. (Theoretically 8 GB is the limit, but empirically 16 GB has been shown to work.) Some guides advise that ECC memory is not that important, but I'm not so sure I believe this.

I've installed FreeNAS and am planning to add ZFS volumes as soon as my new hard drives arrive. Would it be stupid to skimp and get non-ECC memory for a ZFS-based NAS? If it's necessary, then I'll bite the bullet, but if it's just paranoia, then I'll probably skip it.

Is there any reason ZFS or FeeeNAS specifically would require ECC memory, or suffer especially when running on a system using non-ECC memory?

Best Answer

I would argue that running FreeNAS with non-ECC RAM is a stupid idea, as is running it as a virtualized guest, when the data stored on the ZFS volume is important.

Joshua Paetzel, one of the FreeNAS developers, has a good write-up on this topic: http://www.freenas.org/whats-new/2015/02/a-complete-guide-to-freenas-hardware-design-part-i-purpose-and-best-practices.html.

TL;DR

ZFS does something no other filesystem you’ll have available to you does: it checksums your data, and it checksums the metadata used by ZFS, and it checksums the checksums. If your data is corrupted in memory before it is written, ZFS will happily write (and checksum) the corrupted data. Additionally, ZFS has no pre-mount consistency checker or tool that can repair filesystem damage. [...] If a non-ECC memory module goes haywire, it can cause irreparable damage to your ZFS pool that can cause complete loss of the storage.

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