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I assumed they are talking about the commonly spread myth that you need a gig of RAM for every terabyte of storage. I think that's recommended when doing dedupl
by boomboomsubban 3y ago
I assumed they are talking about the commonly spread myth that you need a gig of RAM for every terabyte of storage. I think that's recommended when doing deduplication, but for a simple NAS ZFS would use a comparable amount of memory as ext4 on RAID.
- tambourine_man 3y agoIs that really the case? Can you point to some references backing that up? (Hehe, unintentional pun)
- boomboomsubban 3y agoTrueNAS' general requirements are 8GB, and they spell out when you want more. Most of the situations you'd want more you'd also want more on RAID. https://www.truenas.com/docs/core/gettingstarted/corehardwareguide/ https://www.truenas.com/docs/core/gettingstarted/corehardwar...
- rincebrain 3y agoZFS will happily use a large amount of RAM for caching if you have it, but it'll run fine on a recent Pi (3 or 4, or not raspberry at all). It'll run fine but more sadly on older Pis running 32-bit kernels, since it does a looooooooot of 64-bit and wider operations, so you pay a nasty tax on that on 32-bit things. (Though the virtual address space limits might actually be sadder than the 64-bit operation penalty there, really...)
- waynesonfire 3y agoI'm running ZFS on the smallest AWS instance, running FreeBSD, and it does what i want it to do.
- tambourine_man 3y agoThat's surprising. I may try on my Pi. I have 40TB and am very happy with SnapRAID, but ZFS always seemed liked the “correct but expensive” solution.
- toast0 3y agoOh yeah. That was always a sketchy recomendation, but it sure did make its way around. I think deduplication is remarkably seductive, but doesn't seem worth the cost for almost anyone, given how it's implemented. IIRC, btrfs has a dedup option where you can link up duplicates later, and then you don't have to hold a dedupe table of everything all the time, and don't need to collect writes to check the dedupe table, etc. But rewriting data isn't how zfs rolls, and I get that.
- pseudalopex 3y agoOr the myth ZFS without ECC is more dangerous than anything else without ECC.
- fho 3y agoNot sure if a myth, iirc it was literally in the ZFS manual last time I looked into ZFS (which to be fair was 10+ years ago).
- boomboomsubban 3y agohttps://openzfs.org/wiki/System_Administration#Data_Integrity https://openzfs.org/wiki/System_Administration#Data_Integrit... >Misinformation has been circulated on the FreeNAS forums that ZFS data integrity features are somehow worse than those of other filesystems when ECC RAM is not used. That has been thoroughly debunked. All software needs ECC RAM for reliable operation and ZFS is no different from any other filesystem in that regard
- pseudalopex 3y agoThe documentation author refuted it 9 years ago.[1] Probably your understanding or memory was incorrect. [1] https://news.ycombinator.com/item?id=8438239 https://news.ycombinator.com/item?id=8438239