Hardware requirements for ZFS 2

  • Hi Guys,


    I currently have a 4x3Tb setup running in RAID6, but am starting to run out of space so I have just ordered another 2 3Tb drives.


    I want to switch to ZFS now that is a bit more mature.


    My question is ... will my hardware cope with it ?
    Current spec of NAS is:


    Asus H81I-Plus Motherboard
    Intel Celeron G1840 2.80GHz (Dual Core)
    Corsair XMS3 4GB (2x2GB) DDR3 PC3-12800C9
    IBM M1015 ServeRaid


    is it still the case that you need massive amounts of Ram to run ZFS (I read a very early document about it few years ago) my board can take up to 16Gb of Ram but is this really necessary ?
    And will the CPU be man enough to deal with ZFS ?


    What sort of specs are people using with ZFS ? I'd love some feedback / advice from you guys that have already gone down this route.


    Cheers


    Damob

  • The requirements depend on what u want to do with ZFS.


    In any case u need ECC RAM - everything else is like putting a dinosaur in a kindergarten - not a good idea.
    CPU is usually not a bottleneck.
    If u want encryption get a CPU with HW support.


    You will get good write speeds with 8GB of RAM. If you want snapshots more is good.
    If u want deduplication and or compression 16GB is probably needed for 12TB or maybe even more - dedup is a monster RAM eater from what I have read.

  • Thanks blublub,


    Can't do ECC RAM without swapping out my motherboard - so don't really want to do that, how much of a risk is it not using ECC ram ?


    I use my NAS for storing my documents, and as my media server (MediaBrowser) so most of what takes up space are mkv's so encryption,compression and deduplication is not that relevant.


    It's mostly the self healing aspect of ZFS that i'm interested in .. I want to avoid data rot as much as I can.

  • Thanks blublub,


    It's mostly the self healing aspect of ZFS that i'm interested in .. I want to avoid data rot as much as I can.


    If u want that feature you cannot go without ECC RAM. The "self healing" is based upon trusting the data in the RAM /calculated in the RAM. If the calculation is wrong then ZFS will not be aware of it.


    Example:
    data on disk is perfectly fine
    you read a file
    ZFS checks its integrety with checksums
    RAM is bad -> checksum in RAM will not match file on disk
    ZFS will correct the file on disk because it trusts the RAM calculation


    Your file is now corrupt - end of story. Worst case is whole FS will be f**** up.


    You have nothing of the ZFS security without ECC. I have been building PCs for over 15 years and yes RAM sometimes goes bad.

  • If u want deduplication and or compression 16GB is probably needed for 12TB or maybe even more - dedup is a monster RAM eater from what I have read.

    Compression is more dependent on CPU than RAM. Benchmarks has even proofed than enabling lz4 compression even improves write speed - compression can help reduced the need amount of data to be written.

  • Oh Cr4p !! that's sort of ruined that plan then X(
    Guess I'll stick with RAID 6 for the time being, and maybe look at replacing my Mobo / RAM later on.


    Cheers for the heads-up though guys, saved me from making a silly mistake !


    Ta


    Damob

  • The rule of thumb for ZFS is that you should use at least 4GB of RAM or a gig per TB of storage, whichever is greater - however this isn't always the case. There are plenty of good ZFS setups with 16GB of RAM with 96TB of storage. I would say you'd need to follow the RAM rule up to 16TB then you'll probably be fine for most home applications.


    As others have said, ECC memory is an absolute must. ZFS protects your data from corruption and relies on trusting that what it gets from RAM is not corrupted. By not using ECC you'll be in a situation where ZFS could unknowingly write corrupted data back to the disks because it trusts that the RAM is checking what it has given it.


    I'm running ZFS on a HP N54L and haven't had any CPU bottlenecks so far so you should be fine in that regard. :)

  • OK thanks all for your advice.


    I will look into replacing my board / RAM but have other bigger issues to deal with first .. new car .. old one is nearly dead !


    Thanks all
    Damob

  • As others have said, ECC memory is an absolute must.


    And even the holy ECC Ram can only correct 1-bit errors. 2-bit errors can be detected, but they can't be corrected. Not many can even detect 3-bit errors.


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    David

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