ram memory measurement for 8 GB or 16 GB ram

  • As I've been running FreeNAS with ZFS for number of years, I got a few things on that one.

    1. Max usage is 80% of the storage, otherwise, you will be hit with performance issues
    i.e. In your case 4x8TB = 24GB actual storage @ 80% = 19.2GB Abailable
    2. For resilvering/scrubbing/recovery you need 1GB of RAM per 1TB of data
    3. Dedup is best left turned off...need humongous amount of RAM for recovery
    4. Stick to 4 disks per POOL

    What I am currently trying to do is to use SnapRAID with OMV and see how that goes, and possibly migrate to it, as it promises data integrity of ZFS.

    I have no experience of BTRFS.....

  • You can get away with 16Gb if your ZFS pool is 16Gb. Also, ZFS recommendation is to have ECC memory. If you look into underlying technology under ZFS, it extensively use RAM before saving anything onto disks.

    I currently have FreeNAS, and I really need to restructure ZFS Pools, and it't not possible without new HDs. Idea of mine was to start making pools based on 4x4Tb drives, hence 16Gb RAM on N40L microserver would be adequate.

    If you already have 4x8Tb drives, I would recommend another 16Gb RAM as really necessary, as you will be running OS and many other processes.

    Quote from FreeNAS Requiremens

    1 GB per terabyte of storage is a standard starting point for calculating additional RAM needs, although actual needs vary. ECC RAM is strongly recommended.

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