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      When we tested mdadm and ext4, we didn’t really use the entire disk—we created a 1TiB partition at the head of each disk and used those 1TiB partitions. We also had to invoke arcane arguments—mkfs.ext4 -E lazy_itable_init=0,lazy_journal_init=0—to avoid ext4’s preallocation from contaminating our results.

      Using these relatively small partitions instead of the entire disks was a practical necessity, since ext4 needs to grovel over the entire created filesystem and disperse preallocated metadata blocks throughout. If we had used the full disks, the usable space on the eight-disk RAID6 topology would have been roughly 65TiB—and it would have taken several hours to format, with similar agonizing waits for every topology tested.

      So they tested a configuration that nobody’s going to be actually … running. I guess that’s part for the course with online performance testing magazines, but wow.

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        part for the course

        The expression is “par for the course”. It comes from golf.


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          Agreed. I’ll select & copy your message so that maybe iOS autocorrect can learn from it.

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      Any opinions on a good home setup for ZFS? (With ECC DRAM)

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        Depends what you already know / want out of it - I’ve had some success with FreeNAS, but it assumes quite a bit about what you would like.

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          I am mostly interested in protecting my data. Then there is cost. What are the options on the low end of cost?

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            ECC DRAM is a complex set of standards, and it’s very easy to burn money on incompatible motherboards, especially at the cheap end of the scale.

            Ex-server hardware tends to be dirt cheap for this kind of thing (especially right now). If you can figure out a way to run it without the noise driving you mad (maybe fitting watercooling?), that’s going to be the cheapest way to get a compatible ECC setup.

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            I’ve had good luck with HP microservers. I described it a while back, here: https://lobste.rs/s/j1qohm/silent_fanless_freebsd_desktop_server#c_rte6ka