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  • [6.12.2] zfs write speed very slow (e.g. ~ 30MB/S)

    • Minor

    I'm trying to convert my btrfs drives to zfs  by

    * moving everything away from the btrfs drive

    * reformat to zfs 

    * and then move back to the newly formatted zfs


    However, zfs is extremely slow. Write speed around 30MB/s, sometimes even lower.


    Tried the unbalance plugin but also used rsync, also tried it with different values for --bwlimit, as found in in the forum for Prereleases. Not much change, see the attached plugin screenshot where the target disk4 is formatted with zfs.


    Not sure if I'm doing something wrong but with this speed, zfs is close to be unusable.




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    There's a known issue with zfs write speed on the array, but moving data from disk to disk with parity as you are doing will always be quite slow, even when using a different filesystem it won't be much faster, usually tops at around 60MB/s.

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    If it just would be 50-60MB/s ...  Will do a test later and move files to the remaining btrfs drive to cross-check 

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    2 minutes ago, hulk66 said:

    If it just would be 50-60MB/s .

    Yes, that should be about array to array write speed with btrfs/xfs, like mentioned with zfs write speed will be slower until that issue is fixed.


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    ok, thank you! Do you know if there any such thing as a ticket or so, which one could follow for his matter?

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