Harddrive very slow while writing, very fast while reading?

  • Hi there,

    I have an OMV running on a Raspberry Pi 4, it's hooked up with two USB3 harddrives, both LaCie d2 Quadra, one 4TB and the other 6TB.

    On the 6TB, it's very slow to copy data onto it. I'm using my Win 10 PC and get a speed of around 2-3 MB/s. When I copy from it to my PC, it's pretty fast (around 80-100 MB/s).
    At first I thought that's some sorta limitation of OMV, but the the 4TB disk doesn't show this behaviour. It's as fast while writing as it is when reading.

    I formatted both disks with OMV, both run on EXT4. While setting up OMV, I didn't do anything differently with each of the disks; in their former usecase there were no signs of slowdowns when reading or writing.
    I'm a real noob regarding Linux so I'm a bit lost on what could cause this, and what I could do about it (as well as which kinda info you guys need, haha)


  • There are huge differences between different USB/SATA interfaces. Some work fine with windows but are very bad with Linux.

    Things like cables or USB hubs sometimes can also have a big influence.

    The fact that one HDD is OK, but the other isn't, seem to indicate that something is wrong with the slow HDD, the USB/SATA interface or the cable. And OMV or the RPi is not to blame.

    Be smart - be lazy. Clone your rootfs.
    OMV 5: 9 x Odroid HC2 + 1 x Odroid HC1 + 1 x Raspberry Pi 4

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