Low Data Transfer Speed within Shared Folders

1. offizieller Beitrag

    Hi Everyone, Merry Christmas!


    I'm quite new to OMV and this is my first post, please go easy on me!


    I'm having a transfer speed issue (at least I think it should be way faster)


    My setup is as follow:
    - Raspberry Pi 3b+
    - OMV 4
    - 3 HDD (1 x 500GB 2.5, 1 x 1TB 2.5, 1 x 2TB 3.5) connected to a 5V powered USB3.0 HUB which is connected to the PI
    - Formatted as EXT4
    - Combined to a Linear Raid (JBOD I believe is that called)
    - Sufficient power supply (5V for the PI and USB hub; 12V for 3.5 HDD)
    - Connected to router via network cable


    I use it mostly as a media server (plex) along with transmission


    Shared folders are:
    - AppData (currently empty)
    - Downloads (for transmission)
    - Media (for plex)


    The issue now is as follow:
    When I copy downloads (on my windows laptop, mapped network drive) from the "Downloads" folder to one of the sub-folders in "Media" the transfer speed fluctuates somewhere between 2.5 - 3.5 MB/sec.
    When I upload files from my computer to OMV its around 5-8MB/sec, download is about the same.


    I notice that the transfer speed goes up (ie to 3.5MB/sec) but then goes down to 2.5MB/sec, then it goes up again, down again and so on.


    This is a new setup. The previous setup (only 1 drive 500GB directly connected to the PI) copying within shared folders was super fast and download speed was quite stable at 12MB/sec.


    Appreciate any feedback!

    • Offizieller Beitrag

    Since you have downloads and media on separate shares, moving files between them means a round-trip of your network from the server to the laptop and back again.


    This is because as far as the laptop is concerned media and downloads are two separate filesystems. The laptop has no way of knowing that they both are parts of the same filesystem on the physical drives.


    If you instead had a single shared folder, perhaps "shared_files", then moving files would be instantaneous.


    You can then have downloads and media as top folders in shared_files.


    An alternative could be to login on the server using SSH and move the files local to the server. That would also be instantaneous. You could use Midnight Commander for instance.

    Moving files from one shared folder to another could be done on the comand line.
    Log in by using SSH and copy or move the files. Be sure to check if the file system permissions fit your needs after the action.


    Using this method the network is not involved at all, thus not limiting the transfer speeds.

    Thanks for the feedback!


    I can see the issue now. On my first setup, i had 1 shared folder and the other ones (downloads, media, etc) where sub-folders. so that would explain it, right?


    I'm highly unfamiliar with command line, since I have never worked on Linux enough to be patient enough. Also seems too complicated to me, considering that transmission is basically running around the clock, so I'm having constantly files to copy.


    I'll try to give midnight commander a try and see how I can manage that.


    For simplicity, would it make more sense to have one shared folder instead of what I have now?


    Also, comparing my download speeds from my first setup, it seems also slower right now (downloading files from media to my computer). Can this be because of the raid I made?


    Sorry for asking so much, but I'm trying to make this as simple as I possibly can but also as smart as possible (for example, more shared folders would be better to implement permissions for different users in the future i assume?)

    • Offizieller Beitrag

    If you are moving files within the same filesystem then it should be instantaneous. I assume that you copied files. Then the speed most likely was as good as you can expect.


    I belive you can have transmission automatically move a file to another folder when it has been downloaded.


    If you don't have a good reason why not, have only one shared folder. You might want more for separate logins for different purposes.


    As I understand it it is usually a bad idea to use RAID for personal use. Especially on RPI. Especially over USB. Especially over an USB hub. Especially if you are not comfortable with the command line and fully clear over what to do when the RAID fail, for some reason. Also I understand that if you want a fast NAS then RPI is the wrong SBC to use.

    Now I think I can give a better feedback. I probably forgot to consider transmission downloading files which also seems to slows down transfer speeds. For example yesterday, transmission was empty and suddenly my transfer speeds when up to 20MB/sec with mostly being around 12-14MB/sec, which I'm quite satisfied with actually.
    Download speed to my computer, I still need to do more tests, but that seems to be around 10MB/sec which is ok I guess, still trying to get to 12MB/sec though.


    So anyways, I think thats it for my issue.


    @Adoby, I'm aware that a raspberry pi NAS is super slow, and I never expected it to be fast. I just basically had the parts lying around which is a nice project for me to get into. Regarding the RAID, I don't know what I was thinking when I did that, because later I realized that I can just change folders for plex / transmission in case a drive is full. Anyways, I will probably make one main shared folder for plex and transmission and try to move everything there without messing up both plug ins. Should be not too hard I guess.


    Also, I had to use a USB hub, because as soon as I plugged in the second hard drive, both HDDs spun up and down and nothing was working, eventhough power supply was enough, so that was the best fix I could come up with to plug in 3 hard drives.


    Anyways, thanks everyone for helping out. Used midnight commander now and works quite well for me!


    Cheers Guys! (btw. do I have to close this thread or how does that work?)

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